PREFACEThe idea for this book was born during a workshop A format was chosen that starts with what the sur-on anaesthesia for laparoscopic surgery, which I geon is actually doing to the patient, proceedsorganized several years ago. What was intended for a through an in-depth look at the patient’s cardiopul-regional audience of perhaps 250 anaesthetists at monary responses to the surgeon’s manipulations,most, turned into an international event with the par- and then distils hands-on practical recommendationsticipants spilling out of the main lecture hall to view and guidelines for anaesthetic management from thisthe presentations on video screens in adjacent halls. basic information. These include tips on anaestheticThe overwhelming resonance of the workshop and regimens derived from the application of recent phar-the numerous requests for accompanying material macokinetic and pharmacological research results towas ample evidence of the need for a comprehensive the clinical demands of minimally invasive opera-treatise of the subject that merged experimental study tions. Special attention is given to the typical patientdata with clinical reality and the requirements of peri- proﬁle for selected operations; what to look for duringoperative patient care. their preoperative work-up, and what to watch for during and after surgery. With this synoptic founda-This book is designed to ﬁll the gap. It was clear that tion, the reader also has a better grasp of what goesalthough laparoscopic procedures were the original awry during typical adverse events and complications,focus of attention and should be given the most space, and how these can be prevented and treated.the scope of the book would have to be widenedto include other minimally invasive surgical proce- The reader can easily choose just what depth of infor-dures, such as thoracic surgery, laser surgery of the mation is required for the task at hand, be it a how-to-upper airways or neurosurgery, that require adjust- do anaesthetic recipe or a fully-referenced detailedments and adaptations of routine anaesthetic man- presentation. Important points are summarized inagement, or entail speciﬁc risks requiring speciﬁc highlighted charts that allow the reader to ﬁnd perti-precautions. These specialties are presented in sepa- nent information at a glance, and numerous illustra-rate chapters. tions are included to enhance clarity.
FOREWORDMinimally invasive surgery is increasingly popular book of this kind. In the early days of minimally invasivewith management in the drive to reduce hospital surgery some terrible disasters – unnoticed perfo-expenditure and especially the expense of patients’ rated bowel, massive haemorrhage from damaged ves-stay overnight in hospital after surgical procedures. sels, gas embolism, etc. – befell some patients. MostMoreover, our patients can beneﬁt enormously through often this was due to poor surgery by inexperiencedreduced disturbance of their well-being and less surgeons; this hastened the need for absolutely con-interference with metabolic and other physiological tinuous and complete monitoring of the patient byprocesses. It has been made possible by amazing devel- the anaesthetist on a beat-by-beat and breath-by-opments in surgical techniques such that conventional breath basis, surely the tenet of any form of ﬁrst-classsurgery for many procedures as we used to know them modern anaesthetic care. Fortunately, much of this sur-hardly exists today. Historically, advances in surgery veillance can easily be carried out with modern patientwere made possible through advances in anaesthesia; monitoring equipment but it must be backed up by thehowever, to some extent, at least, the boot is on the attention of the attending anaesthetist and interpreta-other foot because these advances in surgery through tion using all his vital senses.minimally invasive (so-called keyhole) techniques have Minimally invasive surgery continues to expand. How-demanded the reﬁnement and development of exist- ever, now is a good time to consolidate and reviewing anaesthetic techniques and the introduction of anaesthetists’ requirements in this area and Tomnew drugs. Notably, these methods require keeping Crozier has included consideration of bariatric surgery,the patient safe at all times and returning the patient laser surgery, thoracic surgery and neurosurgery sinceto full consciousness extremely rapidly, yet with free- these areas nowadays are tending to become minimallydom from pain, immediately the surgical procedure is invasive. He has performed his task extremely well.completed.Prof. Tom Crozier, with long-standing experience of Anthony P Adamsthis subject, writes from Göttingen – arguably the Emeritus Professor of Anaesthetics in the University offoremost centre of excellence of anaesthesia in Europe. London at Guy’s, King’s & St Thomas’ Hospitals’Readers will note that, ﬁrst and foremost, this is an School of Medicine; lately Editor-in-Chief,essentially practical book. He deﬁnes the subject in European Journal of Anaesthesiology.terms of practicalities such that some often overlookedaspects, for example surgery of the upper aerodiges- London, UKtive tract, are included. This is eminently sensible in a July 2004.
ACKNOWLEDGEMENTSThis book was made possible by the support and input I am particularly indebted to Prof. Wolfgang Steiner,of many friends and colleagues from many specialties, chairman of our university’s Department ofwhose contributed time and resources greatly enriched Otorhinolaryngology, for his critical comments on thethe results. Without the initial enthusiasm, innovative ﬁrst draft of the chapter on laser surgery, and for theactivities and cooperation of members of the depart- contribution of numerous illustrations for this chap-ment of general surgery, particularly Dr Thomas ter from his vast photographic archives.Neufang, Dr Gerd Lepsien and Dr Olaf Horstmann, I must extend my thanks to Prof. Michael Buchfelder,for the evolving techniques of laparoscopic surgery, my chairman of the Department of Neurosurgery andexperience in the anaesthetic management of these authority on endoscopic pituitary surgery, and hisoperations would have been very limited, and several of associate Dr Hans Ludwig, specialist for endoscopicour research projects would not have been possible. I neurosurgery, for their useful input on the topic ofmust thank Dr Arnd Timmermann of the Department minimally invasive neurosurgery.of Anaesthesiology, Emergency and Intensive CareMedicine, Dr Ralph Rödel of the Department of My colleagues in the Department of AnaesthesiologyOtorhinolaryngology and Dr Hilmar Dörge of the deserve particularly heartfelt mention for their inter-Department of Cardiothoracic Surgery for contribut- est in this project and their unspoken, amused toler-ing valuable photographic material. ance of my preoccupation.Prof. Dietrich Kettler, chairman of our Department But above all, I am deeply grateful for the support,of Anaesthesiology, Emergency and Intensive Care enthusiasm and patience of my wife, Chris, and our chil-Medicine, deserves honourable mention for providing dren, Jesse, Tristan, Julian and Hanna, who had to putresearch facilities and a creative environment in which up with a permanently distracted, frequently distraught,this project could come to fruition. and repeatedly despairing family member during the ﬁnal months running up to the manuscript deadline.Prof. Ulrich Braun, section head of our department Without them, this book would not have happened.and current president of the European AirwayManagement Society, provided me with a number ofimportant tips on airway management in the course of Göttingen,many discussions. July 22, 2004
INTRODUCTION 1The term minimally invasive surgery conjures up an Most, but not all, of these procedures are performedimage of innovation and cutting-edge technology that through small incisions with the aid of an endoscope.differs in a fundamental way from conventional surgi- This has led some, particularly in the UK, to prefercal methods. Novel procedures have been introduced the term “minimal access surgery”. The endoscopethat have a spectrum of complications and contra- most frequently used is the laparoscope, and the pro-indications that differs distinctly from that of the cedures are sometimes referred to collectively asconventional method and requires a modiﬁcation of laparoscopic surgery, even though the operation sitestandard anaesthetic management. These, obviously, might be in the retroperitoneum or the mediastinum.deserve to be dealt with in detail in a book on peri- Since these are the operations that started the presentoperative management from the more comprehensive fascination with minimal invasiveness, and are alsoviewpoint of the anaesthetist. But all attempts at a the ones whose anaesthetic management differ mostgeneral deﬁnition of which procedures should be from conventional operations, they shall be dealt withincluded show how elusive the term actually is. If one ﬁrst in this introductory chapter.takes it to describe procedures that do not require Laparoscopy itself is not a new technique, but one thatlarge incisions or extensive tissue destruction, it would has been in use since the beginning of the 20th century,include such diverse operations as circumcisions, although it was mainly used only for diagnosticcataract extractions or transurethral bladder surgery – purposes. The urologist Georg Kelling examined thenone of which belong in this book. What then is the peritoneal cavity of a dog in 1901 with the aid ofcharacteristic, the common denominator of what we a cystoscope, and called the procedure “koelioskopie”,generally refer to as “minimally invasive”? The the term by which it is still known in France.1 In 1910,answer lies in the context: minimally invasive does not Jacobaeus described the ﬁrst major series of such exam-refer to the magnitude of invasiveness as an absolute inations in humans, in whom he studied both the peri-measure, but rather to the invasiveness compared toneal and the thoracic cavities.2 He coined the termswith that of the conventional procedure. Add to this “Laparoskopie” and “Thorakoskopie” to describe thethe element of novelty and a particular relevance for two techniques. Kalk improved the optical instrumentsanaesthesia and one has a fairly good description of and used two trocars instead of only one.3 In 1938,the scope of this book. Janos Veress introduced the insufﬂation needle that stillMinimally invasive surgery has virtually revolution- bears his name (Figure 1.1).4 The introduction of auto-ized the surgical therapy of a large variety of diseases matic insufﬂation devices resulted from the innovativein the space of just a few years. While progress in themore spectacular surgical specialties, such as heartsurgery, organ transplantation, or separating Siamesetwins, captures the public imagination to a greaterdegree, these beneﬁt only a small segment of the popu-lation. Endoscopic surgery, on the other hand, haschanged the management of some of the most fre-quently performed surgical procedures, the mostnotable among these being gall bladder surgery. Thecontinuing interest in endoscopic surgery is not onlydue to its aesthetic and cosmetic advantages, but alsoto the potentially smoother postoperative course, with Figure 1.1 Details of the Veress needle. The round tip offewer complications and a swifter return of the the spring-loaded obturator is pushed back into the needlepatient to his normal daily life. However, in order to shaft while the needle tip is penetrating the abdominal wall.exploit this potential to its fullest, perioperative It springs forward as soon as the needle tip has cleared theanaesthetic management must adapt to the altered peritoneum and protects against damage to the intestine orrequirements of the new techniques. other viscera.
2 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYwork of Karl Semm in the 1960s. Surgical working operations have become part of the repertoire ofconditions were improved greatly by attaching a video nearly every moderately well-equipped clinic. Therecamera to the endoscope and transmitting the view to a is then the shifting group of laparoscopic operationstelevision monitor. This allowed the surgeon to stand in that are routinely performed in specialized centres,a normal position, and also made it possible to train and although no longer regarded as investigational,several assistants simultaneously. nevertheless require the experience of specialists. AndGynaecologists, above all Semm and Lindemann, then there is a continuously growing list of laparo-were the ones who pioneered the development of a scopic procedures that stand more or less at the cut-technique with which intra-abdominal operations ting edge of medical science – some of which ﬁndcould be carried out without having to make a large their way into clinical routine, while others areabdominal incision.5 This led to a marked increase in dropped as not practicable. Laparoscopic operationsthe number of laparoscopic operations in the 1970s, routinely offered by many hospitals include cholecys-when laparoscopic ligation of the Fallopian tubes tectomy, appendectomy,9,10 tubal ligation, treatmentbecame a popular method of contraception. of ectopic pregnancies, minor urological operations and many others.11,12 Other operations such as herniaThe ﬁrst laparoscopic cholecystectomy, which might be repair, laparoscopically-assisted vaginal hysterec-regarded as the birth of minimally invasive surgery as tomy,13–15 enucleation of myomas, ovarial cysts,we understand it, was performed by Philippe Mouret etc.16–20 have also become standard.in Lyons in March 1987. From this moment on, thetechnique spread worldwide, despite the controversy it Some hospitals perform extensive abdominal andignited and the vigorous initial resistance from parts of thoracic operations endoscopically, including majorthe surgical establishment.6–8 In time, other surgical bowel resections, pancreatectomy, splenectomy andspecialties, such as urology, gynaecology and thoracic even oesophagectomy.21–26 A wide range of urologicalsurgery, developed their own applications for the endo- operations such as nephrectomy.27–29 adrenalectomy24scopic technique and the cholecystectomy was joined or radical prostatectomy with retroperitoneal lym-by numerous other indications and operations. phadenectomy30 are performed endoscopically. Paedi- atric urology is another ﬁeld in which endoscopicOne salient feature of the boom in laparoscopic surgery operations are becoming very common.31 Opinionswas the dramatic increase in the average duration ofthe operations due to the shift in the spectrum of sur-gical procedures. While the usual maximum duration Table 1.1 Selected endoscopic operationsof the typical diagnostic or sterilization procedure wasless than 20 min, the average duration of laparoscopic Operation Where conductedoperations is now 60–120 min, with some even lastingmany hours. A second feature of the rapid expansion Cholecystectomy General hospitalswas that the indications widened to encompass a com- Hernia repairpletely different patient population; whereas laparo- Appendectomy Tubal ligationscopic surgery had been formerly performed mainly Uterine myomason healthy young women, all age groups were now rep- Cryptorchism, orchidopexyresented, from the hypotrophic, premature neonate to Ectopic pregnancythe nonagenarian. The method was also no longer Oophorectomy etc.restricted to large medical centres, but had spread withincredible speed on a broad front with even small- and Colorectal surgery Specialized centres Gastric surgerymedium-sized hospitals taking advantage of the new Splenectomytechniques. These factors meant that every anaes- Bariatric surgerythetist was likely to be required to deal with laparo- Lung surgeryscopic operations of varying difﬁculty at some point. Coronary artery surgery Thoracic sympathectomy OesophagectomyLaparoscopic operations Nephrectomy, kidney donor nephrectomyIn the short time since the ﬁrst laparoscopic cholecys- Adrenalectomytectomy was performed, development has advanced at Radical prostatectomysuch a rapid pace that there is now almost no surgical Hepatic resection Retroperitoneal and pelvicprocedure that has not at least been attempted with lymphadenectomy etc.endoscopic methods. Certain standard laparoscopic
INTRODUCTION 3are divided regarding the question of whether laparo- peritoneum, the obturator tip springs forward, pre-scopic surgery of malignant tumours is contraindi- venting the needle from damaging the intestines orcated,30,32,33 while another controversy involves the other intra-abdominal organs. Once the correctquestion of whether laparoscopic surgery is con- intraperitoneal position of the Veress needle has beentraindicated during pregnancy.34–36 Obesity was once conﬁrmed, insufﬂation is started slowly and theconsidered almost an absolute contraindication patient is monitored closely. The gas ﬂow rate is thenagainst laparoscopic surgery, but has now morphed increased and the abdomen inﬂated to a pressure ofinto a strong indication.37,38 Even weight reduction about 12 to 15 mmHg. IAP is kept constant with ansurgery in the morbidly obese is thought to have a electronically controlled insufﬂator (Figure 1.3) at alower total risk of serious complications when per- level sufﬁcient to maintain optimal operating condi-formed laparoscopically. Table 1.1 presents an tions for the surgeon (usually about 10–15 mmHg).overview of the range of endoscopically performed Neuromuscular block must be sufﬁcient during thisoperations. This list is neither comprehensive nor period to keep the abdominal cavity compliant, and toﬁnal, as new techniques are constantly being added, prevent its being compressed by the return of muscu-and interventions regarded as investigational at best lar tension.today, will have become routine operations tomorrow. The typical adverse events that can happen duringThe use of new techniques, such as the abdominal this phase of the operation is the insufﬂation of gaswall lift39,40 or balloon dilators,41 will help to avoid the into preperitoneal tissue or directly into a blood ves-problems associated with gas insufﬂation and sel. The former is not infrequent, but is rarely ser-increases of intra-abdominal pressure (IAP).42 ious, and requires no particular action on the part of the anaesthetist. Intravascular gas insufﬂation, on the other hand, can be extremely serious and requiresTechnical aspects of rapid, deliberate action to avoid a lethal outcome (seelaparoscopic surgery Chapters 2 and 6).Laparoscopic operations are basically very stand- When the abdomen has been sufﬁciently inﬂated, theardized procedures that begin and end with a set Veress needle is removed and replaced with a largersequence of events. A brief description of these phases trocar introduced through the same incision (Figurewill help to understand the contribution required of 1.4). The primary complication of this manoeuvre isthe anaesthetist and also to understand the pathology injury to large vessels, such as the aorta or the iliacof a number of potentially lethal complications that vessels,44,45 or perforation of hollow viscera. Safetycan occur during laparoscopic surgery, most of which trocars with a sharp tip that retracts itself automati-are caused by faulty surgical technique or malfunc- cally once it has passed the peritoneum are now avail-tioning equipment. These points will be taken up in able. The obturator in the trocar is then removed andmore detail in the following chapters. a laparoscope is introduced through the sleeve and used to guide the placing of the following trocars, theIn the ﬁrst step of the operation, the abdomen is number and location of which vary according to theinﬂating by leading gas into the abdominal cavity operation. The ﬁrst trocar is used for intraoperativeunder pressure to create a pneumoperitoneum. Thisis sometimes referred to as a capnoperitoneum43 inorder to call attention to the particular problems thatarise from using carbon dioxide (CO2) as the insufﬂa-tion gas (see Chapter 2). The surgeon lifts the ventralwall of the abdomen and introduces a speciallydesigned safety needle through a small incision in thenavel (Figure 1.2) for the initial inﬂation phase. Theabdominal muscles must be well relaxed for thismanoeuvre to succeed. This needle, known as a Veressneedle after its inventor, is about 3–4 mm in diameter,and has a blunt, spring-loaded obturator that pro-trudes past the tip of the needle (see Figure 1.1). Whenthe needle meets ﬁrm resistance, as for examplewhen it is pushed through fascia or muscle, the tipof the obturator is pressed back, exposing the sharptip of the needle. After the needle penetrates the Figure 1.2 Blind introduction of the Veress needle.
4 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY procedure, there was a mortality rate of 0.09% of a total of 265,900 laparoscopies performed. From 1983 to 1985, the rate had fallen to 0.024% of almost 250,000 operations.46,47 In the US in the year 1977– 1978, a mortality rate of 0.04% was registered for 750,000 sterilizations, which were carried out by laparoscopy as well as laparotomy. Of the cases result- ing in death, 16 occurred in connection with laparoscopy, of which six were classiﬁed as anaesthetic complications. Even for the very short surgical proce- dures evaluated in this study, the risk of death was low but not negligible, considering that the patients were healthy and young. The expanding range of indications with operations having an order of magnitude increase in duration, and the inclusion of patients from extreme age groups and high-risk patients with serious pre- existing pathologies will obviously increase the risk of morbidity and mortality. The realization of this fact should act as a clear warning against incautiously equating minimal invasiveness of the operation with minimal risk to the patient, and should induce the anaesthetist to do his or her utmost to contribute towards minimizing this risk. The most important fac- tors that the anaesthetist has to take into account dur- ing laparoscopic operations are the pathophysiological changes due to gas insufﬂation, the risk of intravascular gas injection and the occasionally extreme position of the patient.Figure 1.3 The basic mobile unit for laparoscopic surgery.The unit contains the insufﬂator for creating and maintain- There are other entire groups of minimally invasiveing a constant pressure in the body cavity, a bottle of pres- operations that are not performed by laparoscopy andsurized CO2, a peristaltic pump to irrigate and rinse the thus are not associated with the problems of the pneu-surgical ﬁeld, a cold-light unit for illumination of the surgi- moperitoneum and CO2 insufﬂation. They will becal ﬁeld, a diathermy unit for coagulation and cutting, a described in detail in their respective chapters and arevideo monitor for observing the operation and a video therefore only mentioned shortly at this point. Amongrecorder for documentation. these are thoracoscopic surgery, minimal access car- diac and coronary surgery, endoscopic laser surgery of the aerodigestive tract and endoscopic neurosurgery. Thoracoscopic operations differ less from their con- ventional counterparts than the laparoscopic opera- tions do from theirs, and anaesthetic management will not require the same extent of adaptive modiﬁcations. The peripheral lung is easily accessible with an endo- scope, and thoracoscopic operations, such as wedge resection or lobectomy, ablation of blebs and othersFigure 1.4 Trocar with sharp obturator. have become common.48–50 The mediastinum can be approached either by the traditional suprasternal access or through the pleural cavity after allowing theinsufﬂation and it can become dislodged with result- lung to collapse.51,52 Cardiac and coronary artery sur-ing insufﬂation of gas into preperitoneal tissues. The gery can be considered minimally invasive if theyanaesthetist is frequently the ﬁrst to notice this prob- avoid using a midline sternotomy or extracorporeallem when end-tidal CO2 concentrations start to rise. circulation, the two factors that contribute most to theStatistics on the mortality associated with laparoscopy invasiveness of the conventional methods.53are available from 1949 to the present. In the period Endoscopic laser surgery of the aerodigestive tractfrom 1949 to 1977, when it was primarily a diagnostic allows operations that are not possible by any other
INTRODUCTION 5means.54 Tissue trauma can be extensive when consid- 14. Semm K. Hysterektomie per laparotomiam oder perered in relation to the narrow anatomy of the larynx, pelviskopiam. Ein neuer Weg ohne Kolpotomie durchbut postoperative recovery is rapid and usually CASH [Hysterectomy via laparotomy or pelviscopy. A new CASH method without colpotomy]. Geburtshilfeuneventful. Endoscopic and microsurgical procedures Frauenheilkd 1991; 51: 996–1003.in neurosurgery are truly much less invasive than their 15. Daniell JF, Kurtz BR, McTavish G et al. Laparo-conventional counterparts and do not generally scopically assisted vaginal hysterectomy. The initialrequire any modiﬁcation of anaesthetic management. Nashville, Tennessee, experience. J Reprod Med 1993; 38: 537–542.The following chapters will deal with important 16. Chatwani A, Yazigi R, Amin-Hanjani S. Operativeanaesthesiological aspects of modern minimally inva- laparoscopy in the management of tubal ectopic preg-sive surgery, be it endoscopic surgery of the abdomen nancy. J Laparoendosc Surg 1992; 2: 319–324.or thorax, endoscopic laser surgery of the larynx and 17. Lehmann-Willenbrock E, Mecke H, Semm K.adjacent structures, or endoscopic neurosurgery. Pelviskopische Ovarialchirurgie–eine retrospektiveThey are designed to offer the anaesthetist the spe- Untersuchung von 1016 operierten Zysten. Geburtshilfecialized theoretical and practical knowledge which he Frauenheilkd 1991; 51: 280–287.or she needs to meet the particular challenges of these 18. Mettler L, Caesar G, Neunzling S, Semm K.operations, and to provide competent anaesthetic care Stellenwert der endoskopischen Ovar-Chirurgie –with optimal risk reduction for the patient. kritische Analyse von 626 pelviskopisch operierten Ovarialzysten an der Universitats-Frauenklinik Kiel 1990–1991 [Value of endoscopic ovarian surgery – criti- cal analysis of 626 pelviscopically operated ovarian cystsReferences at the Kiel University Gynecologic Clinic 1990–1991]. Geburtshilfe Frauenheilkd 1993; 53: 253–257. 1. Kelling G. Über Oesophagoskopie, Gastroskopie und 19. Neeser E, Hirsch HA. Diagnostische und therapeutis- Koelioskopie. Munchen Med Wochenschr 1901; 49: 21–31. che Eingriffe bei Extrauteringraviditat [Diagnostic and 2. Jacobaeus HC. Über die Möglichkeit die Zystoskopie therapeutic interventions in extrauterine pregnancy]. bei Untersuchung seröser Höhlungen anzuwenden. Geburtshilfe Frauenheilkd 1987; 47: 149–153. München Med Wochenschr 1910; 57: 2090–2098. 20. Nezhat F, Winer W, Nezhat C. Salpingectomy via 3. Kalk H. Erfahrungen mit der Laparoskopie. Z klin laparoscopy: a new surgical approach. J Laparoendosc Med 1929; 111: 303–319. Surg 1991; 1: 91–95. 4. Veress J. Neues Instrument zur Ausführung von 21. Law WL, Chu KW, Tung PH. Laparoscopic colorectal Brust-oder Bauchpunktionen und Pneumothoraxbe- resection: a safe option for elderly patients. J Am Coll handlung. Dtsch Med Wochenschr 1938; 41: 1480–1483. Surg 2002; 195: 768–773. 5. Semm K. Pelviskopie und Hysteroskopie. Stuttgart: 22. Cuschieri SA, Jakimowicz JJ. Laparoscopic pancreatic Schattauer Verlag, 1976. resections. Semin Laparosc Surg 1998; 5: 168–179. 6. Keith RG. Laparoscopic cholecystectomy: let us con- 23. Rescorla FJ, Engum SA, West KW, Tres Scherer III trol the virus. Can J Surg 1990; 33: 435–436. LR, Rouse TM, Grosfeld JL. Laparoscopic splenec- 7. Miller TA. Laparoscopic cholecystectomy: passing tomy has become the gold standard in children. Am fancy or legitimate treatment option? Gastroenterology Surg 2002; 68: 297–301. 1990; 99: 1527–1529. 24. Heslin MJ, Winzeler AH, Weingarten JO, Diethelm 8. Tompkins RK. Laparoscopic cholecystectomy. Threat AG, Urist MM, Bland KI. Laparoscopic adrenalec- or opportunity? Arch Surg 1990; 125: 1245. tomy and splenectomy are safe and reduce hospital stay 9. Nowzaradan Y, Westmoreland J, McCarver CT, and charges. Am Surg 2003; 69: 377–381. Harris RJ. Laparoscopic appendectomy for acute appen- 25. Collard JM, Lengele B, Otte JB, Kestens PJ. En bloc dicitis: indications and current use. J Laparoendosc and standard esophagectomies by thoracoscopy. Ann Surg 1991; 1: 247–257. Thorac Surg 1993; 56: 675–679.10. Pier A, Gotz F, Bacher C. Laparoscopic appendectomy 26. Gossot D, Fourquier P, Celerier M. Thoracoscopic in 625 cases: from innovation to routine. Surg Laparosc esophagectomy: technique and initial results. Ann Endosc 1991; 1: 8–13. Thorac Surg 1993; 56: 667–670.11. Fahlenkamp D, Raatz D, Schonberger B. 27. Hensman C, Lionel G, Hewett P, Rao MM. Laparoskopische Diagnose und Therapie des Laparoscopic live donor nephrectomy: the preliminary Kryptorchismus. Urologe A 1992; 31: 328–332. experience. Aust NZ J Surg 1999; 69: 365–368.12. Jarow JP, Assimos DG, Pittaway DE. Effectiveness of 28. Clayman RV, Kavoussi LR, Figenshau RS, Chandhoke laparoscopic varicocelectomy. Urology 1993; 42: 544–547. PS, Albala DM. Laparoscopic nephroureterectomy:13. Gill F, Wierrani F, Grunberger W. Die pelviskopische initial clinical case report. J Laparoendosc Surg 1991; Hysterektomie – eine prospektive Vergleichsstudie über 1: 343–349. 40 Fälle [Pelviscopic hysterectomy – a prospective com- 29. Kavoussi LR, Kerbl K, Capelouto CC, McDougall parative study of 40 cases]. Geburtshilfe Frauenheilkd EM, Clayman RV. Laparoscopic nephrectomy for renal 1992; 52: 681–683. neoplasms. Urology 1993; 42: 603–609.
6 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY30. Rassweiler J, Tsivian A, Kumar AV et al. Oncological laparoscopic cholecystectomy. Acta Anaesthesiol Scand safety of laparoscopic surgery for urological malig- 2003; 47: 838–846. nancy: experience with more than 1000 operations. 43. Blobner M, Felber AR, Hosl P, Gogler S, Schneck HJ, J Urol 2003; 169: 2072–2075. Jelen Esselborn S. Auswirkungen des Kapnoperi-31. Peters CA. Laparoscopy in pediatric urology. Curr toneums auf den postoperativen Kohlendioxidhaushalt. Opin Urol 2004; 14: 67–73. Anaesthesist 1994; 43: 718–722.32. Ordemann J, Jacobi CA, Schwenk W, Stosslein R, 44. Bacourt F, Mercier F. Plaies de l’aorte abdominale au Muller JM. Cellular and humoral inﬂammatory cours des laparoscopies [Injuries to the abdominal aorta response after laparoscopic and conventional colorectal during laparoscopy]. Chirurgie 1993; 119: 457–461. resections. Surg Endosc 2001; 15: 600–608. 45. Apelgren KN, Scheeres DE. Aortic injury. A cata-33. Wexner SD, Cohen SM. Port site metastases after strophic complication of laparoscopic cholecystectomy. laparoscopic colorectal surgery for cure of malignancy. Surg Endosc 1994; 8: 689–691. Br J Surg 1995; 82: 295–298. 46. Riedel HH, Lehmann Willenbrock E, Conrad P,34. Reedy MB, Kallen B, Kuehl TJ. Laparoscopy during Semm K. German pelviscopic statistics for the years pregnancy: a study of ﬁve fetal outcome parameters 1978–1982. Endoscopy 1986; 18: 219–222. with use of the Swedish Health Registry. Am J Obstet 47. Riedel HH, Lehmann Willenbrock E, Mecke H, Gynecol 1997; 177: 673–679. Semm K. The frequency distribution of various35. Al-Fozan H, Tulandi T. Safety and risks of laparoscopy pelviscopic (laparoscopic) operations, including com- in pregnancy. Curr Opin Obstet Gynecol 2002; 14: plications rates – statistics of the Federal Republic of 375–379. Germany in the years 1983–1985. Zentralbl Gynakol36. Oelsner G, Stockheim D, Soriano D et al. Pregnancy 1989; 111: 78–91. outcome after laparoscopy or laparotomy in pregnancy. 48. Kirby TJ, Rice TW. Thoracoscopic lobectomy. Ann J Am Assoc Gynecol Laparosc 2003; 10: 200–204. Thorac Surg 1993; 56: 784–786.37. Gadacz TR, Talamini MA. Traditional versus laparo- 49. Inderbitzi R, Furrer M, Klaiber C, Ris HB, Striffeler scopic cholecystectomy. Am J Surg 1991; 161: 336–338. H, Althaus U. Thoracoscopic wedge resection. Surg38. Miles RH, Carballo RE, Prinz RA et al. Laparoscopy: Endosc 1992; 6: 189–192. the preferred method of cholecystectomy in the 50. Hazelrigg SR, Landreneau RJ, Mack M et al. morbidly obese. Surgery 1992; 112: 818–822. Thoracoscopic stapled resection for spontaneous pneu-39. Paolucci V, Gutt CN, Schaeff B, Encke A. Gasless mothorax. J Thorac Cardiovasc Surg 1993; 105: 389–392. laparoscopy in abdominal surgery. Surg Endosc 1995; 51. Fiocco M, Krasna MJ. Thoracoscopic lymph node dis- 9: 497–500. section in the staging of esophageal carcinoma.40. Volz J, Volz E, Koster S, Weiss M, Wischnik A, J Laparoendosc Surg 1992; 2: 111–115. Melchert F. Pelviskopisches Operieren ohne 52. Facciolo F, Sposi A, Catarci M, Della-Rocca G, Pneumoperitoneum? Eine neue Methode und ihre Carboni M, Ricci C. Thoracoscopic resection of medi- Auswirkungen auf die Narkose. Geburtshilfe Frauenheilkd astinal cystic schwannoma. Surg Endosc 1993; 7: 447–449. 1993; 53: 258–260. 53. Detter C, Reichenspurner H, Boehm DH et al.41. Kieturakis MJ, Nguyen DT, Vargas H, Fogarty TJ, Minimally invasive direct coronary artery bypass graft- Klein SR. Balloon dissection facilitated laparoscopic ing (MIDCAB) and off-pump coronary artery bypass extraperitoneal hernioplasty. Am J Surg 1994; 168: grafting (OPCAB): two techniques for beating heart 603–607. surgery. Heart Surg Forum 2002; 5: 157–162.42. Andersson L, Lindberg G, Bringman S, Ramel S, 54. Steiner W, Ambrosch P. Endoscopic Laser Surgery of the Anderberg B, Odeberg Wernerman S. Pneumoperito- Upper Aerodigestive Tract: With Special Emphasis on neum versus abdominal wall lift: effects on central Cancer Surgery. 2nd edition. New York: Thieme Medical haemodynamics and intrathoracic pressure during Publisher, 2001.
PHYSIOLOGY 2The physiological consequences of laparoscopic– Cholecystectomy is one of the most common laparo-endoscopic surgery are primarily due to the effects of scopic operations, and a discussion of the effects ofincreased intra-abdominal pressure (IAP) and the laparoscopic surgery on the circulation should besystemic absorption of the insufﬂated gas. The mag- begin with this operation that is typically performednitude of these changes is modulated by the position with the patient in the reverse Trendelenburg, head-of the patient and the choice of insufﬂation gas. up position. Joris and co-workers1 describe theOperations in the peritoneum, uterus or bladder typical haemodynamic course of a laparoscopic chole-require active expansion of the pre-existing cavity by cystectomy in healthy patients in a 15–30° head-upthe application of exogenous pressure. This is usually position. After induction of anaesthesia in the supineunnecessary for thoracoscopy, where the self-retracting patient, there is usually a parallel reduction of CO andtendency of the lungs is exploited and reinﬂation of the mean arterial pressure (MAP). Changing from thelungs is prevented by a selective ventilation, such as supine to the reverse Trendelenburg position induceswith a double-lumen endotracheal tube. In operations a further fall in blood pressure and CO accompaniedon organs surrounded by connective tissue, such as in by a decrease in right and left ventricular ﬁlling pres-the retroperitoneum (nephrectomy, adrenalectomy, sures, measured as right atrial pressure (RAP) andlymphadenectomy), the groin (hernia repair), or in the pulmonary capillary wedge pressure (PCWP).2mediastinum, an artiﬁcial cavity must be created with Inﬂating the abdomen with the patient in this posi-insufﬂated gas or with the aid of a dilation balloon. The tion causes an initial increase in MAP, RAP andspeciﬁc effects of these measures will occur in addition PCWP with a decrease in CO. Systemic blood pres-to the already ongoing changes resulting from anaes- sure gradually returns to the baseline level at anaes-thesia and surgery. thesia induction, RAP and PCWP increase to above their initial levels, while CO decreases still further.Circulation There is a sharp rise in peripheral systemic vascular resistance (SVR), which is partly responsible for theDuring laparoscopic surgery, the circulation under- observed increase in blood pressure. The changes ingoes typical changes of cardiac output (CO), blood MAP and central venous pressure (CVP) are signiﬁ-pressure, venous pressure and cardiac ﬁlling pressures cantly less when the abdominal cavity is expandedthat are the result of the complex interactions between with an external lift and not by increasing IAP.3,4anaesthesia, patient position, pressure changes in the This situation lasts only for about 15–20 min, afterbody cavities and neuroendocrine reactions. Depend- which CO returns to the baseline level before insufﬂa-ing on the circumstances, the effects of these factors tion, blood pressure remains constant, and SVRcan either reinforce each other or they can cancel each decreases slightly, while RAP and PCWP still remainother out. elevated. Since the reduction of CO lasts only such aIncreased IAP and the patient’s position (supine, short time, it may be easily missed if measurementshead-down Trendelenburg, or head-up reverse are not timed properly. This could be a reason for theTrendelenburg) are – given constant arterial carbon contradictory results of various studies. Figure 2.1dioxide (CO2) tension – the main determinants gov- summarizes the behaviour of CO in the studies oferning circulatory changes during laparoscopy. These Joris et al.1 and Reid et al.5 The reasons for the grad-two factors must be considered separately, since ual normalization of CO are not entirely clear. Somethey can either reinforce or oppose each other, depend- authors see it secondary to a reduction in afterload,ing on body position. If ventilation is not adjusted while others consider positive inotropic effects subse-properly, CO2 retention will occur causing initial quent to sympathetic nervous system activation bystimulation and then, ultimately, depression of the absorbed CO2 to be the decisive factor. As describedcirculation, depending on the extent of the resulting in more detail below, CO does not recover if nitroushypercapnia and acidosis (see the following text). oxide (N2O) rather than CO2 is used for insufﬂation.
8 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY This argues in favour of hypercapnia-induced activa- Joris et al. Joris et al. tion of the sympathetic nervous system as the force Reid et al. Reid et al. driving haemodynamic normalization.160 The increases in RAP and wedge pressure measured140 against atmosphere are the consequence of increased IAP, an increase which is transmitted into the thorax.4120 Systolic blood pressure This should not automatically be assumed to reﬂect100 (mmHg) a rise in cardiac ﬁlling, since in the Trendelenburg 80 position, intrathoracic pressure increases to an equal or even greater extent, so that effective transmural 60 atrial pressures may even decrease4 (Table 2.1). This 40 CO is supported by the echocardiographic study of (% change) Cunningham et al.,6 which shows a decrease in end- 20 diastolic left ventricular volume. In the head-up posi- 0 tion, gravity-induced reduction of venous returnϪ20 causes the initial decrease in CO. Increasing IAP during pneumoperitoneum reduces blood ﬂow in the Before induction After induction After positioning 5 10 15 20 30 After deflation inferior vena cava with venous congestion and blood Pneumoperitoneum (min) pooling in the lower extremities and a further reduc- tion in cardiac ﬁlling volumes (Figure 2.2).7,8 A more recent model uses the Starling resistor concept toFigure 2.1 Postoperative CO changes after laparoscopic explain the behaviour of pressures and blood ﬂow incholecystectomy. Relative changes after induction of anaes- the intrathoracic and intra-abdominal inferior venathesia and positioning of patient as well as at various timesafter begin of pneumoperitoneum (PP) are shown. For ease cava.9 Elevated IAP in patients with ascites is knownof comparing the two studies the value determined after to cause narrowing of the cephalad portion of thethe patient had been positioned was deﬁned as 100%.1,5 intra-abdominal vena cava,10 and this is also observed during pneumoperitoneum.11 Increasing IAP in Table 2.1 Changes in right atrial ﬁlling pressures in animal studies and in patients after creation of pneumoperitoneum under different conditions. There is a consistent reduction of transmural pressures that reﬂects reduced cardiac ﬁlling A. Studies in dogs after creation of pneumoperitoneum with CO2 or N2O with different IAPa Duration (min) 0 5 10 15 20 25 IAP (mmHg) 0 20 20 30 40 0 Right atrial pressure (RAP) CO2 6.5 Ϯ 3 12.5 Ϯ 7 14.3 Ϯ 8 14.6 Ϯ 9 15.9 Ϯ 11 6.0 Ϯ 3 N2O 6.0 Ϯ 3 13.1 Ϯ 7 13.0 Ϯ 9 14.1 Ϯ 8 16.8 Ϯ 11 6.4 Ϯ 3 Intrathoracic pressure CO2 3.8 Ϯ 2 11.6 Ϯ 6 12.8 Ϯ 5 14.0 Ϯ 6 15.1 Ϯ 7 3.9 Ϯ 2 N2O 3.8 Ϯ 2 11.6 Ϯ 6 12.2 Ϯ 7 13.1 Ϯ 9 15.9 Ϯ 10 4.5 Ϯ 2 Transmural atrial pressure (RAPtm ) CO2 2.7 Ϯ 1.2 0.9 Ϯ 0.5 1.5 Ϯ 0.9 0.6 Ϯ 0.3 0.9 Ϯ 0.5 2.1 Ϯ 1.2 N2O 2.2 Ϯ 1.1 2.1 Ϯ 1.1 0.8 Ϯ 0.3 1.0 Ϯ 0.5 0.9 Ϯ 0.4 1.9 Ϯ 0.9 B. Patients in reverse Trendelenburg position and CO2 pneumoperitoneum with constant IAP of 14 mmHg.b Intrathoracic pressure increased (⌬ITP) during the study Duration (min) 0 5 15 30 0 RAP 5.0 11.0 10.0 10.0 8 ⌬ITP 0 9.4 9.6 8.7 0 RAPtm 5 1.6 0.4 1.3 8 a Adapted from Ivankovich et al.26 b Adapted from Joris et al.1
PHYSIOLOGY 9 250 the circulatory effects of CO2 pneumoperitoneum in the head-up position are shown schematically in Figure 2.3. 200 Pneumoperitoneum has been shown to induce or to worsen valvular regurgitation.18 Increased SVR duringBaseline (%) 150 RAP IVCF pneumoperitoneum, preoperative hydration and head- RAP transmural down positioning are thought to be causal factors. 100 The situation in the Trendelenburg position with 50 increased IAP differs from that in the head-up posi- tion, and the circulatory responses deviate in several 0 important aspects from those described so far. The 0 5 10 15 20 30 min forces of gravity and IAP that act synergistically in the Baseline 20 20 30 40 0 mmHg head-up position to reduce cardiac ﬁlling, oppose each Measurement points other in the head-down position. In the Trendelenburg position, CO either remains constant or can evenFigure 2.2 Changes of IAP and blood ﬂow in the inferiorvena cava (IVCF). RAP increases with increasing IAP (abscissa). increase.19–21 Kelman reports, for example, that theHowever, transmural ﬁlling pressure (RAPtm) decreases signiﬁ- IAP of 15 mmHg normally used for pneumoperi-cantly, while IVCF is also reduced. (Adapted from Ref .) toneum caused an increase in CO, and that CO only decreased when IAP was elevated to 40 mmHg or higher.19 One of the reasons for the lack of CO reduc- tion is that transmural atrial pressures (RAPtm, LAPtm)study animals by the intraperitoneal instillation of remain unchanged or even increase slightly (Table 1.2)normal saline solution established a pressure gradi- during insufﬂation with an IAP of 15–20 mmHg in theent between the intra- and extrathoracic portions of head-down position, and there was thus no reductionthe inferior vena cava.12 Clinical studies in patients of left ventricular end-diastolic volume.6undergoing laparoscopic cholecystectomy showedthat increasing IAP also increases the pressure gradi- On the other hand, Lenz et al.22 and Johannsen et al.23ent between intrathoracic and intra-abdominal vena reported a decrease in CO of approximately 20%, evencava pressures.9 A rise in IAP as occurs during pneu- though RAPtm remained constant. These contradic-moperitoneum will impair venous return through the tory results, however, might be due to methodologicalinferior vena cava. Blood ﬂow into the thorax will short-comings, since CO was measured in these stud-cease whenever transmural pressure across the wall of ies by bioimpedance, a method that might have a sys-the vein falls to zero or below. Evidence that this actu- tematic error under the given study conditions. Theally occurs is given by the observation that blood ﬂow in bioimpedance method measures changes in a high-the femoral vein is slowed and ceases intermittently in frequency signal applied to the thorax with electrodespatients undergoing laparoscopic cholecystectomy.13,14 on the upper and lower thorax aperture. Given a con- stant thorax geometry, changes in the signal reﬂectReduction of cardiac ﬁlling is seen as the primary cause changes in the impedance (Z) assumed to be due toof reduced CO. This view is supported by observations ﬂuctuations in intrathoracic blood volume. Strokein animal experiments, in which CO changed only volume (SV) is calculated from the cyclic impedanceslightly in normovolaemic animals, but fell markedly changes by applying the functionwhen they were hypovolaemic. In over-infused, hyper-volaemic animals, on the other hand, CO increased dZ Ϫ1 SV ϭ f (L3 ) Zby ca. 50% over the baseline values.15 On the other dt 0hand, Gentili and co-workers presented circumstantial or, with older systems, with the functionechocardiographic evidence suggesting myocardialdysfunction during laparoscopy in children.16 During 2 moderate pressure pneumoperitoneum with an IAP of L dZ SV ϭ f 10 mmHg or less, left ventricular end-diastolic volume Z 0 dt min increased without the concomitant increase of left ven-tricular ejection fraction that one might expect accord- The distance between the upper and lower electrodesing to the Frank–Starling mechanism. Body position (L) enters into the calculation to the third or seconditself has an important inﬂuence on CO. In animal power, so that minor deviations in the distance betweenstudies, the head-up position caused a further decrease the electrodes result in large errors. For example, a 6%in CO, while the Trendelenburg position led to a partial decrease in L results in a 17% reduction in the calcu-normalization.17 The interdependent factors governing lated SV. A deviation of this magnitude is conceivable
10 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Head-up CVP ↓ position PCWP ↓ ITP ↓ CVP ↓ PCWP ↓ ITP ↓ RAPtm ↓ Cardiac ↓ IAP ↑ IVCF ↓ CO ↓ LAPtm ↓ filling AVP ↑ SVR ↑ MAP ↑ (a) NA ↑ CVP ↓ Head-down PCWP ↓ position ITP ↓ CVP ↓ PCWP ↓ ITP ↓↓ RAPtm Cardiac ↑→ ↑→ CO ↑→ LAPtm filling IAP ↑ IVCF ↓ AVP ↑ SVR ↑ MAP ↑ (b) NA ↑Figure 2.3 Haemodynamic changes during pneumoperitoneum with CO2: (a) in head-up reverse Trendelenburg position,or (b) in head-down Trendelenburg position. T: Trendelenburg position; rT: reverse Trendelenburg head-up position; ITP:intrathoracic pressure; AVP: vasopressin; NA: norepinephrine; ↑increase; ↓decrease; ↑→ no change or only slight increase.(For abbreviation see text.)in the head-down position and with increased IAP, of norepinephrine, vasopressin and renin–angiotensin,since the combined effects of gravity and pneumoperi- and consequently elevated SVR and not changes intoneum would widen the lower thorax aperture and stroke volume are responsible for blood pressurewould thus bring the upper and lower electrodes closer changes (see Section on stress reactions).together. Moreover, the basic impedance of the thorax,Z0, will also be altered to an unknown degree by the Cardiovascular changes during pneumoperitoneumshift of diaphragm, liver, spleen and other abdominal are not only due to the increased IAP, but are alsoorgans into the measurement area. Using only a very caused by the systemic effects of the absorbed CO2low IAP (5–8 mmHg) and taking the altered baseline and the vegetative reactions to peritoneal irritation.impedance into the equation, as in the study by Ekman The studies cited so far only investigated the cardio-et al.,24 the bioimpedance method yields results similar vascular effects of CO2 as insufﬂation gas, but usingto those of the dye dilution method. This problem is N2O for inﬂation instead of CO2 changes the patternperhaps not as relevant in the head-up position, since of cardiovascular effects. Comparing the results ofthe effects of gravity and the pneumoperitoneum tend these studies helps to delineate the causative factors.to balance each other out.25 Ivankovich and co-workers directly compared theThe blood pressure and peripheral vascular resistance haemodynamic changes induced by a pneumoperi-responses to inﬂation of the abdomen with CO2 are toneum with either CO2 or N2O in dogs.26 Althoughthe same whether the patient is in a supine position, they described the changes as essentially identical, theyhead-down Trendelenburg position or in a head-up did observe that after 20 min at an IAP of 20 mmHgposition, despite the fact that the change in CO is CO had decreased by 57% with CO2 and by only 47%totally different. This suggests that neuroendocrine with N2O, while vascular resistance had increased bystress responses with increased plasma concentrations 148% with CO2 and only by 93% with N2O (Table 2.2).
PHYSIOLOGY 11 Table 2.2 Haemodynamic effects of pneumoperitoneum using either CO2 or N2O as insufﬂation gas Author Position Gas ⌬CVP ⌬CO ⌬MAP ⌬SVR (% or mmHg) (%) (%) (%) Ivankovich dogs26 Supine CO2 – Ϫ57 ϩ11 ϩ148 N2O – Ϫ47 ϩ7 ϩ93 Rademaker27 Head-up CO2 Ϫ50 (6 → 3) Ϫ31 0 ϩ45 N2O Ϫ40 (5 → 3) Ϫ40 Ϫ33 ϩ12 Marshall20,28 Head-down CO2 ϩ38 (8 → 11) Ϫ0.7 ϩ26 ϩ25 N2O ϩ25 (8 → 10) Ϫ23 ϩ17 ϩ49 Changes are given between baseline values after induction of anaesthesia and the value in the described position after creating the pneumoperitoneum. Note: Changes in CVP (⌬CVP) do not necessary indicate a change in right atrial ﬁlling pressure.Unfortunately, the authors did not test their data for sympathetic nervous system with increases of heartstatistical signiﬁcance. rate, vascular resistance and CO.32–34 Figure 2.4 gives a synopsis of these interactions. A study in childrenThe results of a comparative study by Rademaker showed that pneumoperitoneum without hypercapniaet al.27 on patients undergoing cholecystectomy carry caused left ventricular regional wall movementmore weight. They observed a reduction of CO in abnormalities.35both the CO2 as well as the N2O group, but when thepatients were in the reverse Trendelenburg position, An increase in SVR, often combined with a coincidentthe reduction in the group with N2O was signiﬁcantly increase in MAP is a constant observation in virtuallygreater. At the same time, MAP and SVR were all investigations, while simultaneously measured COmarkedly higher in the CO2 group (Table 2.2). exhibited no consistent relationship with blood pres-Marshall et al. made similar observations using dye sure. The clinical relevance of this fact is that duringdilution in patients in the Trendelenburg position.20,28 laparoscopy one cannot make any inferences about theCO exhibited a varying response during inﬂation with cardiac pump function or perfusion from the arterialCO2: it increased in two patients, decreased in two blood pressure. An increase in afterload also has thepatients and remained constant in three patients. inherent risk of precipitating cardial decompensationDuring inﬂation with N2O, CO decreased in all in patients with congestive heart failure. Intravenouspatients by approximately 23% (Table 2.2). Blood nitroglycerine has been used to decrease SVR duringpressure rose in both groups but the increase was laparoscopy and restore haemodynamic function.36,37greater in the CO2 group (26%) than in the N2O The consistently occurring blood pressure increase thatgroup (17%). is usually accompanied by tachycardia, indicates an.One can see from the results of these studies that increase in myocardial oxygen consumption (MVO2).38using CO2 as the insufﬂation gas can partially alleviate The marked rise in the concentration of circulatingthe negative effects of increased IAP on CO. This catecholamines is associated with an increase in themight be due in part to the stimulatory effects of inotropic state. of the myocardium and an furtherabsorbed CO2 on the sympathetic nervous system, increase of MVO2. The combination of these factorssince there was no attempt to maintain normocapnia can compromise patients at cardiovascular risk. Circu-in any of the studies.29 However, a different study latory collapse and dysrhythmias also deserve mentionclaims to have found no effect of normocapnia or as relevant adverse cardiovascular events. These can behypercapnia on blood pressure behaviour.30 interpreted as resulting either from the activation of the sympathetic nervous system or from a vagal reactionPredicting the cardiovascular effects of absorbed CO2 to peritoneal stretching and intra-abdominal manipu-is hampered by the fact that it exerts manifold effects lation combined with reduced venous return.39–41on various segments of the circulation itself and onregulatory functions. Some of these effects directly A study in cardiac transplant patients undergoingoppose one another and some act synergistically. CO2 laparoscopic cholecystectomy is interesting, despitewith acidaemia can reduce myocardial contractility,31 the small number of patients.42 These patients did notbut in the intact organism this is more than com- have an increase in MAP or SVR after inﬂation of thepensated for by the CO2-induced activation of the abdomen, but only an increase of CVP. CO returned
12 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Vagus Ϫ Ϫ ϩ ϩ ϩ ϩ Sympathetic CO2 CO2 nervous system ϩ direct effects indirect effects ϩ ϩ Ϫ VasculatureFigure 2.4 Direct and indirect cardiovascular effects of CO2 absorbed during laparoscopic surgery. CO2 has a negativeinotropic effect on the myocardium, stimulates adrenal medullary catecholamine release and cause vasodilation. These directeffects are cancelled out to a large extent by indirect effects, such as stimulation of the sympathetic nervous system andinhibition of parasympathetic innervation.to normal after inﬂation and remained constant at Regional blood flowpreoperative levels. These observations were basicallycorroborated by another study.43 Case reports have Increased IAP not only inﬂuences global haemo-also shown that laparoscopic surgery is uneventful in dynamics but interferes also with the blood ﬂow toheart transplant recipients.44,45 individual organs. Alterations of regional perfusion can cause problems independent of total blood ﬂow, such Note Inﬂating the abdomen with CO2 typically causes as impairing organ function or altering drug delivery an increase in peripheral vascular resistance and a com- and disposal. pression of the atria with a reduction of cardiac ﬁlling. Studies with transcranial Doppler sonography (TCD) The initial response to this is: showed that CO2 pneumoperitoneum increased blood • Increase in arterial blood pressure ﬂow velocity in the middle cerebral artery.46 This was • Decrease in CO probably not due to the increase in IAP but to a rise in • Increase in CVP arterial CO2 tension, since other authors could not • Increase in left ventricular wall tension . conﬁrm an effect of increased IAP on cerebral blood • Increase in MVO2 ﬂow when arterial CO2 tension was kept constant.47,48 A further study demonstrated that arterial PCO2 was directly correlated with cerebral blood ﬂow.49 Note The position of the patient can either enhance or diminish the effect on CO: Increasing IAP by insufﬂating CO2 markedly reduces blood ﬂow in the portal vein, hepatic artery and supe- • Transient decrease with gradual recovery in reverse rior mesenteric artery,50 although in one study, ﬂow in Trendelenburg position (e.g. during cholecystec- tomy and other upper abdominal operations) the hepatic artery remained unchanged.51 Inﬂating • No change or slight increase in Trendelenburg posi- with helium (He) causes a more marked decrease in tion (e.g. during gynaecological or urological opera- hepatic blood ﬂow than CO2.52 The sum effect was a tions, transperitoneal hernia repair) reduction in indocyanine green clearance.53 Intestinal mucosal perfusion is reduced as well and possible mucosal ischaemia is suggested by the decrease of Note Increased abdominal pressure causes conges- intramural pH in the jejunum.54,55 A more recent study tion and stasis in the veins of the legs, particularly with suggests that insufﬂated CO2 enhances splanchnic the patient in the reverse Trendelenburg position. blood ﬂow up to an inﬂation pressure of 16 mmHg.56 One recent study showed that hepatic blood ﬂow can be This leads to: Risk of deep vein thrombosis and requires affected to a degree that impairs hepatocyte integrity rapid postoperative mobilization and thrombosis prophylaxis. depending on the nature of the operation and patient position. Laparoscopic cholecystectomy caused greater
PHYSIOLOGY 13postoperative increases in alcohol dehydrogenase, glu- The observed reductions in renal and hepatic perfu-tathione S-transferase, aspartate aminotransferase and sion can affect the elimination of drugs used foralanine aminotransferase than laparoscopic colectomy anaesthesia, for example, by reducing their clearance.reﬂecting signiﬁcant hepatic hypoperfusion during It is conceivable that the half-lives of both hepaticallycholecystectomy.57 as well as renally eliminated substances could be pro- longed by laparoscopic surgery. Reduced indocyanineThe data on the effects of laparoscopy on renal green clearance during pneumoperitoneum supportsfunction show that urine output, renal blood ﬂow and this assumption.53creatinine clearance are reduced during pneumoperi-toneum.55,58,59 One study suggested that it was not The effect of CO2 pneumoperitoneum on uterineelevated IAP per se that it is responsible for the blood ﬂow is of particular importance wheneverobserved effects on urine ﬂow, but that intraperi- laparoscopic surgery is to be performed during preg-toneal cooling might possibly also be involved, since nancy. In gravid ewes, CO2 pneumoperitoneum signi-the changes were not observed when warm gas was ﬁcantly reduced uterine blood ﬂow, increased maternalused for insufﬂation.60 This does not seem likely in and foetal CO2 tensions and caused maternal and foetalview of the results of numerous other investigations acidosis.72 A different study showed that uterine bloodthat give strong evidence that pressure itself and not ﬂow remained unaffected if partial pressure of CO2 inthe insufﬂated CO2 or its temperature is the probable arterial blood (PaCO2) was kept constant.73 Contrary totrigger. In one animal study, renal function deterio- these results, He pneumoperitoneum reduced uterinerated when IAP was increased with an inﬂatable bag blood ﬂow without altering arterial CO2 tension orinserted into the peritoneal cavity,61 and in another, blood pH, indicating that pressure is an independentrenal blood ﬂow and diuresis were both signiﬁcantly factor.74 Hypercapnia is known to independentlyreduced by directly compressing the kidney to a pres- reduce uterine blood ﬂow75 and the combination ofsure of 15 mmHg.62 Some clinical studies showed IAP and elevated PaCO2 might enhance the deleteriousonly inconsistent effects on renal function of patients: effects on the foetus.urine output and creatinine clearance were reduced inonly 60% of the patients, and either not affected at allor even increased in the others,63 but the most com- Note The increased pressure in the pneumoperi-mon observation is that increased abdominal pressure toneum induces a reduction of splanchnic and renal blood ﬂow.signiﬁcantly reduces urine output and can even causeanuria.64 Clinical consequences:The primary effect of increased IAP is a decrease in • Reduction of hepatic perfusion might prolong half- life of drugs eliminated by the liverrenal venous blood ﬂow that can persist after pressure • Reduction of creatinine clearance and urine ﬂowis released.65 Renal cortical perfusion also decreases might reduce the clearance of drugs that are elimi-during pneumoperitoneum.66 This reduction in renal nated through the kidneysblood ﬂow is the most likely cause of the increasedplasma renin activity seen with laparoscopy (seebelow). Urine O2 tension decreases when abdominalexpansion is achieved by gas inﬂation but not when Insufflation gasthe abdominal wall is lifted mechanically.64 The fall inurine O2 tension is a consequence of renal vasocon- The choice of the gas used for insufﬂation is anstriction.67,68 Increased urinary levels of N-acetyl- important factor affecting the safety of laparoscopicbeta-D-glucosaminidase have been described,55,69 procedures and determining the character of thewhich reﬂect signiﬁcant renal parenchymal hypoxia physiological consequences. Once practitioners hadwith tubular damage that can ultimately lead to acute realized that the use of room air for insufﬂation car-tubular necrosis and acute renal failure in the predis- ried a high risk of fatal gas embolism, a large numberposed patient. There is a direct relationship between of gases, including O2, CO2, He and N2O were inves-reduced renal blood ﬂow, decreased urine O2 tension tigated as possible alternatives, and also employed inand the observed reduction in creatinine clear- the clinical setting. None of the gases were found to beance63,70 as was demonstrated in patients undergoing ideal, and each represented a compromise. The choicecardiac surgery.71 Some suggest that supporting urine of a particular gas will depend on the risk–beneﬁtﬂow with the use of diuretics or low-dose dopamine assessment of the individual advantages, disadvantagesmight be beneﬁcial,70 but the currently available data and adverse effects. The details required for this deci-are not sufﬁcient to generally recommend this.65 sion will be sketched in the following paragraphs.
14 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYFactors inﬂuencing the choice of insufﬂation gas are 20–50 ml is sufﬁcient to cause a fatal gas embolism.physicochemical properties, such as solubility, dif- The same applies for the even less soluble He (Tablefusibility and ﬂammability, as well as the pharmacolog- 2.3). The primary requirement of an insufﬂation gas isical effects after systemic uptake. Solubility determines thus high solubility. Although diffusibility itself is nothow much of the insufﬂated gas can be absorbed by the an important factor, the product of diffusibility andbody and how it behaves once in solution. Diffusibility solubility is thought to give a better indication of theis a characteristic that determines how fast the gas can relative risk of a gas than solubility alone.76,77follow a concentration gradient from one compartment N2O and CO2 have a much higher solubility in bloodto another. In the case of pneumoperitoneum one must and inadvertent intravascular application is thus muchkeep in mind that the gas passes from a gas phase to a less dangerous than with the gases mentioned above.liquid phase and not through a membrane from one Systemic absorption of N2O does not cause thegas phase to another. This is particularly important derangement of acid–base status as seen with CO2, butwhen considering He, N2O and CO2. He is highly dif- there are other problems associated with its use. Onefusible owing to the small size of its single atom, but it of these is the risk of intra-abdominal ﬁre or explosionenters the liquid phase only slowly since it is poorly that has been repeatedly described with its use.78–81soluble. N2O and CO2 are much larger molecules, but N2O is not ﬂammable itself but it supports the com-both have markedly higher diffusion coefﬁcients due to bustion of other materials, such as methane or hydro-their greater solubility (Table 2.3). What is the most gen sulphide that can escape into the peritoneal cavityimportant determinant of safety in an insufﬂation gas? from the intestinal lumen through small, inapparentRoom air, a mixture of nitrogen, oxygen, argon and lesions to the bowel (Table 2.4).other gases, is dangerous when used as an insufﬂation CO2 was substituted for air as insufﬂation gas towardsgas. All of the component gases are poorly soluble, and the end of the 1940s, mainly by the German gynaecol-should air enter the venous system directly, as can hap- ogists Lindemann and Semm, since it offers a numberpen during insufﬂation, the ensuing intravascular bub- of advantages over the alternative gases, foremostbles will not dissolve, but will collect in the right heart among them being its high solubility in blood.82–84and the pulmonary circulation. The small amount of This results from the fact that most of the CO2 in blood is not in simple solution, but has been reversibly converted into bicarbonate ions reducing CO2 partial Table 2.3 Physicochemical properties of insufﬂation pressure. An additional factor is its binding to haemo- gases globin. Studies on spontaneously breathing dogs have Gas Solubility Relative Relative shown that 50–100 ml/min of CO2 can be injected coefﬁcient (ml solubility diffusion directly into the femoral vein without cardiovascular gas per ml H2O (O2 ϭ 1) coefﬁcient consequences.83 However, the choice of anaesthetic, at 760 mmHg) (O2 ϭ 1) such as the use of N2O can markedly reduce the amount of CO2 that is tolerated.85 This must be taken CO2 0.57 24.0 20.5 into account during operations with a high risk of N2O 0.47 16.3 14.0 intravascular gas entrainment. The advantages of CO2 O2 0.024 1.0 1.0 as insufﬂation gas are its excellent solubility in blood N2 0.012 0.52 0.55 He 0.008 0.37 1.05 and its rapid uptake from cavities (Table 2.3). On the other hand, CO2 is not pharmacologically inert after Table 2.4 Biochemical and pharmacological properties and risk proﬁle of insufﬂation gases Biochemical Pharmacological effects Risk of Supports effects embolism combustion CO2 Acidosis Activation of SNS, direct Ϫ(ϩ) Ϫ circulatory depression, pain N2O Inert Narcosis Ϫ(ϩ) ϩ O2 Inert Inert ϩ ϩϩ N2 Inert Inert ϩϩ Ϫ He Inert Inert ϩϩ Ϫ SNS: sympathetic nervous system.
PHYSIOLOGY 15systemic uptake. CO2 absorption raises PaCO2 and versa). The speed with which absorption takes placecauses a respiratory acidosis that must be compensated depends on the absorbing surface. Uptake throughfor by increasing alveolar ventilation (see below). the thick, smooth and relatively poorly perfused peri- toneum is slower than from loose connective tis- sue.93–95 The amount of gas absorbed has a decisiveUptake of insufflated CO 2 inﬂuence on the manner and magnitude of the physi- ological consequences.CO2 absorption is a further consistent characteristicof laparoscopic surgery that has an impact both on Despite high solubility and ease of tissue penetration,physiological consequences as well as on the manage- only a fraction of the insufﬂated CO2 is absorbedment of anaesthesia.86,87 One study found a high CO2 from the abdominal cavity. The amount can be esti-tension in the epigastric veins draining the peri- mated using data typical for laparoscopic operations.toneum, gives additional support to the assumption Approximately 5 l of CO2 are required to create thethat CO2 uptake from the abdominal cavity actually is pneumoperitoneum. Using the formula for the CO2responsible for the observed increase in arterial CO2 storage capacity given above shows that this volume oftension.88 It causes respiratory acidosis, predisposes CO2 would acutely raise the arterial CO2 tension of ato cardiac dysrhythmias and has to be eliminated by 60 kg patient from 40 to 82 mmHg. In reality, PaCO2increasing minute ventilation. increases only about 9 mmHg during a 10–30 min operation in a patient ventilated mechanically with aThere are approximately 120 l of CO2 stored in the constant minute volume. This represents the uptakebody,89 most of it in the form of carbonates in the of approximately 1080 ml.bones or dissolved in lipids. Aqueous solutions containcirca 500 ml CO2 per litre. CO2 stores can be divided This is a rough estimate of CO2 uptake using theinto three compartments – fast, intermediate and slow – average storage capacity of the fast and intermediatethat differ in their equilibration times. Blood and compartments in a patient with constant alveolarorgans with high blood ﬂow, such as the brain, liver and ventilation. A more accurate determination can bekidneys constitute the fast compartment, while the made using indirect calorimetry to measure theintermediate compartment comprises muscle and less increase in the volume of CO2 eliminated through thewell-perfused parenchymal organs. The CO2 tension lungs during CO2 insufﬂation. During the measure-in the fast compartment lies only slightly higher than ments, arterial CO2 tensions must be kept constant topartial pressure of CO2 in alveolar gas (PACO2) and ensure that absorbed CO2 is completely eliminatedrapidly follows any change in arterial PaCO2. The and not allowed to enter the storage compartments.intermediate compartment is relatively large and less This requirement is crucial since CO2 uptake will besensitive to ﬂuctuations of arterial CO2 tension – acute underestimated considerably if a relevant amount ofhyper- or hypoventilation has little effect on CO2 ten- the absorbed CO2 is stored (as evidenced by ansion in the muscles. These two compartments have a increasing PaCO2 or partial pressure of CO2 at end-total storage capacity of approximately 2 ml of CO2 per tidal (PetCO2)) then. A constant PaCO2 reﬂects thekg body weight and mmHg PaCO2 in a normal individ- fulﬁlment of this requirement, although in mostual.90–92 This means that the uptake of 2 ml of CO2 per studies arterial tension is not measured directly, andkg will raise arterial CO2 tension by 1 mmHg end-tidal CO2 concentrations (PetCO2) are used as a surrogate parameter.CO2 storage ml CO2 . ϭ One obtains the rate of CO2 absorption (VCO2 absorb) capacity (kg body weight)(mmHg Pa CO2 ) by subtracting the endogenous CO2 production . . (VCO2 endog) from the total exhaled CO2 (VCO2 total)Adipose tissue, bones and other tissues with low blood (Equation (2.1)):flow comprise the slow compartment. The storagecapacity of this compartment is approximately 10 mlCO2 kgϪ1 mmHgϪ1 PaCO2. The slow compartment is & & & VCO2 absorb ϭ VCO2 total Ϫ VCO2 endog (2.1)in close contact with the fast compartment, but trans-fer of CO2 between them is slow. This is due to thelow blood ﬂow in adipose tissue, while in bones the Endogenous CO2 production can be. continuouslylimiting factor is the conversion of CO2 to hydroxy- calculated from total body O2 uptake (VO2) using theapatite and vice versa. respiratory quotient (R):Due to its high diffusion coefﬁcient CO2 can easily & &pass from gas-ﬁlled cavities into the blood (and vice VCO2 endog ϭ VO2 R (2.2)
16 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Table 2.5 CO2 output und O2 uptake (ml minϪ1) Author CO2 output ⌬CO2 O2 uptake Preoperative Intraoperative Maximum Preoperative Intraoperative 97 Lewis et al. 102 126 – 24 – – Blobner et al.101 145–180 179–222 – – – – Kazama et al.87 110 Ϯ 24 163 Ϯ 26 – 54 Ϯ 16 129 Ϯ 26 142 Ϯ 26 Luiz et al.108 156 Ϯ 24 216 Ϯ 35 – – 206 Ϯ 15 211 Ϯ 23 Mullett et al.93 Intraperitoneal 132 176 – – – – Extraperitoneal 133 207 – – – – Puri and Singh199 3.6 Ϯ 0.51 4.4 Ϯ 0.56 – – – – (ml kgϪ1) (ml kgϪ1) Seed et al.96 135 151 – 16 – – Sumpf et al.95 Extraperitoneal 161.0 331.9 788 153.4 226.9 250.9 Transperitoneal 154.4 222.2 300.2 59.2 220.4 232.0 Tan et al.200 146 Ϯ 20 183 Ϯ 17 – 42.1 Ϯ 17 169 Ϯ 13 164 Ϯ 18 Weyland et al.98 138 Ϯ 29 212 Ϯ 50 361 – 201 –Older studies give an average CO2 uptake of over baseline during an uncomplicated transperitoneal20 ml minϪ1.96,97 These data were gathered during laparoscopic herniotomy ranges between 55% andshort diagnostic laparoscopic procedures without 70%.93,95,104 The highest absorption rate is seen duringregard to maintaining endogenous CO2 stores at a extraperitoneal procedures complicated by subcuta-constant level. More recent studies, in which care was neous emphysema, since the absorbing surface area istaken to keep PaCO2 constant, give much a higher very large and the tissue thickness through which theuptake (Table 2.5) and have helped deepen our under- gas has to diffuse is shorter (Figure 2.6).93,95,105–107standing of the physiological and physical events Chiche and co-workers found that CO2 eliminationduring CO2 uptake.87,95,98 was only 16.9% above baseline in patients without sub- cutaneous emphysema, while this complication causedCO2 uptake from the abdominal cavity does not an increase to 70%.105 We found an increase in CO2proceed at a constant rate, but is a function of capil- uptake of more than 500 ml minϪ1 in patients withlary perfusion in the peritoneum and the prevailing extensive subcutaneous emphysema during extraperi-pressure gradient. CO2 uptake initially increases toneal hernia repair, which corresponds to a relativewith rising IAP, but there is indirect evidence that increase of 250% compared to patients withoutfurther increasing IAP reduces capillary perfusion emphysema95 (Table 2.5).and decreases the rate of CO2 absorption.99–101 Therate of CO2 absorption during laparoscopic cholecys- The absorbed CO2 must be eliminated by increasingtectomy varies widely from patient to patient and can alveolar ventilation, since large PaCO2 increases causebe increased by a factor of three over baseline values considerable pH and electrolyte shifts. The latter are(Table 2.5). The absorption rate can also vary widely associated with an increased incidence of cardiovascu-during the course of the operation as shown in lar complications such as hypertension and cardiacFigure 2.5. dysrhythmias. The relative increase in ventilation thatOne consistent observation is that CO2 uptake depends was necessary to maintain normocapnia varied betweenon the tissue surface that is in contact with the gas 0% and 145% in one study. The corresponding meanphase, and therefore to a large degree on the type of absolute increase in minute volume was 14–16 loperation.93,94 Absorption is low during laparoscopic minϪ1.98,108 Debois and co-workers observed that ven-operations without further damage to the smooth, tilation had to be increased by an average of 30% dur-tough and relatively thick peritoneum. Opening the ing laparoscopic cholecystectomy, while an increase ofperitoneum for dissection into the surrounding con- 55% was required during endoscopic hernia repair.104nective tissue, or even the creation of artiﬁcial cavities Our own data show that ventilation has to be increasedas for nephrectomy or preperitoneal herniotomy, can by more than 400% in patients with extensive subcuta-enlarge the exposed surface area and enable a higher neous emphysema. The corresponding absolute valueabsorption rate.94,102,103 The increase in CO2 uptake of minute volume was 30 l minϪ1.95
PHYSIOLOGY 17 700 ml minϪ1 600 500Exhaled CO2 400 Figure 2.5 CO2 absorption 300 during the course of laparo- scopic extraperitoneal inguinal 200 hernioplasty. One can easily see that the amount of absorbed CO2 does not remain constant, 100 but increases during the opera- tion. The highest values are seen 0 postoperatively and are proba- 0 10 20 30 40 50 60 70 80 90 98 108 bly due to the extensive subcu- Intraoperative Postoperative taneous emphysema. (Adapted min from Ref .) Ϫ1 account when drawing up the list of possible con- 250 ml min traindications for laparoscopic surgery. Gynaecological laparoscopy Laparoscopic cholecystectomy There is a constant risk of hypercapnia in the sponta- Retroperitoneale pelviscopy neously breathing patient, as is shown in Table 2.6. This is not entirely due to suppression of ventilatoryEliminated CO2 200 drive by the anaesthetic as the data obtained using Start of surgery N2O as insufﬂation gas show. But mechanical ventila- tion alone does not guard against hypercapnia if is not adapted to the rate of CO2 absorption. Thermocautery and laser surgery produce high intra- 150 Postoperative abdominal concentrations of carbon monoxide. This can be absorbed from the peritoneum and induce relevant levels of carboxyhaemoglobin.109,110 1h 100 NoteFigure 2.6 The magnitude of CO2 absorption depends on • CO2 absorption varies widely, both between patientsoperation site. (Adapted from Ref .) The gynaecological as well as during a single operationlaparoscopy were short diagnostic or operative procedures, • It is greatest during surgery outside the borders ofsuch as tubal ligation. The pelviscopic operations were anatomically deﬁned cavities with insufﬂation of gasretroperitoneal lymphadenectomy. Arterial CO2 tensions into loose connective tissue (e.g. lymphadenectomy,were not kept constant so the actual amount of CO2 uptake herniotomy, nephrectomy)might be signiﬁcantly higher. • Minute ventilation required to maintain normocap- nia during these operations can increase by more than 20 l minϪ1It is important to be aware of the expected magnitude • Capnometric or blood gas monitoring is indispensa- ble in order to detect the PaCO2 increase and toof CO2 uptake, since the increase in alveolar ventila- adapt ventilationtion required to maintain normocapnia might not bepossible in patients with severely compromised lung Clinical conclusionfunction. This is an aspect that cannot be ignored,considering the number of elderly patients with • Patients with compromised pulmonary function and reduced ventilatory reserve (e.g. COLD or after lungchronic obstructive lung disease (COLD) who might resection) are at a higher riskpresent for laparoscopic surgery. It must be taken into
18 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Table 2.6 Changes of PaCO2 and PaO2 during pneumoperitoneum with N2O or CO2 Mode of ventilation Author Gas FIO2 ⌬PaCO2 (mmHg) ⌬PaO2 (mmHg) Spontaneous breathing Baratz and Karis195 CO2 0.99 4.8 Ϫ20 Hodgson et al.196 CO2 – 7.0 – Lewis et al.97 CO2 0.98 4.6 – Scott and Julian41 CO2 – 17.6 – N2O – 5.9 – Keneﬁck et al.119 CO2 0.35 10.0 Ϫ29 Mechanical ventilation Alexander and Brown197 CO2 – 8.7 Ϫ24 N2O – Ϫ2.4 Ϫ28 Baratz and Karis195 CO2 0.99 1.1 Ϫ32 Hodgson et al.196 CO2 – 10.1 – Kelman et al.19 CO2 0.3 8.4 3 Motew et al.21 CO2 0.5 12.1 Ϫ6 Magno et al.198 CO2 0.3 9.0 Ϫ9 N2O 0.3 Ϫ1.0 Ϫ13 ⌬PaCO2 and ⌬PaO2 denote changes of the respective partial pressures between beginning and end of gas insufﬂation. FRC reduced by CC increased by From anatomical End tidal gas dead-spaceFRC Aging CC Lying down Smoking Anaesthesia Emphysema Exhaled air Obesity Pulmonary oedema Pregnancy Mixed venousFigure 2.7 Numerous conditions can bring the FRC within bloodthe range of CC, either by reducing FRC or by increasing CC. ∞ 1,7RESPIRATION 0,9Gas exchange 0,7Every operation in general anaesthesia is associatedwith characteristic intra- and postoperative alter-ations of lung function. Functional residual capacity 0(FRC) and total compliance (Ctot) decrease by anaverage of 20% and dead-space ventilation (VD/VT) V/Qincreases immediately after induction of anaesthesia.The magnitude of FRC reduction depends on the Arterialpatient’s build and can be 50% in adipose patients.111 bloodEven a moderate reduction of FRC can cause arterial Figure 2.8 Schematic diagram illustrating the variety ofO2 desaturation in patients with increased closing . . ventilation–perfusion ratios (V /Q.) present in the lung. VD/VT .capacity (CC), such as cigarette smokers and patients occurs in alveoli with a high V /Q ratio, whereas venous . .with COLD (Figure 2.7). These changes are associated admixture occurs in alveoli with a V /Q ratio below unity. A . .with the cessation of spontaneous breathing and insti- V /Q of zero indicates shunt perfusion.tution of mechanical ventilation.112–114 The ultimatecauses are a disturbance of the normal ventilation–perfusion relationship, the loss of dorsobasal diaphragm ventilation of the well-perfused basal regions with anmotion and the changes in intrathoracic pressures. increase in shunt perfusion (Q S/Q T), while the well-The ventilation–perfusion relationship is shifted in ventilated but poorly perfused superior regions (Westwide areas of the lungs (Figure 2.8), leading to reduced zone I) are responsible for the increase in VD/VT
PHYSIOLOGY 19 Starling–Resistor Weir model Side view PA upright PA Pa PV Pa PV Zone 1 No flow PA Ͼ Pa Ͼ PV Pa Zone 2 PA PA Pa Ͼ PA Ͼ PV Pa PV PV Flow is ƒ(PaϪPA) Zone 3 Pa PV Pa Ͼ PV Ͼ PA PA PA Pa PV Flow is ƒ(PaϪPV) Zone 1 PA Ͼ Pa Ͼ PV Zone 2 Pa Ͼ PA Ͼ PV Zone 3 Pa Ͼ PV Ͼ PA Side view supineFigure 2.9 The inﬂuence of gravity and the prevailing pressures in the lungs and pulmonary vessels lead to the develop-ment of areas with differing perfusion, which were divided by West into the zones 1–3. In zone 1, which is located in the api-cal portions of the lung in the upright subject or in the uppermost portions in the recumbent patient, alveolar pressure (PA)is higher than the pressure in the pulmonary capillaries (Pa). The capillaries collapse and blood ﬂow ceases. In zone 2, bloodﬂows as long as Pa is higher than PA, and stops intermittently during the cardiac cycle or due to increased alveolar pressureduring mechanical ventilation. In zone 3, which is in the dependent portions of the lungs, pulmonary venous pressure (PV) ishigher than PA, so that the capillaries never collapse and blood ﬂow is continuous. (Modiﬁed from West et al. J Appl Physiol1964; 19: 713–724.) Changes in blood pressure or intrathoracic pressure inﬂuence the distribution of the zones; increasingvascular ﬁlling and blood pressure reduces the extent of areas with zone 1 characteristics, and thus VD/VT whereas increasingintrathoracic pressure (e.g. during pneumoperitoneum) will increase PA and VD/VT.mentioned above (Figure 2.9). Dorsobasal atelectatic inﬂuence of elevated IAP with cephalad shift of theareas develop immediately after induction of anaes- diaphragm.116,117 Applying constant positive PAW canthesia that can be seen in computerized tomography largely prevent the FRC reduction,120,121 an observa-scans.112,114 The resulting alterations of pulmonary tion that has great practical value for the managementfunction are seen clinically as a decrease in arterial O2 of anaesthesia, since it improves gas exchange andand CO2 tensions as well as an increase in airway oxygenation.121,122pressure (PAW) during mechanical ventilation. These The changes observed in infants during pneumoperi-factors are obviously effective during laparoscopic or toneum differ from those in adults. These patientsthoracoscopic operations, and can be intensiﬁed by rely nearly completely on diaphragm motion for ven-the increase in IAP, head-down position or one-lung tilation due to the horizontal position of their ribs.ventilation.99,115–117 Even slight increases of IAP can cause a sharp dropAvailable data indicate that pneumoperitoneum in arterial O2 saturation that requires positive end-causes a further reduction of FRC (Table 2.6).115,118,119 expiratory pressure of nearly the same magnitude asOne would expect an effect of this nature under the IAP for compensation.123
20 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYIntraoperative pulmonary function Note Pneumoperitoneum induces a reduction ofCtot of the chest and lungs falls markedly after creation compliance, an increase of pulmonary shunt perfusionof the pneumoperitoneum, with the thoracic com- and VD/VT and the development of basal pulmonaryponent decreasing more than the pulmonary atelectases.one.115,118,124,125 In patients without lung pathology, The clinical consequences are:creating a pneumoperitoneum in the supine patientinduces a 43% drop in Ctot, which remains unchanged • PAW increase (cave barotrauma)when the patient is brought into a reverse • Total minute ventilation has to be increased just in order to keep alveolar constantTrendelenburg position.126 This position improves • Arterial O2 desaturation (PEEP ventilation recom-compliance and oxygenation in obese patients and mended, pulse oximetry required)patients with COLD.127,128 When the abdomen isinﬂated after the patient has been brought into thehead-up position the Ctot reduction is also between Postoperative pulmonary function32% and 48%.129,130 There is a large body of evidencethat abdominal inﬂation and not patient position is Laparoscopic surgery is thought to compromise lungresponsible for the compliance reduction.124,126,131 The function to a lesser degree than conventional open pro-change is also independent of the duration of the pneu- cedures.135–138 While the intraoperative alterations ofmoperitoneum and is rapidly reversible after IAP has lung function depend primarily on the patient’s posi-been released.130 The changes in American Society of tion and the ventilatory mode (spontaneous vs. con-Anaesthesiologists (ASA) III and IV patients are similar trolled), the postoperative changes are governed by theto those in their healthy counterparts with a compliance incision and the surgical site – upper vs. lowerdecrease of approximately 40%132 (Table 2.7). abdomen and intraperitoneal vs. extraperitoneal. After upper abdominal and thoracic surgery, there is a pro-The clinical correlate of reduced compliance is the rise longed reduction of VC, forced expiratory volumein PAW at otherwise unchanged respirator settings. (FEV1) and FRC.111 Reduced VC prevents effectivePlateau pressure increases between 45% and coughing and periodic deep breathing (sighing), FRC75%.108,130,132,133 The combination of low compliance can fall below CC, the lung volume at which airwayand increased minute volume can lead to unacceptably closure begins (Figure 2.7). This causes an increase ofhigh PAW and necessitate termination of the operation venous admixture and is responsible for late postoper-or conversion to an open procedure. A sudden, sharp ative hypoxaemia.139 These changes are not observedincrease in PAW should alert the anaesthetist to the pos- after lower abdominal or body surface surgery, or atsibility of a complication such as a pneumothorax.105,134 least not in this magnitude and duration. Lung func-Essentially the same respiratory changes are seen dur- tion is restricted by incision pain and increased tensioning thoracoscopy as during thoracotomy, which are a of the abdominal wall muscles as well as by a reﬂexconsiderable increase of shunt perfusion and a reduc- inhibition of inspiratory diaphragm motion.140–142 Thetion of vital capacity (VC). This can impede the nec- I:E relationship is shifted towards expiration, the ven-essary increase in minute ventilation. The effects of tilatory contribution of the diaphragm is sharplyextraperitoneal endoscopic procedures on lung func- reduced and there is a shift from abdominal to rib-cagetion are probably much less impressive. breathing (Figure 2.10).143 Ventilatory minute volume Table 2.7 Changes in thoracic and pulmonary compliance induced by pneumoperitoneum Author Compliance (ml/cmH2O) Position Baseline value After With pneumo- positioning peritoneum Drummond115 HD 60 61 44 Ϫ27% Johannsen23 HD 50 42 30 Ϫ40% Kendall124 HU 55 – 28 Ϫ49% (thorax) 102 – 62 Ϫ39% (lung) Luiz108 HU Absolute values not given Ϫ40% Weyland98 Supine 60 – 40 Ϫ33% HD: head-down position; HU: head-up position.
PHYSIOLOGY 21 Vthorax Vabdomen are not due to a residual pneumoperitoneum.145 A 100 greater degree of respiratory impairment is seen fol- lowing more extensive laparoscopic operations in the lower abdomen and pelvis, such as laparoscopic-Contribution (%) 80 assisted vaginal hysterectomy or laparoscopic-assisted prostatectomy.146 60 VC is reduced by approximately 24% during the ﬁrst 40 24 h after laparoscopic cholecystectomy, but by 52% in the same period following the conventional procedures 20 (Table 2.8). It returns to normal after 2 or 3 days after the laparoscopic operation, while it remains 0 depressed for a much longer period after the open Baseline 1 6 24 operation.137,147 Recovery of VC is delayed in older Hours after surgery patients (Figure 2.12).148 Our own data show that VC was reduced by 19% on the ﬁrst postoperative day,Figure 2.10 The incisional wound pain of laparoscopic but that this had resolved on day two.cholecystectomy causes a reﬂectory inhibition of diaphragmactivity with a change in the relative contributions of Twenty-four hours after surgery, FRC is reduced byabdominal and rib-cage breathing that is detectable 24 h 8% after laparoscopic cholecystectomy compared toafter surgery. (Adapted from Ref .) 27% after the conventional technique. The impairment is much more short-lived after the minimally invasive procedure, and resolves within 3 days, while FRC is Cholecystectomy still reduced by 23% at this time following the open ml mϪ2 minϪ1 Hernioplasty procedure (Figure 2.13).137 Other authors report sim- 400 40 ilar ﬁndings.149 The magnitude of arterial O2 desatu- 350 Vti 35 ration parallels FRC reduction, and postoperative Tidal volume index (Vti) hypoxaemia is much less severe following laparo- Respiratory rate (RR) 300 30 scopic operations. 250 25 Pneumonia is the most serious pulmonary complica- 200 20 tion of laparotomy. It can develop on the basis of an 150 15 intraoperative atelectasis perpetuated by impaired RR deep breathing and abolishment of effective coughing. 100 10 The incidence described in the literature varies 50 5 between 10% and 70% depending on how it is deﬁned in the individual study. It depends on the surgical 0 0 incision – upper or lower abdomen, midline vs. trans- Preoperative Postoperative verse vs. subcostal – and the diagnostic criteriaFigure 2.11 The postoperative respiratory changes of employed – clinical symptoms, blood gases or radi-tidal volume and respiratory rate depend on the intra- ographic signs. Hypoxaemia is a regular postoperativeabdominal location of the surgical site. Tidal volume feature even without clinical evidence of pneumonia.exhibits a greater decrease following laparoscopic cholecys- Pulmonary inﬁltrates are seen in up to 90% of alltectomy than after hernioplasty. Respiratory rate increases patients following conventional cholecystectomy, whileto a greater degree after cholecystectomy. (Adapted from the incidence was only 40% after the correspondingRef .) laparoscopic procedure (Figure 2.14).136 Only 10% of the patients with laparoscopic cholecystectomy devel- oped segmental atelectasis.136,149 An elevated rightremains constant but tidal volume is reduced by 30% hemidiaphragm is a common observation.144 A study inand respiratory rate is increased (Figure 2.11). These our hospital revealed a 50% incidence of pneumonia ineffects are observed after laparoscopic surgery, but patients with abdomino-thoracic oesophagus resec-depend on the intraperitoneal localization of the oper- tion.150 Pneumonia was deﬁned as the presence ofation site. Laparoscopic hernia repair and cholecystec- pulmonary inﬁltrates in chest X-ray and elevated bodytomy have virtually identical trocar insertion sites but temperature later than 24 h after surgery. The presencethe two operations can have very different effects on of this complication prolonged the median duration ofpostoperative diaphragm function.141,144 The effects intensive care from 8 to 15 days. Pneumonia is one of
22 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Table 2.8 Changes in lung function 24 h after laparoscopic (LC) or conventional open cholecystectomy (OC) Parameter LC (%) OC (%) P Source FVC Ϫ21 Ϫ50 Ͻ0.05 Schauer136 Ϫ28 Ϫ44 Ͻ0.05 Williams201 Ϫ26 Ϫ48 Ͻ0.05 Frazee202 Ϫ20 Ϫ45 Ͻ0.05 Putensen-Himmer137 Ϫ42 Ϫ71 Ͻ0.05 Rademaker170 Ϫ13 n.s. Johnson149 Ϫ25 n.s. Rotbøll Nielsen203 Ϫ23 n.s. Beebe146 Mean FVC ؊24 ؊52 FEV1 Ϫ24 Ϫ55 Ͻ0.05 Schauer136 Ϫ24 Ϫ45 Ͻ0.05 Williams201 Ϫ28 Ϫ47 Ͻ0.05 Frazee202 Ϫ16 Ϫ43 Ͻ0.05 Putensen-Himmer137 Ϫ22 n.s. Rotbøll Nielsen203 Ϫ26 n.s. Beebe146 Mean FEV1 ؊23 ؊48 TLC Ϫ8 Ϫ22 Ͻ0.05 Schauer136 Ϫ17 n.s. Rotbøll Nielsen203 MVV Ϫ22 Ϫ52 Ͻ0.05 Schauer136 FEFmax Ϫ19 Ϫ57 Ͻ0.05 Williams201 Ϫ33 n.s. Beebe146 FEF25–75 Ϫ19 Ϫ47 n.s. Frazee202 FRC Ϫ15 Ϫ27 n.s.* Putensen-Himmer137 Ϫ7 n.s. Johnson149 Ϫ8 n.s. Rotbøll Nielsen203 Mean FRC ؊8 ؊27 OC: open cholecystectomy; LC: laparoscopic cholecystectomy; FVC: forced vital capacity; FEV1: one second volume; TLC: total lung capacity; MVV: maximal voluntary ventilation; FEFmax: maximal expiratory ﬂow; FEF25–75: maximal ﬂow between 25% und 75% of expiration; n.s.: not studied. *FRC was also reduced to a signiﬁcantly greater degree in the open cholecystectomy group at 6 and also at 72 h after surgery (see also Figure 2.13). Litres 7 Age Ͻ50 Age Ͻ50 6 FVC FEV1 Age Ͼ50 Age Ͼ50 4 4 5 3 FRC 3 4 Litres Litres 2 2 3 1 1 2 1 0 0 Preoperative 1 6 24 Baseline Day 1 Day 2 Day 3 Hours after surgery Figure 2.13 FRC is changed only slightly following laparo-Figure 2.12 Changes of FRC as a function of age. Recovery scopic cholecystectomy (Hamo and Crozier, unpublishedof FRC after laparoscopic cholecystectomy is slower in older data). The contrasts with the marked FRC reduction seenpatients. (Adapted from Ref .) after the open procedure (see Table 2.8).
PHYSIOLOGY 23 100 OC pressure from normal values to over 60 mmHg, and * LC this increase can persist even after IAP has been 80 released.154 Symptoms of increased intracranial pres- sure, such as headache and nausea, are seen signiﬁ-Incidence (%) * 60 * cantly more often after laparoscopic surgery than after open procedures.155 The cause of the ICP increase is thought to be venous congestion and increased pres- 40 * sure in the sagittal sinus, lumbar cistern and the dural sleeves of spinal nerve roots leading to impaired 20 cerebrospinal ﬂuid absorption.11,156 A mechanical abdominal wall retractor could be an alternative to 0 pneumoperitoneum in patients at risk of ICP None Micro Focal Segment Lobe increases, since animal studies have shown that ICP Extent of atelectasis does not increase during laparoscopy when a gaslessFigure 2.14 The incidence of pulmonary atelectasis abdominal wall lift device is employed.157,158detectable in chest radiogram is signiﬁcantly lower afterlaparoscopic (LC) than after open cholecystectomy (OC).This ﬁnding is relevant for the incidence of postoperative Neuroendocrine andpneumonia. (Adapted from Ref  and .) immunological reactions to laparoscopic surgerythe main causes of postoperative morbidity and mor- The rapid adoption of laparoscopic techniques hastality along with anastomotic leak and sepsis. All avail- made the prospective, randomized comparison ofable data suggest that the incidence of pulmonary laparoscopic operations with their conventional coun-complications is greatly reduced after laparoscopic terparts almost no longer possible. One would expectcholecystectomy and also suggest an advantage of the that the small incisions of laparoscopic surgery wouldlaparoscopic over the open approach for patients with induce only minor increases in the circulating con-pre-existing pulmonary pathology. The probability of centrations of the typical stress indicators, such asan uneventful postoperative course usually outweighs epinephrine, norepinephrine, cortisol and blood glu-the intraoperative problems. cose or the neuroendocrine hormones, such as vaso- pressin, adrenocorticotropin (ACTH) and prolactin. Note The results of the available comparative studies reveal a certain discordance in the reactions of the various • Postoperative impairment of pulmonary function neuroendocrine stress parameters. But expectation is signiﬁcantly less after laparoscopy than after laparotomy and reality do not coincide – numerous studies have • Arterial O2 desaturation is less severe after laparo- shown that perioperative endocrine stress responses scopic operations to laparoscopic surgery does not differ relevantly • The incidence of atelectases and pneumonia is lower from conventional open surgery laparoscopy.135,159–163 after laparoscopic operations Simply inﬂating the abdomen increases circulating plasma concentrations of catecholamines, ACTH, cor- tisol and vasopressin.164–166 Increasing IAP and CO2Intracranial pressure during absorption activates the sympathetic nervous systemlaparoscopy and stimulates the secretion of catecholamines from the adrenal medulla.167,168 The reduction of renalThe safety of laparoscopic surgery in patients with perfusion stimulates the release of renin from theelevated intracranial pressure (ICP) or closed head kidneys.169 Cortisol, ACTH, ␤-endorphin, interleukin-injuries is controversial. Pneumoperitoneum has 6, and blood glucose increase during surgery (Figurebeen shown in numerous animal studies to increase 2.15) while the plasma concentrations of insulin andICP, independent of arterial CO2 tension.11,151,152 glucagon remain unchanged.161,162,165, 170–172 Our dataStudies in children with ventriculoperitoneal shunts conﬁrm these ﬁndings. In a study comparing the timedemonstrated that inﬂating the abdomen immediately course of hormone concentrations during abdominalincreased intraventricular pressure by up to hysterectomy and laparoscopic cholecystectomy, we25 mmHg.153 When performed in patients with closed observed comparable increases of cortisol, epineph-head injuries, laparoscopy can increase intracranial rine and norepinephrine that indicate a similar degree
24 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY pg mlϪ1 g dlϪ1200 * 30 * *160 Vasopressin * 25 Renin * 20120 Cortisol 15 80 * * 10 * * 40 * 5 0 0 pg mlϪ1600 * 600 Epinephrine * *500 500 Norepinephrine * *400 400300 300 * *200 * 200 Figure 2.15 Intraoperative100 100 changes of cortisol, vasopressin and catecholamine plasma con- 0 0 centrations with laparoscopic Before After 10° 5 15 30 End cholecystectomy. (*P Ͻ 0.05 com- Induction Head-up Pneumoperitoneum (min) pared to baseline; Adapted from tilt Ref .) Laparoscopic cholecystectomy Norepinephrine (pg mlϪ1) 1000 600 Hysterectomy Epinephrine (pg mlϪ1) 800 500 400 600 Norepinephrine 300 400 200 Epinephrine 200 100 0 0 Induction Incision Intra End 0.5 1 2 4 operative Hours after surgery 200 Cholecystectomy 50 Hysterectomy Interleukin-6 (pg mlϪ1) 40 Cortisol (g dlϪ1) 150 30 100 Cortisol IL-6 20 50 10 0 0 Induction Incision Intra End 0.5 1 2 4 operative Hours after surgeryFigure 2.16 Perioperative changes of typical endocrine and inﬂammatory stress parameters interleukin-6 plasma concen-trations seen with laparoscopic cholecystectomy compared to a conventional abdominal operation of medium invasiveness(hysterectomy) (Crozier et al., unpublished data).
PHYSIOLOGY 25of intraoperative stress. However, the concentrations the same with laparoscopic or open cholecystec-of these hormones decreased postoperatively more tomy.135,169,170 In some studies, catecholamine res-rapidly after the laparoscopic operation (Figure 2.16). ponses were even more pronounced after laparoscopicPlasma concentrations of atrial natriuretic hormone operations.165 The temporal coincidence suggests aremained unchanged despite increased PCWP.173 causal relationship between the rapid increase ofThe perioperative time courses of catecholamines, plasma renin activity and vasopressin and norepineph-cortisol, vasopressin and blood glucose are virtually rine plasma concentrations and the concomitant blood pressure increase. A positive correlation between vaso- pressin concentrations and MAP was documented in one study.174 However, in other studies comparing OC OC 140 900 pneumoperitoneum with gasless mechanical wall lift, LC LC the increase in vasopressin plasma concentrations were 120 800 virtually identical in both groups, but MAP was signi- 700 Cortisol (nmol lϪ1) ﬁcantly lower in the wall lift group.64,169 Pneumoperi-IL-6 (pg mlϪ1) 100 Cortisol 600 toneum is considered a possible independent stimulus 80 500 for catecholamine secretion during surgery for the 60 400 resection of phaeochromocytoma.175 300 Open and laparoscopic operations do differ in the 40 ∗ 200 behaviour of indicators of tissue trauma, such as 20 ∗ 100 ∗ C-reactive protein, erythrocyte sedimentation rate 0 0 and leucocytes: changes of these parameters are Pre operative Hours Day 1 Day 2 postoperative attenuated following laparoscopic surgery.135,159–161,163 This might be due to the lower plasma concentrations Measuring times of interleukin-6 following minimally invasive opera-Figure 2.17 The less traumatic nature of laparoscopic sur- tions (Figure 2.17 and Table 2.9).135,163 The signiﬁ-gery compared to the conventional procedure is reﬂected cance of interleukin-6 as a stress parameter is seen inin the reduced increases of interleukin-6 (IL-6) (*P Ͻ 0.05 its pivotal importance in the acute phase reaction andfrom baseline). Cortisol concentrations are essentially the postoperative catabolism. The more rapid reconvales-same after both techniques. cence after laparoscopic surgery is likely to be due Table 2.9 Synopsis of the endocrine, metabolic and immunological reactions to the stress of open or laparoscopic cholecystectomy Parameter Donald Mealy Joris Mansour Rademaker Dionigi et al.165 et al.162 et al.135,171 et al.172 et al.170 et al.161 Epinephrine OϭL – (O ϭ L)* – – – Norepinephrine LϾO – (O ϭ L)* – – – VMA – LϾO – – – – Cortisol (O ϭ L)† OϭL OϭL OϭL OϭL OϾL ACTH OϾL – – – – – Prolactin – – – – – OϾL Vasopressin OϾL – – – – – Insulin – – – OϭL – – Glucagon – – – OϭL – – Blood glucose – – – OϭL OϭL – IL-6 – – OϾL – – – CRP – OϾL OϾL – – OϾL Leukocyte count – – OϾL – – – CD3-decrease – – – – – OϾL OKDR-decrease – – – – – OϾL O: open cholecystectomy; L: laparoscopic cholecystectomy; VMA: Vanillin mandelic acid; CRP: C-reactive protein; CD3-lympocyte count: total number of circulating T-lymphocytes; OKDR-count: number of activated lymphocytes in peripheral blood. *The ﬁrst blood sample 4 h postoperatively may have been too late to detect intraoperative changes. †Cortisol concentrations were similar in both groups, but returned to normal more rapidly in the laparoscopy group.
26 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYto the lower intensity of acute phase reactions that model when the operation was performed as openpersist into the postoperative period. laparotomy or laparoscopically with a room air pneu- moperitoneum than when He or CO2 were used toOne can only speculate on the reason for the lack of inﬂate the abdomen.182any spectacular difference in the classic endocrinestress reactions between minimally invasive operationsand their conventional counterparts. One might Notehypothesize that the adrenergic and adrenocortical • Laparoscopic surgery induces a marked endocrinereactions have a threshold that is lower than the stimu- stress reactionlus arising from IAP increase or manipulations on the • The reduction of tissue trauma with laparoscopicliver hilus. The afferent limb of the reﬂex loop might operations is reﬂected in a reduction of the inﬂam-possibly run through the vagus or phrenic nerves, matory response as attenuated changes of C-reactivesince the initial increases in the blood concentrations protein, interleukin-6, leukocyte count, erythrocyteof cortisol and glucose are not blocked by thoracic sedimentation rate and total T-lymphocyte countepidural anaesthesia.170 There is evidence that ele- • Laparoscopy causes less immunosuppression than laparotomyvated IAP alone is responsible for part of theendocrine stress reaction, since the increase of bothplasma renin activity and norepinephrine plasma con-centrations is attenuated when a mechanical abdomi- Temperature lossnal wall lift is used to enlarge the abdominal cavityinstead of gas insufﬂation.169 During laparotomy, a drop in body temperature occurs regularly due to radiant and evaporative heatTransient immunosuppression is observed following a losses from the open abdomen in combination withwide variety of injuries and surgical operations, and its the anaesthetic-induced impairment of thermoregula-magnitude depends to a certain extent on the extent of tory mechanisms. Unintentional hypothermia shouldthe tissue trauma. Immunosuppression is particularly be avoided since it can cause postoperative myocardialimportant in tumour surgery, since it encourages ischaemia and angina183 as well as enhance postopera-tumour growth176 and enhance the risk of metastases. tive tumour growth.184 Hypothermia does not occur ifLaparoscopy has a smaller effect on immunological the patient is completely draped and the wound isparameter than laparotomy. This has been documented small as in eye or otorhinolaryngological surgery. Thein animal studies, in which the delayed type hypersen- situation is similar during laparoscopic surgery, andsitivity to various, intradermally injected antigens was yet unexpected, and occasionally signiﬁcant cooling isretained after laparoscopy, but diminished following observed in nearly a third of all patients.185,186 The rea-laparotomy.177,178 Total leukocyte count is higher in son for this is likely to be the gas ﬂow through thepatients following an open cholecystectomy, but the abdominal cavity. An argument in favour of this expla-total T-lymphocyte count (CD3 cells) and the activated- nation is the correlation of temperature drop and vol-lymphocyte count (OKDR cells) was signiﬁcantly ume of insufﬂated gas. Body temperature decreases byreduced.161,179 0.3°C/50 l of insufﬂated gas.186 The ultimate causativeDifferences of this sort might be responsible for the factor could be the heat required for the intra-abdominalresults of an animal study in which tumour cells were evaporation of water to moisten the gas, or that requiredinoculated intradermally into mice subsequently sub- to bring the room temperature gas to body temperature.jected to either midline laparotomy or to abdominal The results of one study suggest that warming theinﬂation.180 Tumour were established more easily and insufﬂation gas to 30°C will prevent intraoperativegrew more aggressively in the laparotomy group. hypothermia during laparoscopy,187 although this isSeventy per cent of these animals, but none of those contradicted by a different study.188 Let us perform ain the laparoscopy group had intradermal tumours on simple calculation to assess the probability of thisday 14. There might also be a connection between the being correct.choice of insufﬂation gas, the degree of immunosup- The amount of heat required to bring the insufﬂatedpression and tumour growth. Animals studies have gas to body temperature can be calculated approxi-shown that abdominal insufﬂation with air or laparo- mately with Equation (2.3):tomy inhibits phagocytosis of Candida albicans cellsby peritoneal macrophages to a greater degree than CPCO (37 Ϫ gas temperature in °C)Vinsuffwhen CO2 is used for inﬂation.181 Recurrence of ⌬Q ϭ 2 MViexperimentally induced hepatocellular carcinoma wasmore frequent after partial hepatectomy in a murine (2.3)
PHYSIOLOGY 27where ⌬Q is the heat loss of the body in calories; ReferencesCPCO 2 is the molar heat capacity of CO2 under con-stant pressure at room temperature and is equal to 1. Joris JL, Noirot DP, Legrand MJ, Jacquet NJ,8.97 cal/°C and mole CO2; Vinsuff is the volume of Lamy ML. Hemodynamic changes during laparoscopicinsufﬂated gas in litres and MVi is the mole volume of cholecystectomy. Anesth Analg 1993; 76: 1067–1071.an ideal gas at 293ЊK (ϳ24.0 l). 2. Galizia G, Prizio G, Lieto E et al. Hemodynamic and pulmonary changes during open, carbon dioxideThe resulting temperature decrease ⌬T is a function pneumoperitoneum and abdominal wall-lifting chole-of the heat capacity and the mass of the body cystectomy. A prospective, randomized study. Surg Endosc 2001; 15: 477–483.(Equation (2.4)). The heat capacity is approximately 3. Lindgren L, Koivusalo A-M, Kellokumpu I.0.83 kcal/°C and kg: Conventional pneumoperitoneum compared with abdominal wall lift for laparoscopic cholecystectomy. ⌬Q (kcal)/0.83 (kcal°CϪ1 kgϪ1 ) Br J Anaesth 1995; 75: 567–572. ⌬T ϭ (2.4) 4. Andersson L, Lindberg G, Bringman S, Ramel S, body mass (kg) Anderberg B, Odeberg Wernerman S. Pneumo- peritoneum versus abdominal wall lift: effects on cen-With an initial gas temperature of 20°C, an insuf- tral haemodynamics and intrathoracic pressure duringﬂated gas volume of 50 l and a body mass of 75 kg, laparoscopic cholecystectomy. Acta Anaesthesiol Scandthe calculated heat loss would be 318 cal which 2003; 47: 838–846.would cause the body temperature to decrease by 5. Reid CW, Martineau RJ, Hull KA, Miller DR.0.005°C. Haemodynamic consequences of abdominal insufﬂa- tion with CO2 during laparoscopic cholecystectomy.This temperature change is far from the observed Can J Anaesth 1992; 39: A132.value of approximately Ϫ0.3°C/50 l.186 Even if the gas 6. Cunningham AJ, Turner J, Rosenbaum S, Rafferty T. Transoesophageal echocardiographic assessment ofleft the trocar under pressure and cooled adiabatically haemodynamic function during laparoscopic cholecys-to Ϫ10°C, the temperature drop that this would tectomy. Br J Anaesth 1993; 70: 621–625.induce in the body would only be about 0.015°C. It is 7. Beebe DS, McNevin MP, Crain JM et al. Evidenceobvious that gas warming alone does not explain the of venous stasis after abdominal insufﬂation forobservations, and that other factors must be acting to laparoscopic cholecystectomy. Surg Gynecol Obstet 1993;cause the change in body temperature. 176: 443–447. 8. Millard JA, Hill BB, Cook PS, Fenoglio ME,Large amounts of heat can be lost through evaporation Stahlgren LH. Intermittent sequential pneumaticof water from the surface of abdominal organs, and the compression in prevention of venous stasis associatedcontinuous ﬂow of dry gas will augment this process. with pneumoperitoneum during laparoscopic chole-If this was the cause, then moistening the insufﬂation cystectomy. Arch Surg 1993; 128: 914–918.gas should prevent intraoperative hypothermia. This 9. Giebler RM, Behrends M, Steffens T, Walz MK,was shown to be the case in animal studies.189,190 The Peitgen K, Peters J. Intraperitoneal and retroperitoneal carbon dioxide insufﬂation evoke different effects oncontribution of humidiﬁed insufﬂation gas to intra- caval vein pressure gradients in humans: evidence foroperative normothermia in adequately draped and the Starling resistor concept of abdominal venousexternally warmed patients was found to be minimal return. Anesthesiology 2000; 92: 1568–1580.in one study.191 Humidifying the insufﬂation gas and 10. Wachsberg RH, Sebastiano LLS, Levine CD.applying external warming to the patient will prevent Narrowing of the upper abdominal inferior vena cavaunintentional intraoperative hypothermia during in patients with elevated intraabdominal pressure.laparoscopic surgery.192–194 Abdom Imaging 1998; 23: 99–102. 11. Rosenthal RJ, Friedman RL, Chidambaram A et al. Effects of hyperventilation and hypoventilation on PaCO2 and intracranial pressure during acute eleva- Note tions of intraabdominal pressure with CO2 peri- toneum: large animal observations. J Am Coll Surg • Monitoring body temperature is recommended, 1998; 187: 32–38. since signiﬁcant hypothermia can occur during laparoscopic surgery 12. Takata M, Wise RA, Robotham JL. Effects of abdominal pressure on venous return: abdominal vas- • Appropriate preventive measures such as humidify- cular zone conditions. J Appl Physiol 1990; 69: ing the insufﬂation gas, forced air heating or heat- ing blankets should be taken in patients with an 1961–1972. increased risk of cardiovascular complications or 13. Jorgensen JO, Lalak NJ, North L, Hanel K, Hunt DR, those undergoing laparoscopic tumour surgery Morris DL. Venous stasis during laparoscopic chole- cystectomy. Surg Laparosc Endosc 1994; 4: 128–133.
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PREPARING AND POSITIONING FOR LAPAROSCOPIC SURGERY 3The positioning of the patient for laparoscopic surgery, One arm is all one needs for venous access, but if bothand the positions of the surgeon, assistants and scrub arms are ﬁxed at the patient’s sides, one can eithernurses differ in many ways from conventional oper- connect an extension with an access port to a catheterations. These differences must be taken into account in a peripheral vein, or one can cannulate the externalwhen preparing the patient for anaesthesia, since they jugular vein, which usually remains fairly accessiblefrequently interfere with routine management and even when the patient is completely draped. In moreimpair the anaesthetist’s access to the patient’s head extensive operations, and especially with older patients,and extremities. A simple example in point is the pos- the use of a central venous catheter might be indicateditioning for a laparoscopic herniotomy. In the conven- in any case. Infusion lines from the syringe pumpstional procedure, the surgeon stands at the level of the for intravenous anaesthetics should be connected asgroin, and the anaesthetist has unimpeded access to closely as possible to the catheter to avoid infusionthe arms and head. For the laparoscopic procedure, dead-space.on the other hand, the surgeon stands at the patient’shead in order to guide the instruments from above, into When the patient’s head is covered with drapes,the hernial oriﬁce. One or even both of the patient’s particular care must be taken to protect the eyes fromarms are positioned at his side, his head is almost com- abrasions and other injuries. This is usually done bypletely covered and the operating table is brought into taping the eyelids shut with a strip of non-irritatinga steep Trendelenburg position. The result of this is surgical adhesive tape (e.g. Leukosilk®). This does notthat the anaesthetist has difﬁculties in accessing the always prevent corneal abrasions,5 but not taking thisvenous cannulae and the endotracheal tube, as well as kind of precaution might be construed as negligence.monitoring the patient’s skin colour and pupils. At the We do not use eye ointment in our institution, sincesame time, there is a higher risk of endotracheal tube the patients complain of postoperative visual impair-movement relative to the carina with endobronchial ment caused by corneal oedema or conjunctivitis. Ifintubation,1–4 without the anaesthetist being unable to there is any danger of the patient’s eyes being exposedconﬁrm or correct it (Figure 3.1). to pressure (e.g. members of the surgical team leaning on the patient’s head), plastic eye protectors can be applied (Figure 3.3).Preparing the patient The position of the endotracheal tube and thePreparing the patient for anaesthesia – from selecting presence of bilateral breath sounds must be conﬁrmedthe venous cannulation site, to the choice of endotra- by careful auscultation after intubation, and thencheal tube and the monitoring modes – must take the checked at regular intervals during the operation, sinceabove-mentioned set of problems and risks as well as the tube can migrate into an endobronchial position.1–4the particular routine of the individual hospital into A double-lumen endotracheal tube, usually a left-sidedaccount. For the anaesthetist, it is important to retain tube, is usually required for thoracoscopic operationsaccess to at least one of the patient’s arms and to to allow one-lung ventilation with collapse of the lungthe head and endotracheal tube. Unfortunately, this is on the affected side.not always possible, either because it would interferewith the operation, or simply because that is just the When the patient is in a steep head-down position,way things are done. In some hospitals, for example, padded shoulder supports must be used to preventthe video monitor for laparoscopic cholecystectomy him from slipping. These should not be attachedand other upper abdominal procedures is mounted either too far laterally or too far medially, so as toon a bridge that spans the patient’s head. Both of the avoid damage to the brachial plexus, a common com-patient’s arms are positioned at his side, and access to plication of the Trendelenburg position (see Chapter 6).his head in the event of an emergency is nearly impos- For the same reason, the patient should not be fas-sible impeded (Figure 3.2). tened by the wrists.6,7
36 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY (a) (b)Figure 3.1 Patient undergoing laparoscopic hernioplasty. (a) One recognizes the Trendelenburg position with the patient’shead completely covered and towards the left of the picture, and the inﬂated abdomen. (b) The patient as seen by theanaesthetist. One arm is positioned above the patient’s head to facilitate access to the venous cannula.It is not necessary to insert a urinary catheter for surgical access, and only three out of 50 patientscholecystectomy, or for any other upper abdom- require a single postoperative catheterization.inal procedure of short duration.8 Voiding the However, the situation is different with laparoscopicbladder before the operation ensures adequate hernia repair or other lower abdominal and pelvic
P R E PA R I N G A N D P O S I T I O N I N G F O R L A PA R O S C O P I C S U R G E RY 37 (a) (b)Figure 3.2 Monitor support bridge used for laparoscopic cholecystectomy and other upper abdominal procedures.(a) Surgeon’s view. (b) Anaesthetist’s view.operations. A distended bladder can impede surgical The indication for inserting a central venous cath-progress during these procedures, and can increase eter is based, ﬁrst of all, on the clinical status of thethe risk of injury to the bladder when inserting the patient, as well as on the invasiveness of the surgicaltrocars. procedure. An indwelling arterial catheter for invasive
38 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Positioning the patient The patient’s position for laparoscopic surgery depends on whether it is for an upper abdominal, a lower abdominal or a thoracic procedure. The patient is usually positioned so that gravity causes the abdominal organs to fall away from the operation site to facilitate surgical access. For most operations in the upper abdomen, for example cholecystectomy, or gastric or hepatic surgery, the patient is supine in a head-up position, with the surgeon looking in a caudal-to-cranial direction. For operations in the lower abdomen, such as hernioplasty, appendectomy, hysterectomy or colorectal surgery, the patient is in a head-down Trendelenburg position and tilted from side to side as necessary. For operations in the thorax, for example for oesophagus or lung surgery, the patient is placed in a lateral decubitus position, with the side to be operated on uppermost. The following describes the particular points for typical operations in more detail. Upper abdominal operations Cholecystectomy Since the gall bladder lies on the underside of the liver, the surgeon must approach it from a caudal position, standing at the patient’s lower end and looking towards his head. There are two differentFigure 3.3 Eye protectors to prevent mechanical damage schools with regard to where the surgeon stands. Theto the eyes or corneal abrasions. “French” school, also known as the “European” school,9 has the patient positioned supine with the legs slightly abducted and ﬂexed at the hip. The sur-blood pressure monitoring is indicated for patients geon stands between the legs and views the videowith increased cardiac risk. It can provide useful screen placed near the patient’s right shoulder or on ainformation for the management of patients with bridge over the patient’s head. This bridge, which issevere pulmonary impairment, and for coping with shown in Figure 3.2, makes access to the patient’sdifﬁcult respiratory situations (see Chapter 4). head very difﬁcult. The ﬁrst assistant stands to the right, while the second assistant and the scrub nurse stand to the left of the patient (Figure 3.4). Note The patient’s arms are often fastened at his sides for laparoscopic procedures: With the “American” method, the patient lies supine or in a slight head-up position, with legs together. The • Attach non-compliant extension lines to the venous surgeon stands to the left of the patient at about hip and arterial catheters level, while the ﬁrst assistant and the video monitor are • Consider catheterization of the jugular vein (external on the patient’s right. One arm can be abducted to 90 or internal) degrees, and the head remains freely accessible (Figure The head is often completely covered: 3.5). There are thus no particular problems associated • Protect the eyes from mechanical injury with this position with regard to the technical aspects • Secure endotracheal tube against dislocation of anaesthetic management. Some suggest that the • Check position of endotracheal tube frequently patient be positioned in a left lateral decubitus position for cholecystectomy,10 since this would facilitate intra- Consider urinary catheterization for lower abdominal operations. operative endoscopic retrograde cholangiopancreato- graphy (ERCP) should this become necessary.
P R E PA R I N G A N D P O S I T I O N I N G F O R L A PA R O S C O P I C S U R G E RY 39 A A e Monitor Video mount Drap In vid suffla eo t S3 rec or ord er tor ni Mo vid Ins reco S2 S3 S2 eo S1 uff lat rder or Mo S1 N nito N Instruments r Inst rum ents Figure 3.5 Positioning for laparoscopic cholecystectomy according to the American method. The video monitor forFigure 3.4 Positioning for laparoscopic cholecystectomy the surgeon is mounted to the patient right in this diagram.according to the European method. The anaesthetist is The assistants follow the operation on the monitor posi-marked in the diagram with an A, while S1 represents the tioned next to the surgeon.surgeon, S2 and S3 the surgical assistants, and N the scrubnurse. The video monitor is mounted on a bridge over thepatient’s head in this diagram. AGastric and hepatic surgeryFor gastric (e.g. fundoplication, ulcer surgery, vago-tomy, gastroplasty) or hepatic surgery, the patient isplaced in a position similar to that for cholecystec-tomy. Here, too, the surgeon stands either betweenthe patient’s legs or at his side at hip level (Figures 3.4 S1 S2and 3.5). Note Upper abdominal operations: In • Patient supine or in slight head up position, in some N vid suffla eo cases tilted slightly to the left rec tor ord er • One arm can be free, but both are often positioned alongside the patient Instruments Mon itorLower abdominal operationsInguinal hernioplastyInguinal hernia repair requires the surgeon toapproach the surgical site from the patient’s headlooking caudal towards the hernia. He stands abouteven with the patient’s shoulder on the side opposite Figure 3.6 Positions of the surgeon and the patient forthe hernia. Both of the patient’s arms are positioned inguinal hernia repair. The video monitor stands near theclose to his body so that the surgeon has maximal patient’s feet. Both arms are adducted and the patient’sfreedom of movement from all sides (Figure 3.6). head is draped.
40 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY (a) (b)Figure 3.7 Shoulder support designed by the German gynaecologist Semm, on which the surgeon can support his or herupper body when operating in the pelvis, lower abdomen or groin. The support protects the patient’s head and eyes frommechanical damage, but limits the anaesthetist’s access to the arms, the head and the endotracheal tube.This is highly inconvenient for the anaesthetist, since the patient’s body, but it can be positioned above thehe cannot access peripheral venous cannulae. If only patient’s head (Figure 3.1(b)). This position is particu-one side is to be operated on, the arm opposite larly useful if an arterial catheter is being used.the surgeon can usually be abducted. With bilateral Unfortunately, this position is not possible when ahernioplasty, it is not possible to abduct an arm from shoulder support, on which the surgeon can lean, is
P R E PA R I N G A N D P O S I T I O N I N G F O R L A PA R O S C O P I C S U R G E RY 41 A A rm er dia recor r to d y vid suffla S3 S3 the eo In video recorder Insufflator diathermy S1 S1 S2 Monitor N N r ito on M S2 nts Instru rume ment s InstFigure 3.8 Position of the patient and surgeons for append- Figure 3.9 For operations on sigmoid and descendingectomy and operations on the ascending colon. The colon the surgeon stands to the patient’s right with thepatient’s right arm can be abducted, allowing access to surgical assistants positioned across from him. Both of thevenous catheter. The head is easily accessible. The anaes- patient’s arms are adducted, making access to venousthetist is marked in the diagram with an A, while S1 repre- catheters difﬁcult. The head is freely accessible.sents the surgeon, S2 and S3 the surgical assistants, and Nthe scrub nurse. Surgeon and assistants follow the oper-ation on the video monitor mounted across the patientfrom their position. (LAVH), the patient is in the lithotomy position. The surgeon stands about level with the patient’s chest, one assistant stands next to him, and anotherinstalled (Figure 3.7). A further problem in the pos- stands between the patient’s legs. It depends onitioning for herniotomy is that the patient’s head is the surgeon as to whether the operation is to beoften completely draped, to prevent accidental con- carried out from one side only, or if he wants totamination of instruments and surgical personnel. A change sides during the procedure. One arm can bepatient in such a position requires an athletic anaes- abducted (usually the left) but sometimes both armsthetist (see Figure 3.1). have to be placed next to the patient’s body. The anaesthetist should ask beforehand in order to plan venous access.Appendectomy and colorectal surgeryFor appendectomy, as for most colorectal operations, The patient is routinely tilted head-down to allow thethe surgeon’s direction of sight is not nearly as paral- pelvic organs to fall free and facilitate surgical access.lel to the vertical axis of the patient’s body as with This is associated with a number of problems, fromhernia repair. The surgeon stands on the side of the securing the patient on the operating table, for provid-patient opposite the lesion (Figure 3.8). For oper- ing adequate ventilation and detecting if the endo-ations on the sigmoid and descending colon the sur- tracheal tube has migrated into an endobronchialgeon stands on the patient’s right side (Figure 3.9). position (vide supra). Urological surgeryGynaecological laparoscopic surgery The patient’s position for most urological surgery,For all gynaecological laparoscopic operations, for such as orchidopexy, varicoceles, cryptorchism, etc.,example sterilization, ovarian cysts, uterine myomas is similar to that for hernia repair (vide supra). Theor laparoscopically assisted vaginal hysterectomy head is draped, but one arm can be positioned over
42 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY (a) (b)Figure 3.10 Patient positioned in a mild jack-knife position for retroperitoneal laparoscopic adrenalectomy. The patient’shead is toward the left in (a) and the legs are lowered. The surgeon and his assistant stand on the same side of the patient asseen in (b).the patient’s head. During laparoscopic nephrectomy Note Lower abdominal surgery:or transperitoneal adrenalectomy, the patient is in thelateral decubitus position with the affected side up. • Patient is usually in a more or less steep, head-downRetroperitoneal adrenalectomy is performed with the positionpatient prone and the legs slightly lower than the dor- • Partial end-expiratory pressure (PEEP) ventilation is recommendedsal costal margin (Figure 3.10). Retroperitoneal lym-phadenectomy is performed with the patient in a • The tip of the endotracheal tube can migrate with resulting endobronchial intubationslight Trendelenburg position as for a prostatectomy.
P R E PA R I N G A N D P O S I T I O N I N G F O R L A PA R O S C O P I C S U R G E RY 43 A S1 r ito on M S2 N S2 Instruments S1 A NFigure 3.11 Positioning the patient for thoracoscopic sur-gery. The patient is in a lateral decubitus position with thesurgeon standing in front of his chest. The anaesthetist is Figure 3.12 Approach to the patient for mediastinalmarked in the diagram with an A, while S1 represents the procedures.surgeon, S2 the surgical assistants, and N the scrub nurse. by only about 30 degrees to the contralateral side.Thoracoscopic surgery The contralateral arm is either abducted or pos- itioned alongside the patient, while the ipsilateral armOperations on the oesophagus and lungs is brought over the patient’s head and is accessible forThoracoscopic surgery is usually performed with the the anaesthetist.patient in a lateral decubitus position. For surgery ofthe thoracic section of the oesophagus or the right Mediastinal surgerylung, the patient is positioned on his left side. Thesurgeon stands facing the patient’s chest but slightly The patient is supine in a slight head-up position, andcaudal of the trocar insertion site looking cephalad the surgeon approaches him from cephalad. The(Figure 3.11). The lower arm stretches away from the patient’s head is draped, but at least one arm ispatient’s body, while the upper arm is bent at the usually accessible (Figure 3.12).elbow and brought over the patient’s head. Selectiveventilation with a double-lumen endotracheal tube isrecommended, so that ventilation can be interrupted Note Thoracoscopic operations:on the side being operated on. An indwelling arterial • Patient usually in lateral decubitus position (excep-catheter is useful for monitoring arterial oxygen tions: sympathectomy, coronary artery surgery)tensions and the magnitude of pulmonary shunt • Use double-lumen endotracheal tubeperfusion. For more details see Chapter 9.Thoracoscopic sympathectomy ReferencesFor this operation, the patient is positioned as for 1. Mendonca C, Baguley I, Kuipers AJ, King D, Lam FY.other intrathoracic procedures, except that he is tilted Movement of the endotracheal tube during laparoscopic
44 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY hernia repair. Acta Anaesthesiol Scand 2000; 44: 6. Mitterschiffthaler G, Theiner A, Posch G, Jäger- 517–519. Lackner E, Fuith LC. Läsion des Plexus brachialis, 2. Lobato EB, Paige GB, Brown MM, Bennett B, verursacht durch fehlerhafte Operationslagerungen Davis JD. Pneumoperitoneum as a risk factor for endo- [Lesion of the brachial plexus, caused by wrong pos- bronchial intubation during laparoscopic gynecologic itioning during surgery]. Anasth Intensivther Notfallmed surgery. Anesth Analg 1998; 86: 301–303. 1987; 22: 177–180.3. Morimura N, Inoue K, Miwa T. Chest roentgenogram 7. Romanowski L, Reich H, McGlynn F, Adelson MD, demonstrates cephalad movement of the carina during Taylor PJ. Brachial plexus neuropathies after advanced laparoscopic cholecystectomy. Anesthesiology 1994; 81: laparoscopic surgery. Fertil Steril 1993; 60: 729–732. 1301–1302. 8. Mowschenson PM, Weinstein ME. Why catheterize4. Hamm P, Lang C, Fornecker ML, Bruant P, Vuillemin F. the bladder for laparoscopic cholecystectomy? J Intubation bronchique séléctive à répétition au cours Laparoendosc Surg 1992; 2: 215–217. d’une cholécystectomie coelioscopique [Recurrent 9. Perissat J. Laparoscopic cholecystectomy: the European selective bronchial intubation in laparoscopic chole- experience. Am J Surg 1993; 165: 444–449. cystectomy]. Ann Fr Anesth Reanim 1993; 12: 67–69. 10. Grieve DA, Merrett ND, Matthews AR, Wilson R.5. Bronheim D, Abel M, Neustein S. Corneal abrasions Left lateral laparoscopic cholecystectomy and its rele- following non-ophthalmic surgery: A retrospective vance to choledocholithiasis. Aust NZ J Surg 1993; 63: review of 35,253 general anesthetics. Anesthesiology 715–718. 1995; 83(Suppl): A1071.
MONITORING 4Monitoring for minimally invasive operations is essen- patient’s skin colour even more difﬁcult. Pulse oxime-tially the same as for the conventional counterparts try measures pulsatile changes of light absorption atwith basic monitoring of circulatory and respiratory two wavelengths to calculate the percentage of oxy-parameters as well as surveillance of the correct func- haemoglobin in the blood.3 The method can delivertioning of the auxiliary support apparatus, such as false readings if other haemoglobins, for example car-ventilators, drug infusion equipment, etc. However, boxyhaemoglobin (COHb) and methaemoglobin, arelaparoscopic surgery forces a shift of emphasis to par- present in appreciable concentrations. COHb, whichticular aspects of the monitoring spectrum, and man- gives false high readings,4 is frequently increased indates the inclusion of some parameters that might not smokers, since they can still have COHb concentra-be so crucial for the conventional procedures. Carbon tions above 5%, hours after the last smoke inhalation.dioxide (CO2) absorption and alterations of pulmonary Carbon monoxide is also produced in the abdomen byfunction are the two characteristic features that come electrocautery and the use of lasers and is absorbedto mind. The primary aim of monitoring is, of course, from there into the blood.5–7 Methaemoglobinaemia,to ensure the maximum safety for the patient, but in which causes either incorrectly high or low readings,8minimally invasive surgery there is an additional goal is less likely to be a problem during laparoscopic sur-of helping to exploit the concept to its fullest extent. gery, since mentionable amounts usually only appear after inﬁltration with large amounts of prilocaine, or during infusions of nitroglycerine or sodium nitro-Respiratory monitoring prusside in patients with methaemoglobin reductase deﬁciency. Methylene blue, which is occasionallyMonitoring of oxygenation and ventilation is especially injected to visualize renal function and ureter patency,important during laparoscopic surgery, because, on the can be an iatrogenic source of incorrect pulse oximetryone hand, these functions are directly impaired by the readings and give false low SpO2 values.9operations themselves, and are additionally challenged A treacherous cause of arterial O2 desaturation is theby the uptake of CO2 on the other. Peripheral pulse intraoperative migration of the endotracheal tubeoximetry and capnometry are usually adequate surro- into an endobronchial position. This is not infrequentgate measures of arterial oxygen (O2) and CO2 ten- during laparoscopic surgery and is facilitated by thesions, although under some circumstances capnometry relative shift of the carina due to the head-down pos-may be misleading (see below). ition and the additional force of the pneumoperi- toneum,10–14 although it can also occur in the reverseOxygenation Trendelenburg position as well.15 Table 4.1 summar- izes typical causes of intraoperative arterial O2 desat-Pneumoperitoneum and the head-down tilt tend to uration and their treatment.intensify the occurrence of atelectatic regions in thelung1 that appear after induction of anaesthesia in the Ventilationsupine patient, and to further increase venous admix-ture, widening the alveolar–arterial O2 difference The deﬁning factor in most laparoscopic operations is(AaDO2) and increasing the risk of hypoxaemia dur- the creation of the CO2 pneumoperitoneum. It wasing laparoscopic procedures. Clinical monitoring of recognized early on that arterial CO2 tension increasesthe patient’s skin colour is not sufﬁcient, since arterial if the absorbed CO2 is not eliminated by increasingO2 desaturation can occur in patients with apparently alveolar ventilation.16 Years of experience and count-adequate ventilatory parameters and with no signs of less studies have shown that the degree of CO2cyanosis. In one study, 16 of 108 patients had arterial adsorption is unpredictable, and it is impossible toO2 saturation below 90% without visible cyanosis.2 In calculate beforehand by exactly which amount venti-addition, the operating theatre is usually darkened latory minute volume will have to be increased,17–19during laparoscopic surgery, which makes judging the although attempts in this direction have been made.20
46 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Table 4.1 Causes of arterial O2 desaturation detected by pulse oximetry Cause Remarks Therapy Increased venous admixture Most common cause Adapt ventilation (e.g. atelectasis) (recruitment, PEEP) Endobronchial intubation Auscultate Retract endotracheal tube Bronchial secretions Auscultate Remove by suctioning Impaired pulmonary perfusion For example embolism Speciﬁc therapy Poor peripheral perfusion Blood gases to conﬁrm Treat circulation, active (centralization, hypothermia, (PaO2, pH, lactate) warming shock, hypovolaemia) FIO2 too low Rarely sole cause Increase FIO2 Ventilator disconnected Frequent cause Reconnect to patient COHb, Met-Hb Rare causes Met-Hb: methaemoglobin; PEEP: positive end-expiratory pressure.Hypercapnia and hypocapnia, with their accompanying The ventilation–perfusion ratio changes, for example,disturbances of the acid–base status can only be avoided when pulmonary perfusion is shifted by a fall in bloodby monitoring partial pressure of CO2 in arterial blood pressure. Ventilatory distribution changes as a result(PaCO2) and adjusting ventilation as necessary. Several of increased intra-abdominal pressure or an extrememonitoring methods are available, each with its advan- head-down position. The head-up position convertstages and disadvantages. An understanding of the apical lung segments to West I zones22 and increasesshortcomings of each method, and how it might be alveolar dead-space ventilation (VD/VT). In all ofaffected by the changes during laparoscopic surgery is these cases, PetCO2 deviates from the actual PaCO2 tonecessary in order to use each to its fullest advantage. an increasing degree, as illustrated in Figure 4.1.23,24 This deviation is greatest in older patients, especiallyCapnometry in those with pre-existing lung disease. Due to the problems mentioned above, capnometry may giveCapnometry, or measuring the concentration of CO2 in incorrect results during prolonged operations, espe-the expired air, is the easiest, non-invasive method of cially in patients with pre-existing pulmonary disease,monitoring ventilation. It is based on the assumption and it should supplemented with other methods (seethat the end-tidal CO2 partial pressure (PetCO2) is the below).same as the CO2 partial pressure in the alveolar gasmixture (PACO2), and that this in turn approximates When evaluating the changes in PetCO2, the followingthe PaCO2. The usefulness of PetCO2 for monitoring factors should be taken into account: an increase inassumes further that alveolar dead space, and hence PetCO2 is almost always due to an increase in PaCO2,the difference between PaCO2 and PetCO2 (PaCO2 Ϫ which can be caused by hypoventilation, for example,PetCO2), remains constant during the observation or a rise in body temperature; increased muscle activ-period. This assumption is not consistently valid during ity; increased CO2 adsorption or malignant hyper-anaesthesia and ventilation, since the ventilation– pyrexia. However, a rapid rise in PetCO2, without aperfusion ratio changes intraoperatively, with a shift in concomitant change in PaCO2, is routinely observedthe distribution of the alveoli that are hypoventilated when pulmonary perfusion improves; for example,or hyperventilated relative to their perfusion. The when blood pressure increases in response to surgicalhypoventilated areas have no effect on capnometry. The stimulation. The reason for this is the reduction inair in the hyperventilated alveoli, however, has a CO2 the extent of West I areas in the lungs, which reducestension lower than that in arterial blood. The air from alveolar VD/VT. A decrease in PetCO2 can indicatethis alveolar dead space “dilutes” the air from the nor- hyperventilation. But it can also be caused by a reduc-mally ventilated areas, resulting in a PetCO2 that is tion of CO2 production by the body (anaesthesialower than the PaCO2.21 During normal surgery, this effect), or by an increase in alveolar VD/VT as a resultdifference is usually of no consequence, but it acquires of regional (e.g. pulmonary embolism, head-up pos-clinical relevance in laparoscopic operations. ition) or global (e.g. blood pressure decrease) reduction
MONITORING 47 Pulmonary artery pressure level A B C Embolus D E Figure 4.1 Numerous factors inﬂuence the reliability of capnometry. Perfusion of the alveoli A, C, D and E is reduced, Pre-capillary vasoconstriction and the ventilation– perfusion ratio is increased above unity. The result is VD/VT with a reduction in PetCO2. be useful in adults as well.25–27 The validity of the Table 4.2 Interpreting capnometry data method rests on two observations, ﬁrst of all, that the Cause Clinical consequence CO2 tension of capillary blood in hyperaemic skin is virtually identical to that of the arterial blood, and PetCO2 increase secondly, that CO2 diffuses rapidly from the capillar- Hypoventilation Increase ventilation ies through the epidermis. Increased CO2 absorption Increase ventilation, check for intravasal insufﬂation In this method, the skin is made hyperaemic by Decrease in VD/VT Observe, and adjust actively heating it to 44°C, and CO2 is measured in ventilation, if necessary the skin under the heating electrode. Uncorrected Malignant hyperpyrexia Speciﬁc therapy transcutaneous CO2 (PtcCO2) is higher than capillary PetCO2 decrease CO2 due to the contribution of CO2 from cutaneous Hyperventilation Reduce ventilation metabolism. A factor is entered manually to correct Gas embolism Speciﬁc therapy (see for this (Figure 4.3). Reduced cutaneous perfusion Chapter 6) will produce false high values, because the CO2 from Reduced CO2 production Adapt ventilation, if cutaneous metabolism will accumulate.28 (effect of anaesthesia) necessary Increased VD/VT Observe, and adjust In a study in patients undergoing laparoscopic (positioning, reduced ventilation, if necessary herniotomy and cholecystectomy, we observed a con- pulmonary perfusion, etc.) stant difference between measured PaCO2 and PtcCO2 (PaCO2 Ϫ PtcCO2), while PaCO2 Ϫ PetCO2 tensions increased during the course of the operations (Figureof lung perfusion (Figure 4.1). If one suspects that the 4.2). Moreover, we found a poor correlation betweencapnometry data might be incorrect, blood gases should PetCO2 and the PaCO2, which worsened during thebe measured frequently to clarify the situation. Venous operation (Figure 4.3). The correlation betweenblood samples are adequate for assessing PCO2. Table PaCO2 and PtcCO2 on the other hand was acceptable4.2 summarizes the approach to capnometric data. (Figure 4.4). This observation has also been conﬁrmed by others.24Transcutaneous CO2 monitoring Transcutaneous CO2 measurement is a useful supple-Measuring capillary PaCO2 through the intact skin is ment to capnometry for monitoring the efﬁciency ofanother non-invasive way to monitor ventilation that ventilation in patients with pulmonary disease. However,is widely used in neonatology and has been shown to it should not replace capnometry completely, since only
48 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY 0 65 Beginning of surgery Ϫ1 End of surgery 60 Ϫ2 Line of identityPetCO2 Ϫ PaCO2 (mmHg) Ϫ3 PtcCO2 (mmHg) Baseline 55 End Ϫ4 50 (r ϭ 0.74) Ϫ5 Begin 45 Ϫ6 (r ϭ 0.58) Ϫ7 40 During Ϫ8 35 pneumoperitoneum Ϫ9 30 Ϫ10 25 30 35 40 45 50 55 60 Ϫ11 PaCO2 (mmHg) Ϫ12 Figure 4.4 PtcCO2 and PaCO2 correlate well at the start of Ϫ13 Ϫ5 Ϫ4 Ϫ3 Ϫ2 Ϫ1 0 1 2 3 4 5 6 7 8 surgery, and the correlation improves during laparoscopic PtcCO2 Ϫ PaCO2 (mmHg) cholecystectomy.Figure 4.2 The PetCO2 Ϫ PaCO2 increases during thecourse of laparoscopic herniotomy, while PtcCO2 Ϫ PaCO2remain constant during the same period. Table 4.3 Recommendations for monitoring ventilation during laparoscopic surgery Operation Patient status Recommended Beginning of surgery monitoring End of surgery 55 Short (Ͻ2 h) Young, healthy Capnometry Line of identity lungs 50 PetCO2 (mmHg) Ͼ60 years Capnometry, 45 Begin occasional (r ϭ 0.35) venous BGA 40 Pulmonary Capnometry, 35 End disease repeated BGA or (r ϭ 0.16) (e.g. COLD) transcutaneous CO2 30 measurement 25 Long All patients Capnometry, (Ͼ2 hours) repeated BGA, 20 PtcCO2 25 30 35 40 45 50 55 60 PaCO2 (mmHg) Extraperitoneal, All patients Capnometry, retroperitoneal repeated BGA,Figure 4.3 The correlation between capnometric and PtcCO2PaCO2 is poor at the start of surgery and worsens during BGA: blood gas analysis; COLD: chronic obstructive lung disease.laparoscopic cholecystectomy.capnometry detects rapid changes of end-tidal CO2, blood pressure measurement provide sufﬁcient infor-which might reﬂect ventilator disconnection, airway mation; central venous pressure (CVP) monitoring orobstruction or pulmonary embolism, changes that are arterial cannulation is unnecessary. In patients withnot detected by transcutaneous CO2 monitoring.29,30 ischaemic heart disease, automated ST segment analy-Table 4.3 summarizes the recommended monitoring of sis of the ECG provides early warning of myocardialventilation during laparoscopic surgery. ischaemia, which can occur frequently during laparo- scopic surgery (see Chapter 2).Haemodynamic monitoring However, minimally invasive surgery is frequentlyIn healthy patients and laparoscopic operations with indicated in patients with co-morbidity so severelittle risk of circulatory complications, a standard that conventional procedures are contraindicated.5-lead electrocardiogram (ECG) and non-invasive Laparoscopic cholecystectomy is a typical example.
MONITORING 49These patients will, of course, require much more Doppler CO measurement compared to thermodilu-invasive monitoring, up to and including cardiac out- tion from Ϫ0.89 l minϪ1 to ϩ0.55 l minϪ1. The limitsput (CO) or ventricular regional wall motion monitor- of agreement with thermodilution that were initiallying. For such patients, continuous invasive arterial between Ϫ2.67 and ϩ0.88 l minϪ1, deteriorated afterpressure monitoring contributes substantially to the blood ﬂow redistribution to between Ϫ3.21 andsafety of anaesthetic management, and will facilitate ϩ4.30 l minϪ1, which is inacceptable.39 The increaseserial blood gas monitoring to assess pulmonary func- in peripheral vascular resistance caused by creatingtion and perfusion. CVP monitoring might be useful the pneumoperitoneum is likely to cause a redistribu-in these patients, if one keeps in mind the problems tion of blood ﬂow as will placing the patient in a steepassociated with interpreting CVP changes during Trendelenburg or reverse Trendelenburg position.pneumoperitoneum as described in Chapter 2. If the Another factor that might contribute to the high vari-patient’s condition warrants close control of atrial ﬁll- ability of oesophageal Doppler CO monitoring is theing pressures, a pulmonary artery catheter or trans- fact that it does not include blood ﬂow to the coronar-oesophageal echocardiography (TEE) might be ies, the upper extremities and the brain. This errorindicated. Patients with impaired ventricular function, cannot be corrected for with a constant factor, sincebut undergoing operations that are known to increase blood ﬂow to the coronary arteries and the brain arethe cardiac workload by increasing the vascular after- subject to ﬂuctuations which themselves are functionsload, should have CO, left ventricular ﬁlling pressure of anaesthesia and surgical stimulation, and do notand systemic vascular resistance monitored to gain the always represent the same fraction of CO. Forinformation required for optimal control ﬂuid example, the typical intraoperative rise in PaCO2 willreplacement, and inotrope and vasodilator therapy. trigger an absolute as well as percentage-wise increaseWith a pulmonary artery catheter, one can measure in cerebral blood ﬂow.CO and also right and left ventricular ﬁlling pressures.This is a standard method, but it is complicated and Bioimpedance is another well-known, non-invasiveassociated with serious complications, and should only method for determining CO that is suitable for con-be employed if strictly indicated. There are a variety of tinuous monitoring, and which has already been usednon-invasive method for measuring CO which can in studies involving laparoscopic operations.40,41 Withprovide useful information if their particular limita- this method, changes in transthoracic impedance aretions and defects are borne in mind. Among these are analysed against a high-frequency current. The strokeDoppler sonography and bioimpedance, both of volume is calculated from the distance between elec-which can be used for CO measurements, but do not trodes on the upper and lower thorax aperture, theallow the measurement of pulmonary artery or left temporal change in impedance, the baseline impend-ventricular ﬁlling pressures.31 ence and the time. But the distance between the upper and lower electrodes, the constancy of which isDoppler methods measure the velocity of blood ﬂow- most critical, is altered by the creation of the peri-ing in the aorta, from which CO is calculated incorp- toneum and longitudinal data over time are difﬁcultorating the aortic cross section (predicted or to interpret (see Chapter 2). The bioimpedance tech-measured), heart rate and ejection time. Earlier nique is also of no use during thoracoscopy, becausemethods used a transcutaneous approach from the the changes in baseline impedance caused by creatingsuprasternal notch, which yielded a satisfactory cor- a pneumothorax are not calculable. Comparativerelation with the results obtained by thermodilu- studies show an acceptable total correlation of COtion.32,33 This is not feasible during most laparoscopic data measured by bioimpedance with those derivedoperations. Using an oesophageal probe will avoid the from thermodilution, but the values of the individualproblems of access associated with laparoscopic sur- measurements varied widely (Ϯ1.5 l minϪ1) andgery. The initial results were very poor and the corre- exhibited no systematic bias that one could adjustlation between the CO measured by Doppler and that for.42,43 For these reasons, the bioimpedance tech-measured by thermodilution varied between Ϫ0.02 nique is hardly suitable for monitoring critically illand ϩ0.94.34 Equipment has improved and studies patients during laparoscopic–endoscopic operations.and reviews show that the correlation between Better results might be achieved with the oesophagealDoppler CO measurement and thermodilution is now placement of the electrodes.44 A more recent studymuch better.35–37 However, precision is still only fair as comparing bioimpedance CO measurements withmeasured by the limits of agreement between the thermodilution during major abdominal surgerymethods.38 Leather and Wouters demonstrated that a found poor agreement between the two methods andredistribution of blood ﬂow induced by lumbar a shift in measurement bias relative to changes inepidural anaesthesia changed the bias of oesophageal surgical conditions.45 Pulse contour monitoring and
50 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYthe Fick principle using CO2 are the two other non- patient with the typical vasoconstriction of pneu-invasive techniques for measuring CO.35 The former moperitoneum. These possible causes must be ruledis probably unreliable due to the changes induced by out before simply deepening the level of anaesthesia.the pneumoperitoneum, and the latter is obviously Table 4.4 gives a survey of points to be considered inuseless in laparoscopic surgery. haemodynamic monitoring.Despite its shortcomings, oesophageal Dopplersonography is, at present, probably the most suitable Neuromuscular monitoringnon-invasive method for monitoring CO in cardiacrisk patients. TEE gives information on myocardial Neuromuscular monitoring is particularly useful dur-contractility, ejection fraction and ventricular ﬁlling ing laparoscopic operations, since adequate relaxationand complements CO measurements. is required for optimal surgical access, while at the same time, one wishes to avoid residual curarization in the postoperative period.46,47 The latter aspect is Note Measurement of cardiac function and/or CO is especially important in view of the extremely short indicated in patients at high cardiac risk. times required for wound closure after minimally • Thermodilution: invasive but standardized and reli- invasive procedures. able if properly used • Doppler sonograph: non-invasive and fairly reliable Sophisticated monitoring methods are not required, • Bioimpedance: non-invasive but problematic with and train-of-four (TOF) stimulation with either tactile regard to reliability or quantitative evaluation (e.g. by accelerography) of • TEE: moderately invasive, excellent information on the twitch responses and the TOF ratio should suf- myocardial function and cardiac ﬁlling, little infor- ﬁce. The latter is the quotient obtained by dividing mation of CO, requires specialized training the response to the fourth stimulus by that to the ﬁrst stimulus. If there are fewer than four responses the TOF ratio is not calculated, and only the number ofDuring laparoscopic surgery, the process of distilling twitches is noted (TOF number). Residual relaxationclinical consequences from the haemodynamic moni- can be detected with double-burst stimulation (DBS)toring data must include careful differential diagnos- consisting of two short series of three stimuli each.48tic considerations. Changes in blood pressure and/orheart rate, especially increases, may occur in response Tactile assessment of the TOF is sufﬁcient for intra-to surgical stimuli and pain, and thus be an indication operative management of neuromuscular relaxation.of insufﬁcient anaesthesia, but not always. They A TOF number of 1–2 indicates an adequate degreemight also be the ﬁrst clinical signs of hypercapnia of myorelaxation for laparotomy, but there is no uni-(frequent), hypoxaemia (less frequent), gas embolism versally deﬁned level for laparoscopic procedures.(not uncommon), or relative hypovolaemia in a A twitch reduction of approximately 80%, indicated by two to three responses to TOF stimulation, will probably be sufﬁcient to obtain adequate compliance Table 4.4 Haemodynamic monitoring during laparo- of the abdomen. The presence of singultus will require scopic surgery further relaxation, since the diaphragm is less sensi- tive to the effect of non-depolarizing neuromuscular Patient status Suggested monitoring blockers than skeletal muscle. Tactile assessment Young, no cardiac 5-lead ECG, non-invasive alone is not sufﬁcient for determining eligibility for risks blood pressure monitoring tracheal extubation. Current guidelines require a TOF quotient of 0.9 or higher. Ischaemic heart 5-lead ECG with ST segment disease analysis, invasive blood The ulnar nerve – adductor pollicis muscle unit is pressure monitoring if normally employed for neuromuscular monitoring. hypertension a risk The ulnar nerve is stimulated with closely spaced sur- Congestive heart 5-lead ECG with ST segment face electrodes (ECG electrodes suitable) attached disease compensated analysis, invasive blood over the course of the nerve at the wrist. However, pressure monitoring, CVP since the patient’s arms are often positioned alongside Poorly compensated Additional cardiac function the body and are thus inaccessible for tactile or monitoring (pulmonary artery accelerographic monitoring, this nerve can only be catheter, oesophageal employed when the response is assessed by elec- Doppler, TEE, etc.). tromyography (e.g. Relaxograph®, Datex). One can
MONITORING 51also stimulate the facial nerve and assess relaxation as Temperature monitoringthe response of the orbicularis oculi or orbicularis orismuscle. The electrodes are placed over the course of Temperature monitoring is recommended duringthe nerve, one approximately over the condyle of the lengthy laparoscopic operations, since body tempera-temporal mandibular joint, and the second anterior to ture can decrease sharply, despite the smaller incisionthe ﬁrst (Figure 4.5). The current required for supra- and better insulation of the patient compared to con-maximal stimulation of the ulnar nerve is about ventional operations. Care must be taken not to pos-50–70 mA and approximately 30–40 mA for the facial ition the thermistor in the vicinity of the operationnerve. The orbicularis oculi muscle responds to neuro- site where there is considerable cooling.muscular blockers in a manner similar to that of thediaphragm.49 Using these muscles to guide the admin-istration of neuromuscular blockers will guarantee an Referencesadequately relaxed patient during the operation, butrecovery of the facial muscles may not indicate recov- 1. Hedenstierna G, Strandberg Å, Tokics L, Lundqvistery of muscular strength adequate for tracheal extuba- H, Brismar B. Correlation of gas exchange impairment to development of atelectasis during anesthesia andtion.50,51 Changes of skin or muscle temperature alter muscle paralysis. Acta Anaesthesiol Scand 1986; 30:the response to relaxometry.52,53 Response drift can 183–191.occur during lengthy operations that usually reduces 2. Raeder DB, Warren DL, Morris R, Philip BK, Philipthe amplitude of the ﬁrst twitch compared to base- JH. Hypoxemia during ambulatory gynecologic sur-line.54 Table 4.5 summarizes the basic principles of gery as evaluated by the pulse oximeter. J Clin Monitneuromuscular monitoring in laparoscopic surgery. 1987; 3: 244–248. 3. Tremper KK, Barker SJ. Pulse oximetry. Anesthesiology 1989; 70: 98–108. 4. Barker SJ, Tremper KK. The effect of carbon monoxide inhalation on pulse oximetry and transcutaneous PO2. Anesthesiology 1987; 66: 677–679. 5. Beebe DS, Swica H, Carlson N, Palahniuk RJ, Goodale RL. High levels of carbon monoxide are pro- duced by electro-cautery of tissue during laparoscopic cholecystectomy. Anesth Analg 1993; 77: 338–341. 6. Ott DE. Carboxyhemoglobinemia due to peritoneal smoke absorption from laser tissue combustion at laparoscopy. J Clin Laser Med Surg 1998; 16: 309–315. 7. Esper E, Russell TE, Coy B, Duke BEr, Max MH, Coil JA. Transperitoneal absorption of thermocautery- induced carbon monoxide formation during laparo- scopic cholecystectomy. Surg Laparosc Endosc 1994; 4: 333–335. 8. Eisenkraft JB. Pulse oximeter desaturation due to methemoglobinemia. Anesthesiology 1988; 68: 279–282. 9. Kessler MR, Eide T, Humayun B, Poppers PJ. Spurious pulse oximeter desaturation with methyleneFigure 4.5 Electrode placement for stimulating the facial blue injection. Anesthesiology 1986; 65: 435–436.nerve. Table 4.5 Clinical application of neuromuscular monitoring for laparoscopic surgery Phase of Relevant for Relaxometer Clinical signs operation Intraoperative Dosing TOF number 2–3 No pressing, no singultus T1 ϭ 10–20% Amply expanded pneumoperitoneum Emergence Extubation DBS without fading Elevate head from table and hold for TOF ratio у 0.9 at least 5 s TOF: four stimuli at a stimulation frequency of 2 Hz; TOF number: number of detectable responses to TOF stimulation; T1%: amplitude of ﬁrst TOF response as percentage of calibrated baseline without relaxation; TOF ratio: amplitude of fourth response divided by that of ﬁrst response T4/T1.
52 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY10. Heinonen J, Takki S, Tammisto T. Effect of 26. Kick O, Vanderneersch E, Mulier JP, Vermaut J, Van Trendelenburg tilt and other procedures on the pos- Aken H. Überwachung des Patienten im Aufwachraum. ition of endotracheal tubes. Lancet 1969; 1: 850–853. Anaesthesist 1992; 41: 331–334.11. Hamm P, Lang C, Fornecker ML, Bruant P, Vuillemin F. 27. Wimberley PD, Grønlund Pedersen K, Thode J, Fogh- Intubation bronchique séléctive à répétition au cours Andersen N, Møller Sørensen A, Siggaard-Andersen d’une cholécystectomie coelioscopique [Recurrent O. Transcutaneous and capillary pCO2 and pO2 meas- selective bronchial intubation in laparoscopic chole- urements in healthy adults. Clin Chem 1983; 29: cystectomy]. Ann Fr Anesth Reanim 1993; 12: 67–69. 1471–1473.12. Morimura N, Inoue K, Miwa T. Chest roentgenogram 28. Lemke R, Klaus D. 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ANAESTHESIA FOR LAPAROSCOPIC SURGERY 5Laparoscopy surgery requires a strategic reassess- drug delivery and anaesthetic depth monitoring arement and adaptation of anaesthetic management in now available that will allow optimal anaesthetic man-order to derive the greatest possible beneﬁt from the agement of minimally invasive operations with minimalprocedures on the one hand, and to anticipate the adverse effects and rapid awakening and recovery.speciﬁc risks and prevent the complications inherentin the technique on the other. When choosing the General anaesthesia with controlled ventilation is theanaesthetic, the anaesthetist must be fully aware that method of choice for nearly all minimally invasive pro-the main advantage of these minimally invasive surgi- cedures with only few possible exceptions. Controlledcal procedures is the shortened recovery period and mechanical ventilation is recommended to counteractthe intended rapid return of the patient to normal the hypercapnia and hypoxia due to impaired lungdaily life. The patient expects early mobilization, a function, and to meet the simultaneously increasedrapid return to oral feeding and prompt discharge ventilatory requirements. Even where this is not thefrom the hospital – frequently within 24 h after an case, the necessity of neuromuscular relaxation foruncomplicated laparoscopic cholecystectomy. This most laparoscopic operations would make mechanicalintended fast tracking should not be impeded by ventilation mandatory.postoperative impairment of the patient’s recovery byfatigue, lassitude, nausea and vomiting, vertigo orother adverse effects. Even after major operations, Airwaysuch as colectomy, nephrectomy or lymphadenec-tomy, oral ﬂuids are given on the day of surgery, oral Elevated intra-abdominal pressure (IAP) does not perfeeding is started on the ﬁrst postoperative day, and se increase the risk of regurgitating gastric contents,the patient is occasionally discharged from the hospi- but the risk is higher with the patient in thetal on the following day. Trendelenburg position. Endotracheal intubation pro- tects the airway and prevents aspiration pneumonitisA further aspect of minimally invasive surgery is the in these patients. Some authors see laparoscopic sur-drastic reduction of the time from when, for example, gery as an indication, or at least not a contraindication,the gall bladder is removed until when the wound is for use of the laryngeal mask airway,1,2 but theirsutured and dressed. Taking the altered time frame into enthusiasm is not shared by all.3 If one chooses to useconsideration, the anaesthetist can contribute to the a laryngeal airway, some authors recommend using thesmooth handling of the surgical schedule by ensuring ProSeal® model instead of the classic model, sinceshort turnover times between the individual patients. In they found it provided better ventilation during pneu-conventional surgery, the anaesthetic could be light- moperitoneum,4 and that it was equal to ventilationened while the peritoneum was being closed, the vari- with a cuffed endotracheal tube.5 Either would beous layers of the abdominal wall sutured and the suited for short diagnostic laparoscopies or fordressing applied, and the patient would be awake imme- extraperitoneal procedures such as hernia repair.6 Adiately afterward. The pharmacokinetics of the anaes- double lumen endotracheal tube should be used forthetic were not particularly crucial. This procedure is thoracoscopic operations in order to facilitate collapsenot possible with laparoscopic surgery, since wound of the lung on the side of the operation. This improvesclosure only consists of removing the instruments and surgical access, shortens the operating time and obvi-trocars and stitching up a few holes, and takes only few ates the necessity of intrathoracic gas insufﬂation withminutes. This means that a rapid offset and recovery is its associated complications.7the conditio sine qua non for an anaesthetic for minimallyinvasive surgery. New hypnotics, volatile anaesthet- The optimal anaesthetic for laparoscopic or thoraco-ics, opioids and neuromuscular blockers having the scopic operations is one that takes advantage of therequired pharmacokinetic–pharmacodynamic proper- excellent pharmacokinetics of drugs such as remifen-ties have been developed, and advanced methods of tanil, propofol, desﬂurane, isoﬂurane, mivacurium and
56 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYothers with rapid on–off characteristics. This can be a be the standard procedure, but the availability oftotal intravenous technique or a balanced technique excellent oral drugs and the knowledge that a sipwith an opioid and a volatile anaesthetic, as long as the of water with the tablet does not increase the riskcomponents are administered in a way to optimize of aspiration during induction has rendered thedepth of anaesthesia and recovery. We prefer a total intramuscular route obsolete. Antisialogogues are nointravenous technique with propofol as the hypnotic longer considered a mandatory component of theand remifentanil, since most meta-analyses have shown premedication, now that the use of ether has beenthat propofol is effective in preventing postoperative discontinued. When increased salivation might be anausea and vomiting (PONV), a complication other- problem, such as with a laryngeal mask airway orwise linked with laparoscopy.8,9 The newer drugs when ketamine is used, glycopyrrolate or atropine isrequired for these techniques are more expensive than given intravenously.old faithfuls like fentanyl, thiopental, pancuroniumand halothane, but they can be more cost effective byreducing the turnover time between patients and the Total intravenous anaesthesianeed for postoperative monitored care, while further-ing the goal of early mobilization and hospital dis- General remarkscharge. These drugs might not be available in every In the narrow deﬁnition of total intravenous anaesthe-institution or in every country. sia (TIVA), the components of anaesthesia – analgesia, hypnosis and muscle relaxation – are achieved solely with intravenously applied drugs, without usingPremedication inhalational agents. A totally intravenous technique with a rationally chosen combination of opioid, hypnoticWe recommend giving patients an oral premedication and neuromuscular blocker offers a number of advan-on the ward to provide anxiolysis before they are tages over other types of general anaesthesia. Thesebrought to the operating theatre, but this is not an advantages are associated with the pharmacologicalabsolute necessity and many institutions opt for an properties of the drugs themselves, but are also con-intravenous premedication in the holding area or for ferred by being able to avoid the undesired propertiesnone at all. When oral premedication is given, a drug of the drugs that can be dispensed with, for example,should be chosen that does not cause postoperative nitrous oxide (N2O). The choice of drugs for thedrowsiness. Short-acting oral benzodiazepines, such TIVA is governed by their pharmacokinetic proﬁlesas midazolam, lorazepam or temazepam, are good and by their effects on postoperative recovery.choices. The clinical effects of diazepam, ﬂuni- When comparing pharmacokinetic properties intrazepam, barbiturates or similar drugs last too long order to determine which drugs are best suited for anfor most minimally invasive procedures, and will anaesthetic for minimally invasive surgery, one shoulddelay awakening and interfere with the recovery not be obsessed with terminal elimination half-lives.period. Whichever drug one chooses, the correct dose Much more useful information is given by theand proper time of application are important toensure getting the maximum beneﬁt from the pre-medication. Midazolam has a rapid onset of action, Table 5.1 Premedication agents for minimally invasivebut must not be given too soon, since it also has a surgeryrapid offset and the sedative and anxiolytic effectsmight have evaporated before the patient is brought Drug Dose (mg) Administrationto surgery. Lorazepam, on the other hand, must be timegiven at least an hour before the patient is fetched Midazolam 7.5–15 20 min beforefrom the ward, since its effect sets in only slowly. transport to ORMany institutions choose to give an intravenous pre- Lorazepam 1–2 60 min beforemedication with a small dose of midazolam shortly transport to ORbefore induction. There are a number of studies Lormetazepam 1 60 min beforewhich show that this “co-induction” reduces the dose transport to ORof hypnotic needed to attain the targeted depth of Temazepam 20 30 min beforeanaesthesia.10,11 On the other hand, although the transport to ORpropofol dose required for induction is reduced, Other short-acting, Sufﬁciently earlyrecovery is prolonged, and this intravenous applica- anxiolytic sedatives to be effective Diazepam (not during transporttion does nothing to reduce the patient’s anxiety recommended)beforehand. Intramuscular premedication used to
A N A E S T H E S I A F O R L A PA R O S C O P I C S U R G E RY 57“context-sensitive half-time”. This is a measure of is 3.7 min for remifentanil, 34 min for sufentanil, 59 minhow long it takes for the concentration of a drug to for alfentanil and an incredible 262 min for fentanyl.15decrease by 50% in the effect site after having been The reason for this is that remifentanil is hydrolysedinfused for a deﬁned length of time, with the duration independent of speciﬁc organ function by ubiquitous,of the infusion being the context.12,13 The context- non-speciﬁc esterases in the blood and tissues, includ-sensitive half-times of a number of common drugs ing the brain to a virtually inactive metabolite andtogether with their elimination half-lives determined thus has an unusually high clearance of approximatelyin bolus injection studies are shown in Figure 5.1. 3000 ml minϪ1.15,16 Due to its large volume of distri-A further parameter that determines how easily the bution and low clearance, fentanyl is only suitable aseffects of a drug can be titrated to intraoperative a TIVA component for procedures lasting 20–30 mindemands is t ⁄ ke0. This is a constant that describes the 1 2equilibration rate between blood and the effect siteand is a measure of hysteresis, the delay betweenincreasing or decreasing plasma concentrations of the 100drug and a measurable change of its effect. Fentanyl (470) Time to 50% drop (min) 75Choice of opioid Alfentanil (110)There is one outstanding characteristic of most min- 50imally invasive operations that has a major inﬂuenceon the rational choice of opioid for the anaesthetic: 25 Sufentanil (580)the surgical stimulus is very intense up to within a Remifentanil (10)few minutes of the end of the operation, and the 0anaesthetic has to accommodate this fact. Under this 0 100 200 300 400 500 600constraint, remifentanil is, ﬁrst and foremost, the Infusion duration (min)opioid of choice for minimally invasive surgery.Sufentanil and alfentanil come in a distant second and Figure 5.1 Context-sensitive half-times of remifentanilthird, while fentanyl or morphine are unsuitable, and and other fentanyl congeners commonly used in TIVA tech-should be used only when nothing else is available niques. The numbers given after each substance is the ter-(Table 5.2). The computer simulation shown in minal elimination half-life (in min) after bolus application.Figure 5.1 illustrates that up to an infusion time of This is considerably longer than the context-sensitiveabout 6 h, sufentanil has a shorter context-sensitive half-time – the time required for the effect-site concentrationhalf-time than alfentanil, and thus potentially allows a to decrease by 50%, and there is no consistent relationship between the two parameters. This increases dramatically formore rapid awakening, despite its longer terminal fentanyl with increasing duration of infusion, but remainselimination half-life.14 Remifentanil occupies a special nearly constant at a very low level for remifentanil. The dia-position in the palette of opioids, in that its context- gram illustrates the point made in the text that remifentanilsensitive half-time remains virtually unchanged. The and sufentanil are the opioids most suited for use in a totallytime required for effect-site concentrations to decrease intravenous technique for minimally invasive surgery. (Adaptedby 50% after a constant rate infusion lasting 150 min from Egan, Anesthesiology 1993; 79: 881.) Table 5.2 Pharmacological properties of commonly used opioid Remifentanil Sufentanil Alfentanil Fentanyl Terminal elimination half-life t ⁄ (min) 1 2 10 164–570 110 390–450 Central distribution volume, Vc (l) 7.0 12 2.9 17 Steady-state distribution volume, Vss (l) 25–62 121 23 312 Clearance, Cl (ml minϪ1) ϳ3000 900 185 700 Protein binding at pH 7.4 (%) 92 92 92 84 pKa 7.1 8.0 6.5 8.4 Non-ionized at pH 7.4 (%) 67 20 89 9 Hepatic extraction ratio NR 0.7–0.9 0.3–0.5 0.8–1.0 Vc: initial volume of distribution in central compartment; Vss: volume of distribution in quasi-steady state; NR: not reported and not relevant for elimination.
58 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYat most.13 After this time, cumulation causes undue number of advantages over opioids. When used forprolongation of respiratory depression and retards TIVA in combination with propofol, it had a recoveryrecovery. A direct comparison of alfentanil and proﬁle similar to that of alfentanil–propofol combin-remifentanil in a total intravenous technique with ation.27 Dream events were more common on emer-propofol demonstrated more rapid recovery with gence, but were not unpleasant in content. A studyremifentanil, as measured by respiratory rate, oxygen comparing of propofol with ketamine or fentanyl for(O2) saturation and number of patients with an laparoscopic operations found that the only differenceAldrete score of 10 both after 10 and 30 min, even fol- was that the patients in the ketamine–propofol grouplowing short procedures lasting only 20 min.17 required more pain medication in the immediate post- operative period.28 However, it seems that the keta-Due to a combination of low degree of ionization mine dose of 1–1.5 mg kgϪ1 used in the study was lessand moderate plasma protein binding, remifentanil than equipotent with the 3–5 g kgϪ1 dose of fentanyl.and alfentanil both have very short onset times.Fentanyl and sufentanil have longer t ⁄ ke0 values and are 1 2more difﬁcult to adapt to rapid intraoperative changes Choice of the hypnotic componentin stimulus intensity. During laparoscopic surgery, theelimination of opioids with high hepatic extraction Propofol is essentially the only intravenous hypnoticmight be impaired due to the reduction in splanchnic that is suitable for use in a TIVA for minimally inva-and hepatic perfusion.18–20 This effect can be ampli- sive surgery. Methohexital and etomidate have similarﬁed by volatile anaesthetics, which reduce splanchnic elimination kinetics and clearance as propofol, and theperfusion. recovery time following their use is not relevantly different from that after propofol, but they have littleUnlike morphine, the newer opioids have only minor to offer in the way of advantages and a number ofeffects on the biliary system, an aspect that is relevant drawbacks. Etomidate might be nominally suitableduring laparoscopic cholecystectomy. Neither sufen- as a component of a TIVA, but it is associated withtanil nor fentanyl cause a narrowing of the common unpleasant awakening and a higher incidence ofbile duct.21 Fentanyl does signiﬁcantly increase the pres- PONV than after propofol.29–31 The well-known inhib-sure in the biliary system,22 but symptomatic choledo- ition of corticosteroid synthesis by etomidate is prob-choduodenal sphincter spasm is rare with its use.23 In a ably of no clinical consequence during short-termdirect comparison, alfentanil caused a lower and statis- administration, since it can be overcome if necessary.32tically insigniﬁcant pressure increase than fentanyl.22 Awakening takes longer,31,33 and the incidence of nauseaThe behaviour of remifentanil in this respect is not well and vomiting was reported to be higher after a TIVAknown. It has been shown to delay the drainage of with methohexital than after propofol,30,34 althoughradioactive dye into the duodenum,24 but this delay is other studies could not conﬁrm this ﬁnding.31,33 At anyshorter than with other studied opioids. rate, both substances are considerably more expensiveRemifentanil has one characteristic adverse effect, than propofol.and that is a high incidence of postoperative shivering The results of a number of studies suggest thatthat is not thermogenetic in nature and not correlated propofol has antiemetic properties and also inducesto intraoperative changes in core temperature.25,26 a slightly euphoric mood in the patients, a combina- tion of effects that greatly enhances patient satisfac- Note Opioids suitable for use as a component of a tion.29,35–37 Propofol occasionally causes pain on TIVA or a balanced anaesthetic for minimally invasive injection, but this can be attenuated or abolished surgery are: by applying a tourniquet to the forearm, injecting a small amount (2 ml) of 1% lidocaine into the vein • Remifentanil (e.g. Ultiva®) and waiting 10 s, or by waiting until the pre-injected • Sufentanil (e.g. Sufenta®) opioid has taken full effect (see below). This prag- • Alfentanil (e.g. Rapifen®) matic approach is supported by the results of a Less suitable are: recent study.38 A perhaps more academic concern is • Fentanyl, morphine and others that propofol in clinically relevant concentrations (IC50 ϳ 9 g mlϪ1) can inhibit alfentanil and sufen- tanil metabolism in human liver microsomes.39Ketamine should be mentioned when discussing the Propofol has also been described to reduce the centralanalgesic component of a total intravenous technique. volume of distribution of remifentanil by 41% and itsThis unique substance is used in anaesthesia for every clearance by 15%, but this was considered to be with-kind of surgery in many parts of the world, and it has a out clinical relevance.40
A N A E S T H E S I A F O R L A PA R O S C O P I C S U R G E RY 59Midazolam, which is occasionally used as a compon- 5–10 min. Muscle relaxation will have to let up sufﬁ-ent of TIVA for major surgery, is unsuitable in ciently during this short period to allow the patient’sthis role for minimally invasive procedures due to its trachea to be extubated immediately after wound clos-long duration of action.41 It can be used, however, ure. This can be achieved by properly timing theto reduce the dose of hypnotic necessary for loss of reversal of relaxation and employing higher doses ofconsciousness during induction of anaesthesia42,43 in cholinesterase inhibitors or by using a neuromusculara technique known as “co-induction”. blocker with a short recovery index, or a combination of the two. Table 5.3 gives a synopsis of the relevant pharmacological data on which a rational choice can be Note Hypnotics suitable for use in a TIVA for minimally based. The costs of neuromuscular blocking agents vary invasive surgery: widely and the newer, short-acting substances are the most expensive. However, understanding the actual • Propofol cost of a drug requires more than just looking at its shelf Perhaps price.44 A carefully performed study has shown that • Methohexital when not only the price of the muscle relaxant, but also the operating room (OR) costs incurred while waiting For co-induction for the effects to wear off were entered into the calcula- • Midazolam tion, the use of mivacurium led to a saving of approxi- mately £100 per patient over longer acting agents.45 We rarely reverse muscle relaxation, since this carries aChoice of neuromuscular blocking agent deﬁnite risk of its own, but instead prefer to use short- acting neuromuscular blockers with a rapid recoveryAdequate muscle relaxation increases the compliance index in combination with neuromuscular monitoring.of the abdomen, thus allowing better inﬂation of the Our choice of agent depends on the expected durationabdomen at a set IAP and thereby facilitating surgical of the operation. With a total expected anaesthesiaaccess. Muscle relaxation is therefore a crucial com- time of 2 h, we would use cisatracurium, vecuroniumponent of expert anaesthetic management. During or rocuronium with possibly a very slight top-uplaparoscopic cholecystectomy or other procedures, towards the end if relaxometry indicates a lightening ofdeep relaxation makes it easier for larger bits, for the block. If the block only had to be intensiﬁed toexample, the gall bladder, to be retrieved through the retrieve material at the end of the operation, we wouldsmall incision in the abdominal wall. Muscle relax- probably only give a small dose of succinylcholine. Foration will not always be necessary for extraperitoneal shorter operations, we would choose mivacurium oroperations, such as hernia repair or nephrectomy. perhaps only succinylcholine for very short diagnosticClose co-operation between surgeon and anaesthetist procedures. For longer operations we would also chooseis important in order to adapt the degree of neuromus- mivacurium, since its recovery index does not increasecular block to the individual stages of the operation. appreciably with the duration of its administration andIn laparoscopic surgery, the interval from when the sur- one can expect rapid termination of its effect even aftergeon concludes the intra-abdominal phase of the oper- an infusion lasting several hours. The effects of mivac-ation, which requires a good degree of myorelaxation, urium can be prolonged in patients with insufﬁcient orand ﬁnal wound closure with dressing is in the order of atypical cholinesterase.46,47 Table 5.3 Comparison of pharmacological variables of neuromuscular blockers for use in laparoscopic surgery ED95 Intubating dose Onset time RT25 RT90 Recovery index (mg kgϪ1) (mg kgϪ1) (min) (min) (min) (min) Atracurium 0.2 0.4–0.5 2–3 25 70 10–15 Cisatracurium 0.06 0.1–0.15 2–3 25 60 7–9 Mivacurium 0.08 0.2 1.5–2 15 30 6–8 Vecuronium 0.06 0.1 2–3 25 100 10–15 Rocuronium 0.25 0.6 1–1.5 45 90 14–22 Pancuronium 0.07 0.1 3–5 115 240 30–40 ED95: dose required to suppress the magnitude of the ﬁrst twitch (T1) by 95%; RT25, RT90: times to 25 and 90% recovery of ﬁrst twitch T1 after the injection of an intubating dose; recovery index: interval between 25 and 75% recovery of T1.
60 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYFuture pharmaceutical developments may make it pos- 35sible to speciﬁcally reverse the effect of rocuroniumrapidly and effectively without the adverse effects seenwhen cholinesterase inhibitors are administered. Stud- 30ies have shown that derivatives of cyclodextrine can besynthesized that chelate the rocuronium molecule ren-dering it inaccessible for the acetylcholine receptors of 25 Propofol (g mlϪ1)the neuromuscular junction. The chelated compoundis then excreted through the kidneys.48 One cyclodex- 20trine derivative (ORG 25969) is in pre-clinical test-ing. When given in a dose of 1 mg kgϪ1 this compound Cp95ishortens the recovery time t10–90 from 19 to 2.1 min.49 15 10 Note Neuromuscular blocking agents suitable for use in minimally invasive surgery: Cp50i • Mivacurium 5 • Rocuronium • Cisatracurium 0 • Vecuronium Opioid (ng mlϪ1) Figure 5.2 Isobologram showing the pharmacodynamicBasic dosage considerations interaction of propofol with an opioid. The curves give theKnowing the plasma or effect-site concentrations of 50 and 95% probability that the patient will tolerate a sur-the individual components required for hypnosis and gical stimulus at the chosen dosage combination of the twosurgical tolerance, and considering their additive or drugs. The dotted line is the hypnotic threshold for propofol; awareness becomes more likely at concentrations under thissynergistic interactions with one other, one can value.roughly calculate a rationally based dosage schedulefor a total intravenous technique based on pharmaco-kinetic and pharmacodynamic data. parameters.57–59,63 The results of these studies showThe hypnotic threshold plasma concentration of that a small opioid dose causes a steep reduction inpropofol given alone has been determined to be about the Cp50i of propofol, but that the interaction curve3–5 g mlϪ1.50–52 This is slightly lowered by the add- is hyperbolic, and the relative propofol-sparing effectition of an opioid.51,53,54 The plasma concentration of the opioid decreases at higher doses.required to suppress reaction to skin incision in 50% Since one can achieve the same effect with a propofol-of the patients (Cp50i) is reduced signiﬁcantly by the dominated or an opioid-dominated combination ofsimultaneous administration of a benzodiazepine or an dosages as illustrated by the isobolograms in Figureopioid. Premedication with midazolam, temazepam or 5.2, one should choose the combination which giveslorazepam alone reduces Cp50i by up to 50%.42,55,56 the shortest recovery time. This can be determinedSynergistic effects have been demonstrated between either clinically or theoretically using response sur-propofol and alfentanil or fentanyl by numerous face analysis.58,64 Just which dose combination this is,studies.51,57–60 A fentanyl plasma concentration of depends on the pharmacokinetics of the individual2–4 ng mlϪ1, corresponding to an induction dose of components. Let us just illustrate this concept with0.2 mg followed by a continuous infusion at a rate two extreme examples. In a combination of propofolof 2–3 g kgϪ1 hϪ1, reduces the Cp50i of propofol by with fentanyl, one would give a low dose of fentanyl80% to 2.7 g mlϪ1 (Figure 5.2).42,51 Equipotent and titrate the required depth of anaesthesia byplasma concentrations of sufentanil and alfentanil increasing the propofol dose. On the other hand, ifare 0.4–0.6 ng mlϪ1 and 100–300 ng mlϪ1, respec- one decided to combine thiopental with remifentanil,tively.61,62 Similar effects have been shown for the one would give the lowest possible thiopental dosecombination of alfentanil and propofol.60 A number just adequate to prevent awareness and give as muchof studies have demonstrated the synergistic inter- remifentanil as necessary to assure a sufﬁcient depthactions between propofol and remifentanil with regard of anaesthesia. Vuyk and co-workers did a computerto a number of clinical and electrophysiological simulation that illustrates this point quite nicely.64
A N A E S T H E S I A F O R L A PA R O S C O P I C S U R G E RY 61 Remifentanil 1 h in Alfentanil 1 h in Sufentanil 1 h in fusion fusio fusion n 40 40 40 30 30 30 ) ) in ) in in Time (m Time (m 20 20 Time (m 20 10 10 10 0 0 0 7 505 8 1.6 84 0.014 co co 2. 78 8 0. 23 nc 143 nc co 0 0 0 Re ratio 4. 8 0. 3 en 2 2 2 en nc Alf tion 43 209 43 m n 6.9 43 0.3 t tra en Su tion ife (n 6 5 65 65 en (n tra 1) ol mlϪ ) Ϫ1 ) nt g fen ( 1 lϪ tan g 8 8 ol 8 l ml pof pof g m ofo an m Pro n (g tan ng 10 Pro on ( 10 Prop n (g i l ml 10 il Ϫ .4412 tio 37312 ti .5912 tio i l ml 12 tra tra 0 tra cen cen cen l con Ϫ1 ) con con 1) Ϫ 1)Figure 5.3 Response surface analysis of varying combinations of propofol with remifentanil, alfentanil or sufentanil. Thecurve on the horizontal plane gives the isobolographic analysis of propofol–opioid dose combinations yielding a 50% prob-ability of no response to surgical stimuli. (Adapted from Ref .) The heavy line on the vertical curved plane gives theawakening time after a TIVA lasting 60 min with the various combinations of propofol with the individual opioids.Figure 5.3, adapted from this study, shows recovery and titrated to the patient’s needs. Pragmatically deter-times after a 1-h continuous infusion of propofol and mined dosage schedules will be described below.either remifentanil, alfentanil or sufentanil in varyinginfusion rate combinations, and demonstrates that There is no consensus on the degree of muscle relax-there is an optimal combination that has the most ation required for laparoscopic surgery. It might berapid recovery time. The results also give visible proof less than that necessary for laparotomy, where muscleof a number of points that have been mentioned so response has to be reduced by 80%, corresponding tofar. The ﬁrst of these is that awakening is faster after a one or two twitches following train-of-four (TOF)TIVA with remifentanil than with either alfentanil or stimulation. A reduction to two to four TOFsufentanil, and, secondly, that there is virtually no responses should be sufﬁcient to provide adequatedifference between alfentanil and sufentanil with abdominal compliance. Some patients develop recal-regard to recovery time after a 1-h infusion. citrant singultus during laparoscopic cholecystectomy that can effectively impede surgical preparation. TheAdding N2O to the combination of intravenous drugs diaphragm is much less sensitive to non-depolarizingwill reduce the required doses and possibly shorten neuromuscular blocks than skeletal muscle, and sin-recovery time.13,55,56,65 However, as described in more gultus can persist despite complete cessation of twitchdetail in Chapters 2, 6 and 10, N2O can be hazardous response to peripheral nerve stimulation. In these cases,when used during laparoscopic surgery or laser surgery the behaviour of the diaphragm will have to guide theof the upper airways, and one should try to avoid it. administration of the muscle relaxant.These theoretical considerations should demonstrate Despite all precautions, relaxation will be sufﬁcientlythat a combination of propofol and remifentanil after intense in some patients at the end of the operation asoral premedication with a short-acting benzodi- to prevent safe removal of the endotracheal tube. Forazepine, closely approaches the ideal TIVA for all high-risk patients, the best choice would be to continuetypes of minimally invasive surgery with regard to ventilation in the post-anaesthetic care unit until theease of titration to surgical needs, speed of recovery effects of the relaxant have worn off. In all others,and patient’s comfort and satisfaction. Sufentanil, reversal of the neuromuscular block is an option, butalfentanil or even fentanyl can be used instead of should not be attempted if the block is too intense, thatremifentanil in certain, clearly deﬁned situations, or is twitch strength is decreased by 85% or more, orwhen rapid awakening is not a requirement. there are fewer than two responses to TOF stimulation.The dosage recommendations based on pharmaco- Drug application systems for TIVAkinetic–pharmacodynamic data are only to be taken asguidelines for the initial settings. The actual values must For the safe, reliable and economical administrationbe adapted to the intensity of the surgical stimulation of a TIVA one requires the appropriate equipment.
62 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYThis includes the syringe pumps, infusion pumps to a microprocessor. There are a number of syringeand the correct infusion lines. Peristaltic infusion pumps now on the market that are programmed to keeppumps are used to control the rate of intravenous the plasma concentration of the infused drug at ainfusions, and when used for anaesthesia the drugs pre-set level by applying a target-controlled infusionare added to the infusion solution, usually normal (TCI) schedule. The ﬁrst of these, the Diprifusor® sys-saline or glucose, and infused at the required rate. tem developed by Kenny and co-workers, controls theThe one advantage of using such a dilute solution of infusion of propofol.68 The software in these pumpsthe drug is that, in a pinch, one can dispense with the incorporates a model based on pharmacokinetic datapump and regulate the infusion rate by adjusting the extracted from studies in thousands of patients and vol-drip rate.66 The main disadvantage is the large ﬂuid unteers. Administering an intravenous drug by setting avolume given to the patient. plasma concentration and not a drug dose takes some getting used to. On the other hand, it is no different thanSyringe pumps allow a precise application of concen- the way one administers inhalational anaesthesia – onetrated solutions of drugs in small volumes. For practical dials in the desired concentration and lets the vaporizerreasons to be mentioned below, the concentration of the or the TCI system give the required volume. Newerdrug should not be too high. A wide variety of syringe pump systems allow several drugs to be applied simulta-pumps are available on the market, and listing them neously as TCI, and allow one to target plasma concen-would not be feasible. They should have a minimal trations or effect-site concentrations (Figure 5.4).slack time, achieve the set infusion rate rapidly and beable to keep it constant to within Ϯ2% even at a slow When administering concentrated solutions ofrate, and should be able to accept a variety of different extremely potent drugs, one has to beware of inadver-syringe types. Particularly useful are microprocessor- tent bolus applications resulting from occlusion andcontrolled pumps that calculate the infusion rate from release of the infusion tubing. To prevent this, onlypatient’s weight, drug concentration and required non-compliant tubing should be used to connect thedosage in mg kgϪ1 hϪ1 or g kgϪ1 minϪ1 entered by the syringe pump to the patient, and the connectionanaesthetist. Some pumps have a pre-programmed, should be as close to the venous cannula as possible. Ifmenu-driven drug database that allows one to simply the drug is infused parallel to a running infusion, apick and choose the drug and concentration that one check valve should be used to prevent retrograde ﬁll-needs. All of these sophisticated pumps are more com- ing of the infusion system should the venous cannulaplicated and require more extensive training to use, but become occluded. The pump must be equipped withonce they are mastered they facilitate drug infusions an overpressure alarm, and should actively retract theand prevent mistakes resulting from calculation errors. syringe driver if the alarm is triggered to release pres- sure in the system. Low-volume, low-compliance sys-A constant rate infusion will lead to increasing plasma tems are available that also incorporate the checkconcentrations over time. Various ways of avoiding an valves (Figure 5.5). The drug delivery system must beoverdose towards the end of the anaesthetic or insufﬁ- secured against accidental disconnection that mightcient depth of anaesthesia at the beginning have been lead to intraoperative awakening of the patient.proposed. All of these are based more or less on thebolus, elimination, and transfer (BET) concept.67 Thebolus dose is calculated to saturate the central com- TIVA protocols for laparoscopicpartment to a pre-deﬁned initial plasma concentra- surgerytion, while the following infusion compensates for theamount of drug lost from this compartment by elimin- Various opioid–propofol combinations will be des-ation or transfer to more peripheral compartments. cribed in the following paragraphs. While opioid andThe rate of elimination remains relatively constant, propofol doses might differ, other components ofbut the amount of drug transferred into peripheral the totally intravenous anaesthetic always remain thecompartments decreases over time, necessitating a same. All patients are given an oral premedication asreduction in the infusion rate in order to keep the described above. Intubation is facilitated with a neuro-targeted plasma concentration constant. Examples muscular blocker chosen according to the criteriaof simple BET infusion schedules are given below. described above and dosed according to Table 5.3.Calculating the correct infusion rate required for a con- The initially chosen infusion rates of propofol andstant plasma concentration during the course of a total opioid that are based on the average patient may oftenintravenous technique entails repeatedly solving a num- not be adequate for the required plane of anaesthesia.ber of differential equations. This is not a task for the The standard procedure in this case is to increase thebusy operating theatre, but is just the thing to delegate dose of the analgesic under the assumption that it is
A N A E S T H E S I A F O R L A PA R O S C O P I C S U R G E RY 63Figure 5.4 An integrated system for administering TIVA. The TCI parameters are set on the control unit, and the calculatedplasma and effect-site concentrations of the individual drugs are displayed on the screen. The running infusion is controlledby the peristaltic pump seen at the top of the device. pain and not awareness that is causing the signs of too light anaesthesia. If two additional bolus injections of the opioid have no effect, a supplemental dose of the hypnotic is given. During laparoscopic surgery, one must be careful not to misinterpret the blood pressure increase regularly observed during abdominal inﬂa- tion as an indication that the anaesthetic has to be deepened. This is a trap into which the inexperienced anaesthetist frequently falls. Fortunately enough, the consequence of the anaesthetic overdose is usually only a prolongation of recovery time. Note Managing the TIVA: • Signs of insufﬁcient anaesthetic depth are ﬁrst treated with additional opioids • Supplemental doses of the hypnotic are given if theFigure 5.5 Infusion set for use with TIVA. Important fea- response to the opioid was inadequatetures are the low-volume, non-compliant tubing for con- Beware Blood pressure always increases during inﬂationnecting the syringes to the ﬂowing infusion (upper left and of the abdomen as part of the physiological response toright coils) and the check valves incorporated at relevant increased abdominal pressure. Differentiate as painpoints in the system. The short stretch of tubing seen on the response before treating with opioids or hypnotics!lower left is to reduce forces acting on the venous catheter.
64 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYTIVA with propofol–remifentanil infusion rate (in ml hϪ1) of this concentration is easilyRemifentanil differs in a very practical manner from calculated as the desired dose (in g kgϪ1 minϪ1)other frequently used opioids in that it must be given times body weight (in kg) times 60 (min) dividedas a constant infusion because of its extremely short by 10. For example, a 75 kg patient would requirehalf-life. Administering it in individual bolus doses is an infusion rate of 90 ml hϪ1 for a dose ofsimply not practical except for very short procedures. 0.2 g kgϪ1 minϪ1. Table 5.4 shows the preparation ofIf the expected duration of anaesthesia is longer than these solutions in detail.10–15 min, administering it as an infusion is neces- Anaesthesia is induced with 0.5–1 g kgϪ1 bodysary. A further consequence of the short elimination weight remifentanil given as a slow intravenous bolushalf-life is that its analgesic effects wear off rapidly injection, usually by letting the infusion run at a rateafter the infusion is stopped, and postoperative pain of 0.5 g kgϪ1 minϪ1 for 2 min. After the bolus injec-can set in early. The problems associated with this will tion, the infusion rate is set at the initial maintenancebe discussed in the section on postoperative pain rate of 0.2 g kgϪ1 minϪ1. As soon as the effect oftherapy. remifentanil sets in, propofol is given in an inductionRemifentanil’s rapid onset can cause vagomimetic dose of 1.5–2 mg kgϪ1 body weight and the pro-effects with profound bradycardia, particularly fol- pofol infusion is started at an initial rate oflowing the initial bolus injection, and atropine or gly- 6–7 mg kgϪ1 hϪ1. This is reduced after about 15 mincopyrrolate should be readily available. This does to a maintenance rate of 5 mg kgϪ1 hϪ1. As an alterna-not usually occur if the initial bolus is given slowly tive, propofol can be administered as a TCI. We setover 60–120 s. Like all intensely acting opioids with the initial target concentration at 4–5 g mlϪ1 and letrapid onset, remifentanil can induce signiﬁcant thorax the pump run until approximately 1.5–2 mg kgϪ1 ofrigidity, which can impair mask ventilation or even propofol have been administered. We then reduce therender it impossible. This adverse effect is less fre- target concentration to between 2 and 2.5 g mlϪ1.quent in patients who have been given a benzodi- This is, in effect, the intravenous counterpart of theazepine premedication. The rigidity responds to “overpressure” technique used to accelerate induc-neuromuscular blockers, and a small dose of succinyl- tion with inhalational anaesthetics. Our empiricalcholine (10 mg) can be administered, if ventilation is results are supported by the ﬁndings of a systematicseverely impaired. study, which showed that only 40% of the patients had lost consciousness after 3 min when the targetRemifentanil is supplied in powder form in vials con- concentration was set at 3 g mlϪ1 as opposed to 90%taining 1 or 5 mg. It has to be dissolved and diluted to when the concentration was set at 5 g mlϪ1.69the ﬁnal concentration in 0.9% NaCl or 5% glucosesolution before it is used. For use in adult patients we Signs of light anaesthesia are ﬁrst treated with a bolusdraw the contents of the 5 mg vial into a 50 ml syringe injection of 1 g kgϪ1 remifentanil that is repeatedfor a ﬁnal concentration of 100 g mlϪ1. The average after 2 min if there is no response to the ﬁrst dose. IfTIVA consumes approximately 1–2 mg of remifen- this is effective in restoring an adequate plane oftanil per hour. For paediatric anaesthesia, we prefer to anaesthesia the infusion rate of remifentanil isdissolve only 1 mg in 50 ml for a ﬁnal concentration of increased by 0.2–0.5 g kgϪ1 minϪ1. If the second20 g mlϪ1. We use this less concentrated solution injection of remifentanil is without effect, a bolusto avoid the very low infusion speeds, which not all injection of 0.6–0.8 mg kgϪ1 propofol is given, andsyringe pumps can reliably apply. If syringe pumps the infusion rate is increased by 1 mg kgϪ1 hϪ1. Bolusare not available, remifentanil can be diluted in injections are not possible with a TCI system, but wenormal saline and administered by infusion pump or circumvent this problem by increasing the targetedthrough a minidrip set.66 Five milligrams in 500 ml propofol plasma concentration to about 6 g mlϪ1solution yields a concentration of 10 mg mlϪ1. The until approximately 50 mg have been infused and then Table 5.4 Preparing remifentanil solutions for bolus injection and infusion Stock solution 5 mg in 5 ml (1 mg mlϪ1) Concentration for syringe pump for adults 5 ml stock solution in 50 ml (ϭ100 g mlϪ1) Concentration for bolus injections 1 ml of the syringe solution in 10 ml (ϭ10 g mlϪ1) When using remifentanil from the 1 mg vial, we recommend diluting it in at least 20 ml of liquid (ϭ50 g mlϪ1) to reduce the relative amount lost in the system dead space. Concentrations of 10–20 g mlϪ1 are recommended for use in children to avoid extremely low infusion rates.
A N A E S T H E S I A F O R L A PA R O S C O P I C S U R G E RY 65reducing the target concentration to 0.5 g mlϪ1 were 0.2 g kgϪ1 minϪ1 for remifentanil (range 0.05–above the previous level (see Table 5.5). 0.42) and 4.2 mg kgϪ1 hϪ1 for propofol (range 1.5–7.1). The patients awakened 4–9 min after the drug infu-If anaesthesia has been stable for 20 min or more under sions were stopped. The depth of anaesthesia was mon-a constant level of surgical stimulation, we tend to care- itored by bispectral index (BIS) (see Chapter 4). Thesefully reduce the infusion rates of propofol and remifen- empirically determined infusion rates are very similartanil in order to avoid unnecessarily deep anaesthesia. to those deﬁned by Vuyk on the basis of theoreticalThe median infusion rates required by our patients calculations aimed at determining the propofol– remifentanil combination with the shortest awaken- ing.64 These calculations recommend an initial Table 5.5 TIVA with propofol and remifentanil for min- remifentanil dose of 1.5–2 g kgϪ1 followed by an imally invasive surgery infusion rate of 0.37 g kgϪ1 minϪ1 for 20 min and Dissolve and dilute remifentanil according to Table 5.4 0.32 g kgϪ1 minϪ1 thereafter. Propofol is given as an Induction initial dose of 1.5 mg kgϪ1, followed by 8 mg kgϪ1 hϪ1 Remifentanil 0.5–1 g kgϪ1 slow bolus injection for the ﬁrst 40 min, 6.5 mg kgϪ1 hϪ1 for the next 150 min or 0.5 g kgϪ1 minϪ1 for 2 min and 6 mg kgϪ1 hϪ1 from then on. The propofol plasma and concentration targeted by this infusion regimen is Propofol 1.5–2 mg kgϪ1 2.8 g mlϪ1, which the authors describe as sufﬁcient to or suppress response to surgical stimuli in 95% of the Propofol TCI Target plasma concentration patients when given with remifentanil (Table 5.8). The 4–5 g mlϪ1 awakening time after this combination is around 6 min. Until 1.5–2 g kgϪ1 have been infused Then Target plasma concentration 2.0–2.5 g mlϪ1 TIVA with propofol–sufentanil Maintenance We found that when combined with propofol infused Remifentanil 0.2 g kgϪ1 minϪ1 initial infusion rate at a rate of 6 mg kgϪ1 hϪ1, a median sufentanil dose Propofol 6–7 mg kgϪ1 hϪ1 for 15 min of 0.3 g kgϪ1 hϪ1 was sufﬁcient to provide haemo- 5 mg kgϪ1 hϪ1 thereafter dynamic stability and prevent response to surgical stim- or uli during laparoscopic cholecystectomy. Anaesthesia Propofol TCI Target plasma concentration 2.0–2.5 g mlϪ1 is induced with a bolus injection of 0.2–0.3 g kgϪ1 sufentanil followed by an infusion with an initial rate Intubation of 0.2 g kgϪ1 hϪ1. We use a sufentanil solution con- Endotracheal tube or laryngeal mask airway taining 5 g mlϪ1 in order to have manageable infu- Ventilation sion rates. The onset time is slower with sufentanil With O2–air and minute volume adjusted to eliminate than with remifentanil and one must wait 4 or 5 min excess carbon dioxide (CO2) for an appreciable effect to set it. Propofol is then If anaesthesia too light given as an induction dose of 1–1.5 mg kgϪ1, followed Remifentanil 1 g kgϪ1 bolus injection, repeated by an infusion at a rate of 5–6 mg kgϪ1 hϪ1, which is after 2 min, if necessary if opioid effective, increase infusion rate by then reduced to 4–5 mg kgϪ1 hϪ1 after 10 min (Table 0.2–0.5 g kgϪ1 minϪ1 5.6). This differs slightly from the theoretical dosage If opioid ineffective recommendations of Vuyk shown in Table 5.8.64 Propofol 0.6–0.8 mg kgϪ1 bolus injection and As with the remifentanil–propofol combination, light Increase infusion rate by anaesthesia is ﬁrst treated with an additional dose of 1 mg kgϪ1 hϪ1 the opioid; in this case, a bolus injection of 3–5 g Propofol TCI Set target concentration to 6 g mlϪ1 sufentanil. This is repeated after 5 min if the ﬁrst until ca. 40–60 mg infused Increase target concentration by 0.5 g mlϪ1 injection is without effect. If the additional opioid dose attenuates the patient’s response to surgical Anaesthesia stable for 20 min stimulation, the sufentanil infusion rate is increased Careful stepwise reduction of drug infusion rates Do not reduce propofol infusion rate below 4 mg kgϪ1 hϪ1 by 0.05 g kgϪ1 hϪ1. If the opioid is not effective, a bolus injection of propofol is administered and the End infusion rate is changed as described above. If every- Stop infusions of remifentanil and propofol about 3 min before last stitch. thing has remained stable for 20 min or more, we reduce the propofol and sufentanil doses in steps, as Cave! described above for the remifentanil–propofol com- Pain can set in early. Prophylactic analgesics. bination, starting with the opioid (see Table 5.6).
66 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Table 5.6 TIVA with propofol and sufentanil for mini- Table 5.7 TIVA with propofol and alfentanil for minimally mally invasive surgery invasive surgery Induction Induction Sufentanil 0.2–0.3 g kgϪ1 bolus injection, Alfentanil 20–30 g kgϪ1 bolus injection wait at least 2–3 min (ca. 1.5–2 mg) Then then Propofol 1.5–2 mg kgϪ1 bolus injection Propofol 1–1.5 mg kgϪ1 bolus injection or or Propofol TCI Target plasma concentration Propofol TCI Target plasma concentration 4–5 g mlϪ1 4–5 g mlϪ1 Until 1.5–2 g kgϪ1 have been infused Until 1.5–2 g kgϪ1 have been infused Then Target plasma concentration then Target plasma concentration 2.0–2.5 g mlϪ1 2.0–2.5 g mlϪ1 Maintenance Maintenance Sufentanil 0.2 g kgϪ1 hϪ1 initial infusion rate Alfentanil 25–35 g kgϪ1 hϪ1 initial infusion rate or 3–5 g bolus injections as necessary or 0.5–1.0 mg bolus injections as necessary Propofol 8–10 mg kgϪ1 hϪ1 for 10 min, then Propofol 8–10 mg kgϪ1 hϪ1 for 10 min, 5 mg kgϪ1 hϪ1 thereafter then Propofol TCI Target concentration 2.0–2.5 g mlϪ1 5–6 mg kgϪ1 hϪ1 thereafter Propofol TCI Target concentration 2.0–2.5 g mlϪ1 Intubation Endotracheal tube or laryngeal mask airway Intubation Endotracheal tube or laryngeal mask airway Ventilation With O2–air and minute volume adjusted to eliminate Ventilation excess CO2 With O2–air and minute volume adjusted to eliminate excess CO2 If anaesthesia too light If anaesthesia too light Sufentanil 3–5 g kgϪ1 bolus injection, Alfentanil 0.5–1 mg bolus injection, repeated repeated after 5 min, if necessary after 3 min, if necessary If opioid effective, increase infusion If opioid effective, increase infusion rate by 0.05 g kgϪ1 rate by 5 g kgϪ1 hϪ1 If opioid effective, increase If opioid ineffective Propofol infusion rate by 0.05 g kgϪ1 hϪ1 Propofol 0.6–0.8 mg kgϪ1 bolus injection and If opioid ineffective Increase infusion rate by 1 mg kgϪ1 hϪ1 0.6–0.8 mg kgϪ1 bolus injection and Propofol TCI Set target concentration to 6 g mlϪ1 Increase infusion rate by mg kgϪ1 hϪ1 until ca. 40–60 mg infused Propofol TCI Set target concentration to 6 g mlϪ1 Increase target concentration by until ca. 40–60 mg infused increase 0.5 g mlϪ1 target concentration by 0.5 g mlϪ1 Anaesthesia stable for 20 min Anaesthesia stable for 20 min Careful stepwise reduction of drug infusion rates Careful stepwise reduction of drug infusion rates Do not reduce propofol below 4 mg kgϪ1 hϪ1 Do not reduce propofol below 4 mg kgϪ1 hϪ1 End End Last alfentanil ca. 20–30 min before end of surgery Last sufentanil ca. 20–30 min before end of surgery Stop propofol infusion ca. 3 min before last stitch Stop propofol infusion about 5 min before last stitch and dressing. Tip: Dilute sufentanil to a concentration of 5 g mlϪ1 to onset of its effects, but it has the disadvantage of being facilitate handling and to avoid low infusion rates. much more expensive than sufentanil in many countries. Our studies showed that an infusion rate of 25– 35 g kgϪ1 hϪ1, or approximately 2.5 Ϯ 1.0 mg hϪ1, in combination with propofol gave a sufﬁciently intenseTIVA with propofol–alfentanil analgesia for laparoscopic cholecystectomy. The neces-The combination of propofol and alfentanil is also suit- sary infusion rate was virtually the same for herniotomyable for minimally invasive surgery lasting up to about and other laparoscopic operations. Propofol was given60 min. The time to awakening is essentially the same as as an induction dose of 1–1.5 mg kgϪ1 followed byafter a total intravenous technique with propofol and an infusion of 6 mg kgϪ1 hϪ1 that was reduced tosufentanil. Alfentanil has the advantage of a more rapid 4–5 mg kgϪ1 hϪ1 after 10 min. Alfentanil can also be
A N A E S T H E S I A F O R L A PA R O S C O P I C S U R G E RY 67 Table 5.8 Infusion rates of remifentanil, sufentanil or alfentanil in combination with propofol calculated to give a 95% probability of no response to surgical stimulation and to have the most rapid recovery times (Vuyk, et al.64) Remifentanil Sufentanil Alfentanil Without propofol Target concentration 8.0 ng mlϪ1 0.2 ng mlϪ1 130 ng mlϪ1 Infusion rates Bolus 1.5–2 g kgϪ1 0.25 g kgϪ1 35 g kgϪ1 Infusion 1 22 g kgϪ1 minϪ1 for 20 min 0.22 g kgϪ1 hϪ1 75 g kgϪ1 hϪ1 for 30 min Infusion 2 19 g kgϪ1 minϪ1 thereafter 0.22 g kgϪ1 hϪ1 42.5 g kgϪ1 hϪ1 thereafter With propofol Target concentration 2.8 g mlϪ1 4.5 g mlϪ1 4.4 g mlϪ1 Infusion rates Bolus 1.5 mg kgϪ1 2.8 mg kgϪ1 2.8 mg kgϪ1 Infusion 1 8 mg kgϪ1 hϪ1 for 40 min 12 mg kgϪ1 hϪ1 for 40 min 12 mg kgϪ1 hϪ1 for 40 min Infusion 2 6.5 mg kgϪ1 hϪ1 for 150 min 10 mg kgϪ1 hϪ1 for 150 min 10 mg kgϪ1 hϪ1 for 150 min Infusion 3 6 mg kgϪ1 hϪ1 thereafter 8 mg kgϪ1 hϪ1 thereafter 8 mg kgϪ1 hϪ1 thereaftersimply given at a set rate of 2 mg hϪ1 and supplemented The increase of systemic vascular resistance duringwith bolus injections of 0.5 mg if necessary. If two or laparoscopic surgery is accompanied by a markedmore additional injections are required in a 10-min vasoconstriction in the splanchnic vascular bed. Theperiod, the infusion rate is increased by 0.5 mg hϪ1. resulting decrease in hepatic portal blood ﬂow mightHere, as with the other total intravenous technique, the increase the risk of liver damage by anaerobic halo-infusion rates can be gradually reduced when the thane metabolism. Halothane also increases the riskcourse has been stable for a reasonable length of time of cardiac dysrhythmias due to CO2 absorption and(Table 5.7). hypercarbia.75Our clinically determined combination of alfentanil It should be obvious that an inhalational monoanaes-and propofol is less propofol-dominated than that thetic is not suitable for minimally invasive surgery.calculated by Vuyk64 (see Table 5.8). One possible exception might be desﬂurane with its low solubility, although it would be difﬁcult to ﬁndInhalational anaesthetics and convincing arguments for using it alone. The classical method for reducing the alveolar concentration of thebalanced anaesthesia volatile agent required for surgical tolerance is to combine it with N2O. N2O will be discussed shortly atA monoanaesthetic with a volatile agent has the disad- the end of this section. It is dealt with in Chapter 2vantage of delayed recovery, perhaps with the excep- and will ﬁgure prominently in Chapter 6. A furthertion of desﬂurane. Time to awakening after a 90 min way to reduce the required alveolar concentration isadministration of 1.5 minimal alveolar concentration to combine the volatile with an opioid. This will be(MAC ) of isoﬂurane, enﬂurane or sevoﬂurane is more described in the following paragraphs.than 30 min. This would slow patient turnover, seri-ously interfere with rational utilization of operatingcapacity and incurs costs far higher than potential Notesavings from the use of inexpensive volatiles. • Monoanaesthetic with an inhalational agent is notVolatile anaesthetics have the further disadvantage that suited for minimally invasive surgerythey decrease hypoxic pulmonary vasoconstriction • The hypnotic effects of inhalational anaesthetics in low concentrations can be exploited in a balanced(HPV).70–72 This vascular reﬂex reduces the perfusion anaestheticof non-ventilated alveoli and diminishes the magni-tude of pulmonary shunt perfusion (Q S/Q T). Theextent of non-ventilated lung areas and consequently Balanced anaesthesia, the combination of an opioidQ S/Q T is increased by controlled ventilation, the with a volatile anaesthetic, can be used to advantage inhead-down position and elevated IAP.73,74 Interfering minimally invasive surgery. As with propofol, the add-with hypoxic vasoconstriction will cause a greater ition of an opioid causes a dramatic reduction in thedegree of arterial O2 desaturation at a constant inspira- alveolar concentration of the inhalational anaesthetictory O2 concentration. This effect is enhanced by N2O. required for hypnosis as well as suppressing response
68 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY inhalational agents. The opioid is given at the same Table 5.9 Reduction of isoﬂurane minimal alveolar concentration by opioids dosage as described above for TIVA. Signs of a too light plane of anaesthesia are initially treated with Opioid MAC reduction Source additional bolus injections of the opioid. (50% at) We compared a balanced anaesthetic with isoﬂurane Fentanyl 1.67 ng mlϪ1 McEwan et al.76 and alfentanil to a total intravenous technique with Sufentanil 0.145 ng mlϪ1 Brunner et al.77 propofol and alfentanil for laparoscopic cholecystec- Alfentanil 28.8 ng mlϪ1 Westmoreland et al.80 tomy. Isoﬂurane was given at an end-tidal concentra- Remifentanil 1.37 ng mlϪ1 Lang et al.79 tion of 0.6% (0.5 MAC), while alfentanil was infused as described above for the TIVA. Median awaken- ing time after the balanced technique was 14 minto painful stimulation.76–83 Whereas an alveolar con- compared to 12 min after the TIVA (Crozier et al.,centration of 1.5–2 MAC is required to produce a sufﬁ- unpublished data).ciently deep plane of anaesthesia when used alone, onlyabout 0.5–0.8 MAC is necessary with the simultaneous Remifentanil is an excellent combination partneradministration of a relatively small dose of an opioid. for balanced anaesthesia. In one study comparingFor example, about 1 mg of alfentanil reduces the MAC isoﬂurane–remifentanil and propofol–remifentanil forof isoﬂurane by more than 50%.80 Equianalgesic doses arthroscopy lasting about 80 min, the patients withof other opioids will have the same effect (Table 5.9). the balanced anaesthetic were awake after an averageUsing this combination not only reduces the recovery of 6.7 min, while the mean awakening time followingtime but also the adverse effects associated with the use the total intravenous technique was 9.6 min.84 Theof high concentrations of volatile anaesthetics. Volatile need for postoperative supplemental analgesics andanaesthetics have the one advantage over short-acting the incidence of adverse events were the same in bothhypnotics that they are virtually ubiquitously available groups, although the patients requested the ﬁrst anal-and do not require additional equipment, such as gesic earlier after the balanced technique. Table 5.10syringe pumps, for their exact administration. describes a balanced anaesthetic with isoﬂurane orThe ideal balanced anaesthetic combines a poorly sol- desﬂurane combined with remifentanil or alfentanil.uble inhalational anaesthetic and an opioid with a One study compared desﬂurane–remifentanil withshort context-sensitive half-time that is not affected propofol–remifentanil for laparoscopic cholecystec-by changes in hepatic perfusion. The inhalational tomy.85 Time to extubation was 5–6 min in bothagent of choice should be eliminated rapidly with little groups, but the patients with the balanced anaestheticor no metabolism, should be without relevant side required more supplemental opioid analgesics andeffects and should not interfere with the elimination had a higher incidence of nausea and vomiting.of other drugs. The ﬁrst choice would be isoﬂurane ordesﬂurane followed by sevoﬂurane and perhaps enﬂu-rane. The high lipid solubility of halothane, along Nitrous oxidewith its pronounced metabolism, its sensitization ofthe myocardium to the dysrhythmogenic effects of The use of N2O for laparoscopic surgery is problem-catecholamines, and its inhibition of opioid clearance, atic for two reasons. One of these is the distension ofmake it a poor choice. hollow viscera caused by the diffusion of N2O into air-ﬁlled spaces. The volume of the stomach and Note Suitable components of a balanced anaesthetic intestines was doubled after a 2-h anaesthetic with for minimally invasive surgery: N2O;86 an effect that can interfere with surgical access Inhalational agents and impede the course of the operation, if the bowels Isoﬂurane, desﬂurane, sevoﬂurane and enﬂurane are not prepared and the stomach not emptied of gas Opioids prior to surgery.87 This might only be an academic Remifentanil, sufentanil and alfentanil worry, since surgeons were unable to tell if N2O had Halothane and fentanyl are unsuitable and are not been used for the anaesthetic during a 75 min laparo- recommended. scopic cholecystectomy, and were not hampered by bowel distension.88 However, this might be an issue in operations lasting several hours. It is our experienceThe volatile anaesthetic is administered in an end- that surgical access for laparoscopic fundoplication istidal concentration that will ensure lack of intraoper- considerably impaired by distended bowel loops afterative awareness. This is about 0.5–0.7 MAC for all several hours of N2O anaesthesia.
A N A E S T H E S I A F O R L A PA R O S C O P I C S U R G E RY 69 Table 5.10 Balanced anaesthesia with isoﬂurane or desﬂurane with remifentanil or alfentanil for minimally invasive surgery Induction Remifentanil 0.5–1 g kgϪ1 bolus injection and infusion or Alfentanil 20–30 g kgϪ1 bolus injection (ca. 1.5–2 mg) then Propofol 1.5–2.0 mg kgϪ1 bolus injection Maintenance Isoﬂurane End-tidal concentration should be around 0.7–0.9% (ca. 0.5 MAC) Desﬂurane End-tidal concentration should be around 4–5% (higher if using alfentanil) Remifentanil 0.2 g kgϪ1 minϪ1 or Alfentanil 25–35 g kgϪ1 hϪ1 (ca. 2–3 mg hϪ1) Intubation Endotracheal tube or laryngeal mask airway Ventilation With O2–air and minute volume adjusted to eliminate excess CO2 The ﬁrst measure at signs of too light anaesthesia is to give a supplemental dose of the opioid. If the ﬁrst dose is not sufﬁciently effective it is repeated once more after several minutes. If the second dose is also without effect, the inspiratory concentration of the volatile anaesthetic is increased. End Last alfentanil ca. 20–30 min before end of surgery Slightly reduce ventilation, allow patient to breathe spontaneously (but avoid hypoventilation) Stop remifentanil infusion 3 min before last stitch Stop isoﬂurane when instruments are removed; desﬂurane slightly laterA further reason not to use N2O in an anaesthetic for Laparoscopy was once thought to be a risk factor forlaparoscopic surgery is that it can delay the dissolution PONV, but this has not been conﬁrmed in controlledof gas bubbles in the circulation,89 even if these con- studies. Large studies on thousands of patients havetain only CO2. This increases the risk of clinically rel- distilled four factors that predict the likelihood ofevant pulmonary gas embolism, particularly during PONV. These are female gender, non-smoker, a historyintra-abdominal laser surgery.90 of travel sickness or PONV and postoperative opioid administration.95 Female patients suffer from PONVA ﬁnal controversy revolves around the question of three times more frequently than males.95,96 Non-whether N2O increases the incidence of PONV.35,91–93 smokers are at increased risk of PONV,96 as are patientsIf it did increase postoperative emesis even slightly, with a history of PONV or travel sickness.95–97 Theits use would contravene one of the basic intentions of ﬁrst three factors are beyond the control of the anaes-minimally invasive surgery. thetist, but he or she can still inﬂuence the risk of PONV to a certain degree by carefully planning the Note management of the anaesthetic and postoperative pain relief. Opioids given for postoperative pain control are • N2O enhances the circulatory effects of entrained the fourth major risk factor for PONV,95,96 and their venous gas and reduces the volume of entrained gas required to cause a lethal embolism use can be minimized by rational planning of analgesic • N2O can easily be dispensed with for anaesthesia regimens (see Chapter 7). Volatile anaesthetics increase the risk of PONV,98 and simply avoiding their use reduces the incidence by 18%.99 Eliminating N2O from the anaesthetic regimen probably decreases the inci-Postoperative nausea and dence of PONV.9,100 Reversing the effects of the neuro-vomiting muscular blockers with neostigmine is a further factor that increases PONV.101PONV is one of the two major factors preventingearly discharge after day-care surgery and is also a Effective measures for the treatment and prophylaxismajor reason for re-admission to the hospital. It sig- of PONV have been determined by countless clinicalniﬁcantly increases the costs of monitoring, nursing studies. 5-HT3 receptor antagonists are the drugs ofand treatment, and is rivalled only by pain as a cause ﬁrst choice for treating PONV, followed by antihista-of patient discomfort.94 Prevention of PONV is an mines, such as dimenhydrinate or cyclizine, andimportant contribution to the rational management of droperidol. Metoclopramide has been shown to bepatients undergoing minimally invasive surgery. ineffective.102 Scopolamine is a popular substance,
70 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYbut its efﬁcacy in the treatment of PONV is limited, not always assured, it has been performed successfully.and its high incidence of adverse effects, such as In one institution, epidural anaesthesia is the methodvisual disturbances, dry mouth, dizziness and agita- of choice for laparoscopic cholecystectomy in patientstion, will limit its usefulness.103 Dexamethasone has with severe obstructive lung disease,114 while Edelmanbeen demonstrated to be effective in the prevention, and colleagues described a laparoscopic cholecystec-but not in the treatment of PONV.104 tomy performed under epidural anaesthesia during pregnancy.115The overall probability of PONV is 10% in patientswithout risk factors. The presence of one, two, three Regional anaesthesia is not feasible as the sole anaes-or four risk factors is associated with an incidence of thetic for thoracoscopic operations in any case. ForPONV of 20, 40, 60 and 80%, respectively.105,106 laparoscopic procedures, the level of anaesthesia has toCurrent recommendations for PONV prophylaxis reach Th4 to completely block all peritoneal afferents,incorporate this observation into a graded, multimodal but segments Th1 to Th4 should be spared to avoidapproach.107,108 Patients at moderate risk for PONV blocking the thoracic sympathetic accelerant nerves.(one risk factor) should be given a TIVA without N2O This is hardly possible, since the extent of sympatheticand a prophylactic dose of an antiemetic, preferably block usually exceeds that of analgesia, and there will be4 mg dexamethasone. In addition to these measures, a risk of severe bradycardia during pneumoperitoneum.patients at high risk (two or more risk factor) should Increased abdominal pressure impeding breathing, abe given a prophylactic dose of a second antiemetic. head-down position and other associated factors causePatients with failed prophylaxis should not be given a severe distress in some patients that can interfere withsecond dose of the prophylactic agent, but one acting surgery or even render it impossible to complete. Theat a different site. increased respiratory efforts required to eliminate excess CO2 can cause considerable movement in theRegional and local anaesthesia surgical ﬁeld making delicate work increasingly difﬁ- cult. Gas-free abdominal wall lift techniques that doRegional or local anaesthesia has the advantage that the not require increased IAP might avoid these problems.patient is awake and can be rapidly mobilized as soon as It remains to be seen if regional anaesthesia is a suit-the motor blockade recedes. Some authors see a further able method for extraperitoneal procedures, such asadvantage in the fact that the patient can automatically hernia repair. The extremely high CO2 uptake fromadapt his alveolar ventilation to eliminate absorbed the tissues will impose a heavy demand on the venti-CO2. But there are only very few laparoscopic or endo- latory capacity that the patient might not be willing toscopic procedures that could be carried out under tolerate or even be physically able to cope with. Gas-regional or local anaesthesia. The choice is severely free techniques might offer an acceptable alternative.limited by the physiological consequences of the oper-ation, the pain localization and, above all, the patient’spossible reluctance to accept the technique. Regional Fluid management duringanaesthesia is most useful for short procedures withlow-pressure pneumoperitoneum, with at most a laparoscopic surgeryslightly head-down position and without expected sur- The elevated IAP of pneumoperitoneum establishes agical complications (e.g. adhesions). Among these are pressure gradient between the intra-abdominal andlaparoscopic tubal ligation, diagnostic procedures, intrathoracic segments of the inferior vena cava thatgamete transfer, cryptorchism, etc. Laparoscopic tubal interferes with venous return to the heart and thusligation is frequently performed in spinal or local induces circulatory changes resembling those seenanaesthesia.109,110 N2O is recommended as insufﬂation in hypovolaemia. Hypotension is absent only becausegas instead of CO2 for laparoscopy with local anaesthe- pneumoperitoneum increases peripheral vascular resist-sia, since it causes less peritoneal irritation and is bet- ance. This is usually clinically irrelevant for short pro-ter tolerated by the patient.109 Extraperitoneal hernia cedures or for surgery in the Trendelenburg position.repair is a further indication for epidural anaesthe- Occasionally, however, this relative hypovolaemia cansia,111–113 however, conversion to general anaesthesia contribute to signiﬁcant intraoperative hypotension.can become necessary if the peritoneum is perforated. This is particularly the case in operations, such asAlthough regional anaesthesia is not generally recom- retroperitoneal laparoscopic adrenalectomy, in whichmended for upper abdominal surgery, since part of the patient’s legs are lowered and there is no pneu-the afferent innervation runs through the vagus and moperitoneum to stimulate cardiovascular responses.phrenic nerves, and complete sensory blockade is Bandages or elastic stockings can be useful in preventing
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A N A E S T H E S I A F O R L A PA R O S C O P I C S U R G E RY 7356. Davidson JAH, Macleod AD, Howie JC, White M, 72. Bjertnæs LJ. Hypoxia-induced vasoconstriction in iso- Kenny GNC. Effective concentration 50 for propofol lated perfused lungs exposed to injectable or inhalation with and without 67% nitrous oxide. Acta Anaesthesiol anesthetics. Acta Anaesthesiol Scand 1977; 21: 133–147. Scand 1993; 37: 458–464. 73. Hedenstierna G. Gas exchange during anaesthesia. Br57. Bouillon TW, Bruhn J, Radulescu L et al. Pharmaco- J Anaesth 1990; 64: 507–514. dynamic interaction between propofol and remifen- 74. Hedenstierna G, Strandberg Å, Tokics L, Lundqvist H, tanil regarding hypnosis, tolerance of laryngoscopy, Brismar B. Correlation of gas exchange impairment to bispectral index, and electroencephalographic approxi- development of atelectasis during anesthesia and mus- mate entropy. Anesthesiology 2004; 100: 1353–1372. cle paralysis. Acta Anaesthesiol Scand 1986; 30:58. Kern SE, Xie G, White JL, Egan TD. A response sur- 183–191. face analysis of propofol–remifentanil pharmaco- 75. Scott DB, Julian DG. Observations on cardiac arrhyth- dynamic interaction in volunteers. Anesthesiology 2004; mias during laparoscopy. Br Med J 1972; 12: 411–413. 100: 1373–1381. 76. McEwan AI, Smith C, Dyar O, Goodman D,59. Milne SE, Kenny GN, Schraag S. Propofol sparing Glass PSA. Isoﬂurane MAC reduction by fentanyl. effect of remifentanil using closed-loop anaesthesia. Anesthesiology 1993; 78: 864–869. Br J Anaesth 2003; 90: 623–629. 77. Brunner MD, Braithwaite P, Jhaveri R et al. MAC60. Vuyk J, Lim T, Engbers FH, Burm AG, Vletter AA, reduction of isoﬂurane by sufentanil. Br J Anaesth Bovill JG. The pharmacodynamic interaction of 1994; 72: 42–46. propofol and alfentanil during lower abdominal sur- 78. Lake CL, DiFazio CA, Moscicki JC, Engle JS. gery in women. Anesthesiology 1995; 83: 8–22. Reduction of halothane MAC: comparison of61. White PF, Coe V, Shafer A, Sung ML. Comparison of morphine and alfentanil. Anesth Analg 1985; 64: alfentanil with fentanyl for outpatient anesthesia. 807–810. Anesthesiology 1986; 64: 99–106. 79. Lang E, Kapila A, Shlugman D, Hoke JF, Sebel PS,62. O’Connor M, Sear JW. Sufentanil to supplement Glass PS. Reduction of isoﬂurane minimal alveolar nitrous oxide in oxygen during balanced anaesthesia. concentration by remifentanil. Anesthesiology 1996; 85: Anaesthesia 1988; 43: 749–752. 721–728.63. Mertens MJ, Olofsen E, Engbers FH, Burm AG, 80. Westmoreland CL, Sebel PS, Gropper A. Fentanyl or Bovill JG, Vuyk J. Propofol reduces perioperative remi- alfentanil decreases the minimum alveolar anesthetic fentanil requirements in a synergistic manner: response concentration of isoﬂurane in surgical patients. Anesth surface modeling of perioperative remifentanil–propofol Analg 1994; 78: 23–28. interactions. Anesthesiology 2003; 99: 347–359. 81. Sebel PS, Glass PSA, Fletcher JE, Murphy MR,64. Vuyk J, Mertens MJ, Olofsen E, Burm AG, Bovill JG. Gallagher C, Quill T. Reduction of MAC of desﬂurane Propofol anesthesia and rational opioid selection: with fentanyl. Anesthesiology 1992; 76: 52–59. determination of optimal EC50–EC95 propofol– 82. Hall RI, Murphy MR, Hug CC. The enﬂurane- opioid concentrations that assure adequate anesthesia sparing effect of sufentanil in dogs. Anesthesiology and a rapid return of consciousness. Anesthesiology 1987; 67: 518–525. 1997; 87: 1549–1562. 83. Hall RI, Szlam F, Hug CCJ. The enﬂurane-sparing65. Shafer A, Doze DA, Shafer SL, White PF. Pharmaco- effect of alfentanil in dogs. Anesth Analg 1987; 66: kinetics and pharmacodynamics of propofol infusions 1287–1291. during general anesthesia. Anesthesiology 1988; 69: 84. Wilhelm W, Huppert A, Brun K, Gruness V, 348–356. Larsen R. Remifentanil mit Propofol oder Isoﬂuran.66. Fragen RJ, Fitzgerald PC. Is an infusion pump neces- Ein Vergleich des Aufwachverhaltens bei arthroskopis- sary to safely administer remifentanil? Anesth Analg chen Eingriffen. [Remifentanil with propofol or isoﬂu- 2000; 90: 713–716. rane. A comparison of the recovery times after67. Schwilden H. A general method for calculating the arthroscopic surgery]. Anaesthesist 1997; 46: 335–338. dosage scheme in linear pharmacokinetics. Eur J Clin 85. Grundmann U, Silomon M, Bach F et al. Recovery Pharmacol 1981; 20: 379–386. proﬁle and side effects of remifentanil-based anaesthe-68. White M, Kenny GN. Intravenous propofol anaesthe- sia with desﬂurane or propofol for laparoscopic chole- sia using a computerised infusion system. Anaesthesia cystectomy. Acta Anaesthesiol Scand 2001; 45: 320–326. 1990; 45: 204–209. 86. Eger EI, II, Saidman LJ. Hazards of nitrous oxide69. Chaudhri S, White M, Kenny GN. Induction of anaes- anesthesia in bowel obstruction and pneumothorax. thesia with propofol using a target-controlled infusion Anesthesiology 1965; 26: 61–66. system. Anaesthesia 1992; 47: 551–553. 87. Krogh B, Jørn Jensen P, Henneberg SW, Hole P,70. Sykes MK, Loh L, Seed RF, Kafer ER, Kronborg O. Nitrous oxide does not inﬂuence operat- Chakrabarti NK. The effect of inhalational anaesthet- ing conditions or postoperative course in colonic ics on hypoxic pulmonary vasoconstriction and pul- surgery. Br J Anaesth 1994; 72: 55–57. monary vascular resistance in the perfused lungs of the 88. Taylor E, Feinstein R, White PF, Soper N. Anesthesia dog and cat. Br J Anaesth 1972; 44: 776–788. for laparoscopic cholecystectomy: is nitrous oxide con-71. Mathers J, Benumof JL, Wahrenbrock EA. General traindicated? Anesthesiology 1992; 76: 541–543. anesthetics and regional hypoxic pulmonary vasocon- 89. Steffey EP, Johnson BH, Eger EI. Nitrous oxide striction. Anesthesiology 1977; 46: 111–114. intensiﬁes the pulmonary arterial pressure response
74 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY to venous injection of carbon dioxide in the dog. quantitative systematic review of randomized, placebo- Anesthesiology 1980; 52: 52–55. controlled studies. Br J Anaesth 1999; 83: 761–771. 90. Greville AC, Clements EAF, Erwin DC, 103. Kranke P, Morin AM, Roewer N, Wulf H, Eberhardt McMillan DL, Wellwood JM. Pulmonary air embolism LHJ. The efﬁcacy and safety of transdermal scopol- during laparoscopic laser cholecystectomy. Anaesthesia amine for the prevention of postoperative nausea and 1991; 46: 113–114. vomiting: a quantitative systematic review. Anesth 91. Felts JA, Poler SM, Spitznagel EL. Nitrous oxide, Analg 2002; 95: 133–143. nausea, and vomiting after outpatient gyneco- 104. Liu K, Hsu CC, Chia YY. The effect of dose of dex- logic surgery. J Clin Anaesth 1990; 2: 168–171. amethasone for antiemesis after major gynecological 92. Hovorka J, Korttila K, Erkola O. Nitrous oxide does surgery. Anesth Analg 1999; 89: 1316–1318. increase nausea and vomiting following gynaecologi- 105. Apfel CC, Kranke P, Eberhardt LHJ, Roos IA, cal laparoscopy. Can J Anaesth 1989; 36: 145–148. Roewer N. A comparison of predicting models for 93. Sukhani R, Lurie J, Jabamoni R. Propofol for ambula- postoperative nausea and vomiting. Br J Anaesth tory gynecologic laparoscopy: does omission of 2002; 88: 234–240. nitrous oxide alter postoperative emetic sequelae and 106. Pierre S, Benais H, Pouymayou J. Apfel’s simpliﬁed recovery? Anesth Analg 1994; 78: 831–835. score may favourably predict the risk of postoperative 94. Macario A, Weinger M, Carney S, Kim A. Which nausea and vomiting. Can J Anaesth 2002; 49: 237–242. clinical anesthesia outcomes are important to avoid? 107. Habib AS, Gan TJ. Evidence-based management of The perspective of patients. Anesth Analg 1999; 89: postoperative nausea and vomiting: a review. Can 652–658. J Anaesth 2004; 51: 326–341. 95. Apfel CC, Läärä E, Koivuranta M, Greim CA, 108. Apfel CC, Roewer N. Postoperative Übelkeit und Roewer N. A simpliﬁed risk score for predicting post- Erbrechen [Postoperative nausea and vomiting]. operative nausea and vomiting. Anesthesiology 1999; Anaesthesist 2004; 53: 377–391. 91: 693–700. 109. Penﬁeld AJ. Laparoscopic sterilization under local 96. Cohen MM, Duncan PG, DeBoer DP, Tweed WA. anesthesia. Obstet Gynecol 1977; 49: 725–727. The postoperative interview: assessing risk factors for 110. Burke RK. Spinal anesthesia for laparoscopy. A nausea and vomiting. Anesth Analg 1994; 78: 7–16. review of 1063 cases. J Reprod Med 1978; 21: 59–62. 97. Koivuranta M, Läärä E, Snare L, Alahuhta S. A sur- 111. Ferzli GS, Dysarz FA. Extraperitoneal endoscopic vey of postoperative nausea and vomiting. Anaesthesia inguinal herniorrhaphy performed without carbon 1997; 52: 443–449. dioxide insufﬂation. J Laparoendosc Surg 1994; 4: 98. Apfel CC, Kranke P, Katz MH et al. Volatile anaes- 301–304. thetics may be the main cause for early but not 112. Hirschberg T, Olthoff D, Borner P. Vergleichende delayed postoperative nausea and vomiting: a ran- Untersuchungen zur Durchfuhrung der totalen domized controlled trial of factorial design. Br J extraperitonealen Hernioplastik in kombinierter Anaesth 2002; 88: 659–668. Spinal-Epidural-Anästhesie versus balancierter 99. Apfel CC, Korttila K, Abdalla M, Biedler A, Pocock S, Allgemeinanästhesie [Comparative studies of total Roewer N. An international multicenter protocol to extraperitoneal hernioplasty in combined spinal assess the single and combined beneﬁts of antiemetic epidural anesthesia versus balanced general anesthe- strategies in a controlled clinical trial of a 2 ϫ sia]. Anaesthesiol Reanim 2002; 27: 144–151. 2 ϫ 2 ϫ 2 ϫ 2 factorial design (IMPACT). Control 113. Salihoglu Z, Demiroluk S, Yavuz N. Minimally inva- Clin Trial 2003; 24: 736–751. sive preperitoneal inguinal hernia repair with epidural100. Divatia JV, Vaidya JS, Badwe RA, Hawaldar RW. anaesthesia. Anaesth Intens Care 2002; 30: 813–814. Omission of nitrous oxide during anesthesia reduces 114. Gramatica Jr L, Brasesco OE, Mercado Luna A et al. the incidence of postoperative nausea and vomiting. Laparoscopic cholecystectomy performed under A meta-analysis. Anesthesiology 1996; 85: 1055–1062. regional anesthesia in patients with chronic obstructive101. Tramer M, Fuchs-Buder T. Omitting antagonism of pulmonary disease. Surg Endosc 2002; 16: 472–475. neuromuscular block: effect on postoperative nausea 115. Edelman DS. Alternative laparoscopic technique for and vomiting and risk of residual paralysis. A system- cholecystectomy during pregnancy. Surg Endosc 1994; atic review. Br J Anaesth 1999; 82: 379–386. 8: 794–796.102. Henzi I, Walder B, Tramer M. Metoclopramide in the prevention of postoperative nausea and vomiting: a
COMPLICATIONS AND CONTRAINDICATIONS OF LAPAROSCOPIC SURGERY 6Laparoscopic operations carry a distinct risk of com- Gas embolismplications despite their minimal invasiveness, as shownin Table 6.1. In one study, the incidence of typical Intravascular gas embolism is one of the most seriousanaesthesiological complications, such as hypo- or complication of laparoscopic surgery. Depending onhypertension, tachycardia, hypercapnia, dysrhythmia, the gas used for insufﬂation, the speed of entrain-hypoxaemia or hypothermia, in the course of laparo- ment, the volume of gas entering the blood streamscopic cholecystectomy was 19.8% compared to 14.8% and the anaesthetic, the clinical impact of this compli-with open cholecystectomy, but 3.7% with short cation ranges from a virtually inapparent course togynaecological laparoscopic procedures.1 The most death on the table. The incidence and the severity offrequent complication during laparoscopic cholecys- gas embolism also depends on the type of endoscopictectomy was hypotension, which was seen in 13% of operation performed. Besides being aware of the factorsthe patients. Arterial hypertension is a regular occur- that lead to embolization, the anaesthetist must alsorence and most reviews do not even count it as a be well acquainted with those that aggravate the clin-complication. Hypothermia, nausea and vomiting, ical effects of a gas embolism once it has occurred.hypoxaemia and pain head the list of the postopera-tive adverse events (Table 6.2). Subcutaneous emphy- Gas embolism occurs frequently during hysteroscopy,sema, the incidence of which depends on the type of and small amounts of gas can be detected in the rightoperation, is a typical surgical complication of laparo- heart with a precordial Doppler stethoscope in up toscopic operations that can have considerable anaes- 50% of all patients,2 while larger amounts that can bethetic implications in the postoperative period. The auscultated with a normal stethoscope are found inmost important complications will be described and 10–15% of the patients.3 Pressurized air was originallydiscussed in the following chapters. used to dilate the uterus but the unacceptably high incidence of fatal gas embolism triggered a search for a safer insufﬂation gas.2–5 The most important develop- ment towards preventing fatal gas embolisms was the introduction of carbon dioxide (CO2) as insufﬂation Table 6.1 Complications of laparoscopic operations with relevance to anaesthesia gas (see Chapter 2). Other gases, such as oxygen (O2) or helium (He), have been studied for use as insufﬂation Cardiovascular gas, but they offer no advantage over CO2 with regard to Hypotension, hypertension, tachycardia, bradycardia, dysrhythmias Pulmonary Table 6.2 Incidence of adverse postoperative events Hypercapnia, hypoxaemia, atelectasis, barotrauma after laparoscopic cholecystectomy (LC), open chole- Related to gas insufﬂation cystectomy (OC) or gynaecological laparoscopy (GL)1 Subcutaneous emphysema, gas embolism, pneumo- Event LC OC GL thorax, pneumomediastinum, extreme CO2 absorption Surgical All (%) 52.5 58.8 20.0 Haemorrhage, damage to hollow viscera, damage to Hypothermia (%, skin 31.4 11.8 Not nerves temperature Ͻ35°C) studied Mechanical PONV (%) 12.9 16.4 5.7 Damage to nerves or eyes (positioning and draping), Hypoxaemia (%, SO2 10.9 25.9 1.3 dislodgement of endotracheal tube with endobronchial Ͻ90% when breathing intubation room air) Severe pain (%) 4.0 12.9 4.4 Miscellaneous Hypothermia, nausea and vomiting, hyperkalemia, PONV: postoperative nausea and vomiting; SO2: oxygen renal failure saturation.
76 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY 120 100 O2 Increase of MPAP (%) 80 Air N2O 60 40 20 0 0 10 20 30 40 50 60 70 80 90 Injected CO2 volume (ml) Figure 6.2 Increase of MPAP following intravenous injection of CO2 while breathing room air, 100% O2, or N2O:O2 79:21. (Data from Ref .) the high incidence of detectable gas bubbles followingFigure 6.1 Diagram of vascular injury during initial blind the beginning of insufﬂation.14 Intravascular gas insuf-introduction of the trocar. ﬂation occurring intraoperatively can result from the insufﬂation trocar becoming dislodged from an origin- ally correct position.16 Gas can also pool in the venousgas embolism. Quite the contrary, due to their physico- system and cause symptomatic systemic embolizationchemical properties they carry the same risk of fatal after some delay.17 Gas embolism has also beenembolism as air.6 described during the use of gas-cooled laser probes orClinically apparent gas embolism occurs much less ﬂuid dissectors on well-vascularized organs, such asfrequently during laparoscopy than during hyster- the liver.12,18–20oscopy,4,7–13 although the incidence of gas bubbles The only initial effect of a small amount of gas on thedetected in the right heart by echocardiography dur- circulation is an increase of pulmonary artery pres-ing laparoscopic cholecystectomy was almost 70%.14 sure, the magnitude of which depends primarily onAnimal studies have shown that the incidence of gas the type of insufﬂated gas. Injecting 20 ml of air intra-embolism is nearly 100% during laparoscopic dissec- venously increases the mean pulmonary artery pres-tion of the liver.15 The reason for the lower incidence sure (MPAP) in a spontaneous breathing dog by anof clinically relevant embolic events despite the high average of 87%, while the MPAP increase afterprevalence of intracardiac gas bubbles is possibly due injecting the same volume of CO2 is only 10%.21 Ato the lower insufﬂation pressure and the vascular larger volume of gas reduces blood ﬂow in the lung byanatomy. Gas cannot pass directly from the abdominal obstructing pulmonary arteries and blocking rightcavity through the uninjured peritoneum into the ventricular outﬂow.blood stream, and signiﬁcant intravascular entrainmentof gas occurs during laparoscopic cholecystectomy only Nitrous oxide (N2O) intensiﬁes the circulatory effectswhen the insufﬂation needle is incorrectly positioned of a gas embolism, causing smaller intravascular bubblesor when veins are injured that for some reason cannot to acquire clinical relevance. Injecting 20 ml of aircollapse. This happens frequently during the early into a dog breathing a N2O–O2 mixture raises pul-stages of insufﬂation, since the Veress needle is intro- monary artery pressure not by 87% as when breath-duced blindly and the tip can be inserted into a vein ing room air, but by 148%.21 N2O reduces the mediandespite all precautions (Figure 6.1).10 Small peritoneal lethal volume (LD50) of an intravenous injection ofveins can be torn by the trocar during insertion and gas by approximately 60–80%.22 It also magniﬁes theremain open until they are compressed by an increase circulatory effects of intravascular CO2 bubbles andin intra-abdominal pressure (IAP). This would explain intensiﬁes the resulting MPAP increase (Figure 6.2).21
C O M P L I C AT I O N S A N D C O N T R A I N D I C AT I O N S O F L A PA R O S C O P I C S U R G E RY 77 Blood Table 6.3 Symptoms of gas embolism PCO2 713 mmHg • Fall of end-tidal CO2 (increased dead-space PH2O 47 mmHg O2 ventilation) PN2 0 mmHg • Dysrhythmias (bradycardia, ventricular ectopic beats, tachycardia, asystole) CO2 PCO2 40 mmHg • Hypotension (decreased left ventricular ﬁlling) PO2 180 mmHg • Fall in arterial O2 saturation N2 PN2 540 mmHg • Increased CVP and venous congestion(a) • ECG signs of acute right heart strain • Auscultatory phenomena (tympanic second heart sound, mill-wheel murmur) Blood PCO2 713 mmHg PH2O 47 mmHg PCO2 40 mmHg Tricuspid regurgitation can be observed even with PH2O 47 mmHg PN2O 0 mmHg PN2O 673 mmHg otherwise inapparent gas embolism.24 An acute increase CO2 in right ventricular pressure induces typical changes in PCO2 40 mmHg the electrocardiography (ECG), such as tall R-waves N2O PO2 180 mmHg in V1, peaked P-waves best seen in the inferior leads, PN2O 540 mmHg right axis deviation, atrial dysrhythmias and right bun-(b) dle branch block. Left ventricular ﬁlling pressure fallsFigure 6.3 (a) Transformation of a CO2 bubble into a and with it systemic arterial pressure.N2O bubble in blood saturated with N2O. The partial pres- The reduction of pulmonary perfusion increases thesures are given without regard to the hydrostatic pressure extent of the West I zones in the lungs. These are theof the surrounding blood. (b) During ventilation with O2:N2mixture the CO2 bubbles dissolve rapidly, since N2 has areas in which the ventilation–perfusion relationshipa low diffusion coefﬁcient and enters the bubbles more is shifted towards dead-space ventilation. The resultingslowly than CO2 diffuses out. PCO2, PH2O, PN2, PN2O and fall of the capnometric end-tidal CO2 concentration isPO2 are partial pressures of CO2, H2O, N2, N2O and O2, one of the most sensitive indicators of an embolism.respectively. The widespread misconception that the CO2 bubbles trapped in the pulmonary circulation would be exhaled and thereby increase the end-tidal CO2 concentrationThe elevated pressure also returns to normal more is not supported by clinical observations and has beenslowly in the presence of N2O. disproved in animal studies.25Why do entrained CO2 bubbles that dissolve very rap- Acute right ventricular dilation in combination withidly in blood under normal circumstances, cause such inadequate myocardial perfusion predisposes to cardialsevere circulatory problems when N2O is in the inspira- dysrhythmias. Bradycardia followed by tachydysrhyth-tory gas mixture? One has to imagine that in this case mia is frequently the initial manifestation of anthe blood is saturated with poorly soluble but highly embolism, but an immediate onset with tachycardia anddiffusible N2O. N2O diffuses into the CO2 bubbles at ventricular ectopic beats is also observed. Polymorphicapproximately the same rate as CO2 diffuses outward. ectopic beats which rapidly progress to asystole areO2 also diffuses into the bubbles but signiﬁcantly the consequence if the obstruction of the pulmonarymore slowly, since its diffusion coefﬁcient is about circulation persists.30 times less than that of N2O. In quasi equilibrium, Transoesophageal echocardiography (TEE) is thesomewhat smaller bubbles will remain, ﬁlled with most sensitive method for detecting intracardial gas25,26N2O and some CO2 (Figure 6.3). These slowly resolv- followed by Doppler ultrasonography. Gas bubbles caning N2O bubbles remain in the pulmonary circulation be detected in the inferior vena cava and the right heartand are responsible for the clinical symptoms. before they become apparent as acoustical Doppler phenomena or as a fall in end-tidal CO2 partial pressureDetection and symptoms of gas embolism (PetCO2).24 One study showed that auscultation with a precordial or oesophagus stethoscope has a sensitivityThe symptoms of gas embolism (Table 6.3) result from similar to that of capnometry or pulmonary arterythe acute obstruction of the pulmonary circulation, pressure monitoring.25and affect both the arterial and venous systems.23 Asufﬁciently large embolism increases central venous The auscultatory phenomena of venous gas embolismpressure (CVP) and causes signs of venous congestion. depend on the amount of gas trapped in the right
78 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYheart. Small gas bubbles can only be detected by pre- Circulatory complications are then treated followingcordial Doppler ultrasonography as brief swishing the guidelines for cardiopulmonary resuscitation:sounds. A slightly greater amount of gas in the right closed chest cardiac compression, catecholamines forventricle gives a tympanic character to the pulmonic asystole, and deﬁbrillation for ventricular ﬁbrillationcomponent of the second heart sound due to rising or ventricular tachycardia. Inotropes are administeredpulmonary artery pressure, and with increasing gas to support the right ventricle. Vasopressors should bevolume the typical splashing, churning sound reminis- used to treat severe hypotension and to maintain acent of a washing machine, and known as a mill-wheel minimal coronary perfusion.murmur, can be heard. A Doppler stethoscope should Some recommend introducing a central venous catheterbe used as an early warning system for operations with into the right ventricle and aspirating the trapped gas.a high risk of embolism, since this allows prompt coun- One study showed that intracardial gas aspiration wastermeasures to be taken to stop further gas entrainment no more effective in the management of gas embolismand to prevent the accumulation of relevant amounts than proper positioning,39 while others found it to beof gas. Capnometric evidence of embolism has a greater effective when a multioriﬁce catheter was used, butclinical relevance than ultrasonographic phenomena, even then only if the gas had entered the heart via thesince it reﬂects an actual reduction of pulmonary superior vena cava.40,41 If the patient has an indwellingperfusion. central venous catheter, one can attempt to aspirateThere is a certain risk of paradoxical emboliza- gas, but one should not interrupt other measures intion into the systemic circulation through arteriove- order to insert a catheter.nous shunts in the lung or through a patent foramen After the event the patient should be allowed to awakenovale (present in 30% of all adults), particularly rapidly under intensive care monitoring in order towhen pulmonary artery pressure is increased.27 assess the neurological status. One should look forThis can occlude cerebral or coronary arteries caus- symptoms arising from a paradoxical embolization.ing permanent neurological damage or myocardial Hyperbaric O2 therapy may be beneﬁcial in cerebralinfarction.28–30 gas embolism.28,42 Further close monitoring is indi- cated to detect a delayed occurrence of pulmonarySecondary pulmonary failure can occur even after complications.successful management of the initial event.31–33 Thepathogenesis of this is not completely resolved but CO2 embolism usually resolves rapidly, and the patientsinﬂammatory and coagulatory reaction cascades, acti- normally recover without permanent sequelae; how-vated by the endothelial adhesion of leucocytes and ever, this is not always the case.10,13,17 Acute right ven-thrombocytes in the affected vascular bed, are thought tricular decompensation can drastically worsen theto be involved.34–36 prognosis in patients with congestive heart failure and pre-existing elevated pulmonary artery pressure, while coronary artery occlusion can precipitate fatalTherapy of gas embolism myocardial infarction.The therapy of symptomatic pulmonary gas embolismrequires a concerted approach with the goal of allevi- Noteating the clinical symptoms and stabilizing vital func- • Stop gas insufﬂation immediately!tions. At the same time, one has to prevent the further • Increase inspiratory O2 concentration to 100% O2entrainment of gas, and the expansion of gas already and hyperventilatein the circulation. • Position patient head-down, left lateral decubitus (Durant position)On the slightest suspicion of a clinically relevant • Attempt intracardial gas aspiration if central venousembolism, or the occurrence of unexpected, severe catheter is present (but do not waste time trying to insert a catheter)circulatory symptoms, insufﬂation must be stoppedimmediately and the patients’ lungs ventilated with • Give inotropes to support right ventricle100% O2. The patient is brought into a steep head- • Treat severe hypotension with vasopressorsdown, left lateral decubitus position (Durant pos- • Closed chest cardiac compression for asystoleition) under the assumption that this will facilitate theescape of gas from the pulmonary artery and the right Prevention of gas embolismventricular outﬂow tract.37 However, this position isnot unanimously considered to offer any advantage over It is primarily the surgeon’s responsibility to preventthe horizontal supine position.38 gas embolism, since this complication is usually caused
C O M P L I C AT I O N S A N D C O N T R A I N D I C AT I O N S O F L A PA R O S C O P I C S U R G E RY 79by an incorrect position of the insufﬂating needle or and the ﬂanks and occasionally extends to the chesttrocar. It is the responsibility of the anaesthetist to and mediastinum. In isolated cases, it can extend to theundertake everything possible to remove the risk of neck and face, and in some patients the eyes are swollenclinically relevant embolisms, and to minimize the clin- shut (Figure 6.5). Figure 6.6 shows a chest X-ray of aical effects of a pulmonary gas embolism by early detec- patient with fairly extensive subcutaneous emphysema.tion and effective, competent treatment. This includes One can see the gas inclusion in subcutaneous tissue,avoiding the use of N2O, which seriously aggravates in the structure of the pectoral muscle and in the ﬁnethe clinical course of gas embolism.21 line along the right border of the mediastinum. The direct and indirect pathways by which the gas spreads from the peritoneum are shown in Figure 6.7.Subcutaneous emphysema Following hernia repair and retroperitoneal operations, the emphysema can extend to the abdomen, the ﬂanks,Subcutaneous emphysema, gas in the soft tissues of scrotum and thighs. Gas can also travel through thethe subcutis, is a fairly common complication of laparo- retroperitoneal space into the mediastinum and fromscopic surgery. There is a smooth swelling of the skin, there into the neck and face. The anatomical structuresand crepitations; which are felt on palpation. Gas can along which it spreads are shown in Figure 6.8.also collect in the mediastinum or pericardium, where A potentially dangerous situation can arise if theit reveals its presence by the typical Hamman sign, a emphysema affects the soft tissues of the pharynx. Theprecordial crunching, crackling sound that is syn- swelling can be so extensive that the airway is onlychronous with the heart beat. Patients with extensive kept patent by the endotracheal tube and extubationsubcutaneous emphysema eliminate the excess CO2 would lead to acute airway obstruction and suffoca-absorbed from the tissues by breathing deeply at a high tion.43 Faced with extensive cervicofacial subcuta-respiratory rate. This hyperpnoea occasionally gives neous emphysema, the anaesthetist should alwaysthem a quite disturbing feeling of breathlessness, which inspect the pharynx and hypopharynx for swelling.can be alleviated to a certain extent by the careful An air leak should be heard in adults and older childrenadministration of opiates. after the cuff of the endotracheal tube is deﬂated. IfSubcutaneous emphysema can arise from incorrectpositioning or secondary dislodgement of the insuf-ﬂation needle or trocar (Figure 6.4). It can also occurin the course of an endoscopic operation when theperitoneum is breached (such as in transperitoneal her-nia repair or retroperitoneal operations) or wheneverartiﬁcial cavities are formed by gas insufﬂation (suchas during preperitoneal hernia repair, nephrectomy ormediastinal operations). Subcutaneous emphysemaoccurs with such regularity during some operations,that it should not be considered a complication, but atypical event.The subcutaneous emphysema arising during intraperi-toneal, laparoscopic operations involves the abdomen Figure 6.5 Patient with subcutaneous emphysema extending to the neck and face. If the pharynx is affected toFigure 6.4 Gas is insufﬂated subcutaneously from a mal- the same degree there is a risk of airway occlusion when thepositioned trocar. endotracheal tube is removed.
80 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Figure 6.6 Chest X-ray of a patient with subcutaneous emphysema. Gas can be seen as darker layers in the soft tissue of the patient’s right side. A pennate structure is visible on the upper chest extending towards the arms that is caused by gas in the intra- muscular septa in the pectoral muscle. C2 B2 C1 B2 C3 B3 Figure 6.7 Diagram of the path- ways by which the gas spreads. A1: foramen of Bochdalek; A2: foramen of Morgagni; B1: paraoesophageal hiatus; B2: along the bronchi; B3: pneumopericardium; C1: mediastinal B1 A2 pleural conduits; C2: cervical soft tis- A1 sue; C3: subcutaneously from trocar insertion site.pharyngeal swelling prevents a free view of the glottis, 700 ml minϪ1 in patients with extensive emphysema.and if no air ﬂow around the endotracheal tube is This is an increase of total CO2 uptake of more thandetectable after deﬂation of the cuff, the endotracheal 300% over the rate in patients without emphysema.tube should be left in place until the swelling subsides. These patients require ventilatory minute volumesThis usually takes about 2–5 h. 30 l minϪ1 and more to maintain normocapnia. Hyper- capnia has to be tolerated in some patients, since inspi-Subcutaneous emphysema alone can be a risk factor ratory pressures reach 50 mmHg and ventilation cannotfor the patient, since CO2 absorption can rise to over be increased further without risk of barotrauma.44
C O M P L I C AT I O N S A N D C O N T R A I N D I C AT I O N S O F L A PA R O S C O P I C S U R G E RY 81 respiratory insufﬁciency or impending exhaustion. It is Subcutis difﬁcult to deﬁne a reliable limit beyond which invasive Prevertebral space respiratory support is necessary and warranted. Visceral space Maximal breathing capacity is a parameter that can help (Retroperitoneum, Mediastinum, Pharynx) in the preoperative assessment of how likely postopera- tive respiratory support will be required. However, it is based on a very short measuring period, is very depend- Oesophagus ent on patient cooperation, and gives no information on C-7 how long the ventilatory effort can be sustained before the respiratory muscles are exhausted. Trachea Pneumothorax, pneumomediastinum Lungs T-2 Pneumothorax is not a rare occurrence following Trachea laparoscopic operations.45–47 Gas passes from the peri- toneum directly into the pleural space either through Oesophagus preformed channels, or it spreads from the medi- astinum along the bronchi and bronchioles until it T-5 breaks through a weak spot into the thorax (Figure 6.7). Aorta Barotrauma due to excessive airway pressure with alveo-Inferior vena lar rupture and consequent pneumothorax is another cava Pulmonary possibility. artery Sternum Aorta The intraoperative manifestations of a pneumothorax can be an increase in inspiratory pressure, a decrease L-1 of peripheral O2 saturation, or even a drop in arterial Colon pressure and a simultaneous rise of CVP with tension Liver pneumothorax. Differentiating pneumothorax fromInferior vena Pancreas cava gas embolism is crucial.48 Breath sounds are absent or Stomach diminished on one side in pneumothorax but not in gas embolism. Postoperatively, the patients complainFigure 6.8 Sections through the body showing the extent of dyspnoea and have asymmetrical chest excursions.of the retroperitoneal space. Asymptomatic pneumothorax requires no treatment, since the CO2 is rapidly absorbed. End-expiratoryNewer studies show that postoperative absorption of pressure can be initiated or increased to counteract theCO2 from the emphysema is so slow that spontaneous compression of the lung parenchyma.47 Pneumothoraxrespiration is adequate to eliminate it.44 However, there with severe clinical symptoms calls for immediateis the risk that ventilatory reserve might be exhausted in action. The insufﬂated gas should be vented and if thepatients with severe restrictive or obstructive lung dis- symptoms persist, intrathoracic pressure should beease, or respiratory muscle disorders. If such high-risk relieved by drainage, perhaps with insertion of a pleuralpatients develop subcutaneous emphysema, the endo- catheter. If this is adequate to relieve the symptoms,tracheal tube should be left in place as a precautionary the laparoscopic operation can be continued, if not, themeasure. The patients are allowed to breathe sponta- operation should be converted to an open procedure.neously, perhaps with pressure support, and the courseof end-tidal CO2 and respiratory mechanics are moni-tored to determine the necessity for mechanical ven- Cardiac dysrhythmiastilation. If the endotracheal tube has already beenremoved, respiration (frequency, capnometry, blood The incidence of cardiac dysrhythmia during laparo-gases) must be monitored closely. The decision for rein- scopic operations given in the literature ranges fromtubation and assisted ventilation (synchronized inter- 5% to 47%.49–51 This can be a simple bradycardia ormittent mandatory ventilation, SIMV) with pressure tachycardia, but life-threatening dysrhythmias suchsupport, continuous positive airway pressure (CPAP) as polymorphic ventricular ectopic beats, ventricularshould be made liberally and early if there are signs of ﬁbrillation or primary asystole can occur. There are
82 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYcertain associations between the type of dyshyrthmiaand its triggering factors, and each requires its ownpreventive measures. Bradydysrhythmia leading to Perforationasystole is the most common type of arrhythmia.49 Theunderlying cause is an intense vagal stimulus such as Iliac vesselsperitoneal distension during initial insufﬂation or trac-tion on the viscera. Bradydysrhythmia is also an earlysymptom of gas embolism.Tachydysrhythmia and ventricular ectopic beats are nor-mally a sign of sympathetic nervous system activation,which can be due to hypercapnia or hypoxaemia. Theyusually occur later in the course of the operation thanvagally induced dysrhythmias. The impact of CO2 on Figure 6.9 Retroperitoneal haemorrhage. The large retro-the incidence of dysrhythmias is illustrated by the peritoneal vessels (aorta, vena cava, iliac vessels) can be injuredﬁndings that the incidence was reduced from 17% during the introduction of the Veress needle or the trocarsto 4% when N2O replaced CO2 as insufﬂation gas.50 and can cause serious bleeding. The haemorrhage can spreadThe incidence of dysrhythmias is also inﬂuenced in the retroperitoneum without being noticed by the sur-by the choice of anaesthetic. This is illustrated nicely by geon. The anaesthetist is often the ﬁrst to detect the occultthe results of a study which showed that ectopic beats bleeding when it begins to cause circulatory symptoms.occurred at an PetCO2 of 35 mmHg under halothane,but with enﬂurane they did not appear until PetCO2had increased to 50 mmHg.51Prevention and therapy of dysrhythmias during laparo- Injury to internal organsscopic operations depends on avoiding or correctingtriggering factors. Pharmacological interventions The intestines, stomach and urinary bladder can befollow standard therapy guidelines. injured during insertion of the Veress needle. Lifting the abdominal wall while introducing the needle will lower the risk (Figure 6.10). This complication isHaemorrhage more likely if there are adhesions between the hollow viscera and the parietal peritoneum. A puncture of thisIntraoperative haemorrhage is a potentially serious type is unlikely to cause speciﬁc anaesthesiologicalcomplication. Massive bleeding from the cystic artery problems.is frequently the reason for converting a laparoscopiccholecystectomy to an open procedure.52,53 This type Bipolar electrocoagulation is used for intraoperativeof arterial bleeding is obvious and rapidly detected. haemostasis and for tissue dissection. Unipolar elec-Less common, but more serious, are injuries to great trodes can cause thermal damage to intra-abdominalabdominal vessels that may be inﬂicted with the Veress organs including intestinal lesions with perforationsneedle or the trocars at the beginning of the operation.54 that only become apparent postoperatively.55,56The topography of iliac vessels, aorta and vena cavafavour this type of injury. Tissue can move to cover the Perioperative peripheralperforation and the haemorrhage can spread impercep-tibly in the retroperitoneum (Figure 6.9). The surgeon neuropathywill not see any signs of bleeding, but the anaesthetist Perioperative peripheral neuropathy is a problem ofwill be alerted to the problem by the developing any type of surgery under anaesthesia. Precautionaryhaemodynamic instability. The surgeon should be measures are thought to prevent the occurrence, andinformed if the patient exhibits signs of unexpected this has been supported by a recent advisory evenhypovolaemia, and should subject the abdominal cavity though the authors could not identify conclusive evi-to a careful inspection. dence of a causal relationship in every case.57 The pos-Epigastric arteries can be injured during insertion of itions commonly used during laparoscopic operationsthe trocar. The vessels are frequently compressed by have an inherent risk of nerve damage, particularly ofthe trocar, so that bleeding, which can be brisk, does not the brachial plexus and sciatic nerve or peripheralset in until the trocar is removed. This complication can nerves in the arms and legs (Table 6.4).58–61 Thebe detected by inspecting the puncture sites before the steep Trendelenburg and lithotomy positions as welllaparoscope is removed completely. as abduction of the arms predispose to peripheral
C O M P L I C AT I O N S A N D C O N T R A I N D I C AT I O N S O F L A PA R O S C O P I C S U R G E RY 83 Figure 6.10 Hollow viscera can be injured by the blindly inserted Veress needle. The risk can be reduced by lifting the abdominal wall. Table 6.4 Perioperative neuropathies typical of laparoscopic surgery Nerve Cause Prevention Brachial plexus Pressure or tension Position the shoulder pads carefully, on the plexus reduce abduction of the arm Radial nerve Pressure on the upper arm Position arm alongside patient Sciatic nerve Stretching by hyperﬂexion Reduce ﬂexion of the legs in the lithotomy position Peroneal nerve Pressure on head of ﬁbula Carefully pad the knees (lithotomy position) Obturator nerve Surgical damageneuropathy. Abduction during lithotomy is worse than The radial nerve can be damaged by pressure on theﬂexion since it puts more traction on the obturator medial upper arm, for example from the surgeon lean-nerve.62 ing towards the patient’s head for a better view of the true pelvis. The use of a video camera will remove theThe brachial plexus has long been known to be espe- need of the surgeon to lean in this direction, and posi-cially vulnerable in the steep head-down position.63–65 tioning the arms at the patient’s side will avoid thisPressure from the shoulder pads that prevent the type of injury altogether. Sciatic and femoral neu-patient from sliding from the table can damage the ropathy occurs primarily in the lithotomy position.brachial plexus. A medial position of the pads can Delayed appearance of neuropathy or paralysis of thedirectly injure the long thoracic nerve and parts of obturator nerve has been described as a complicationthe plexus causing acute serratus anterior paralysis of pelvic lymphadenectomy.66,67with the typical symptoms of “hod carrier’s palsy”(“Steinträgerlähmung”), while pads positioned too farlaterally injure a different set of nerves by compress- Miscellaneous complicationsing the plexus between the clavicle and the upper ribscausing “rucksack palsy”. Fastening the patient by the Cephalad displacement of the diaphragm and intra-wrists causes plexus damage both by costoclavicular thoracic organs under the inﬂuence of gravity andcompression and as well by traction on upper portions increased IAP causes a shift of the tip of the endo-of the plexus. tracheal tube relative to the trachea. This can cause
84 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYa one-sided intubation with all the associated conse- in animal studies.88,89 It is not clear whether this occursquences.68–74 This complication can be detected by independently or is simply an epiphenomenon asso-auscultation of the lungs after the patient has been ciated with the hypercapnia and respiratory acidosispositioned and the abdomen inﬂated, and treated by frequently observed during pneumoperitoneum. It maycorrecting the position of the endotracheal tube. Access be associated with the observation that the increase into the patient is nearly impossible in a number of IAP causes a reduction of diuresis and creatinine clear-minimally invasive procedures (see Chapter 3), and ance that can progress to frank renal failure in isolatedthe anaesthetist should be aware of the situations, in cases.90–92which endobronchial intubation can occur, and knowwhich signs should be observed with particular dili- The reduction of blood ﬂow in the legs and pelvicgence. An unexplained fall in peripheral O2 saturation, vessels caused by the pneumoperitoneum and reverseincrease of inspiratory pressure or reduction of Trendelenburg position predisposes to deep veinpulmonary compliance should be taken as signs of thrombosis.93 Data are only available from small patientendobronchial intubation until proven otherwise. collectives,94 but hypercoagulability is seen even after these minimally invasive operations.95 PreventiveHypothermia occurs fairly frequently despite the small measures such as low-dose heparin, compression stock-wound and the fact that the patient is almost completely ings, or intraoperative intermittent pneumatic compres-draped and places a considerable burden on the car- sion is indicated in these patients.96diovascular system.75,76 The main cause of hypothermia There is a theoretical risk of intra-abdominal explo-is thought to be the gas insufﬂation, since the tempera- sions when N2O is used for insufﬂation. The dreadfulture drop correlates with the insufﬂated gas volume name of this complication sounds as implausible as(Ϫ0.3° per 50 l gas77) and to a certain extent with the the ballistic organ syndrome,97 but it actually has beentemperature of the insufﬂated gas.78,79 Warming the reported. Although not combustible itself, N2O sup-insufﬂation gas does not prevent the drop in core ports combustion of methane or hydrogen, which aretemperature, but humidifying it does.80,81 The use of produced in the intestinal lumen.98 These gases areheating mats and convective warming can help pre- normally not present in the peritoneum in relevantvent cooling. Using suitable instruments and careful amounts, since they do not diffuse rapidly enoughtechnique helps to avoid gas loss, thus reducing the through the intact intestine.99 However, their concen-volume of insufﬂated gas and the magnitude of heat loss. trations could increase signiﬁcantly if the wall of theNausea and vomiting following laparoscopic surgery intestine were to be breached. Reports of the actualwere found to be frequent in a number of studies,82–84 occurrence of intra-abdominal explosions seem tobut these data are not conﬁrmed by other studies.1 conﬁrm this possibility.100,101The incidence of nausea and vomiting is usually lowerafter a totally intravenous anaesthetic with propofol Complication spectrum ofand an opiate than after inhalational anaesthesia or individual operationsa balanced technique with a volatile anaesthetic,83,85although contradictory data have been published.82 Individual laparoscopic operations are associated withBasal atelectases and pneumonia are seen in 1–2% of speciﬁc risks and complications (Table 6.5). Laparo-the patients following laparoscopic cholecystectomy. scopic hernioplasty and other operations that invade theThis is approximately the same incidence as seen extraperitoneal space (nephrectomy, retroperitonealfollowing the open procedure.86 adrenalectomy, retroperitoneal lymphadenectomy) have an increased risk of massive CO2 absorption with exces-Completely covering the face during the operation pre- sive hypercapnia. The minute ventilation required todisposes the patient to mechanical damage to the eyes. maintain normocapnia can exceed 30 l minϪ1, and per-The danger is enhanced if the surgeon leans on the missive hypercapnia should be considered in patientshead. An arm support will obstruct direct access to with pre-existing lung pathology.the patient’s head and face, but will prevent pressuredamage to the eyes (see Chapter 3). The eyes should be During laparoscopic operations performed in a steeptaped shut with non-irritating adhesive tape or pro- Trendelenburg position (e.g. hernioplasty, gynaeco-tected with disposable goggles. The use of salve is not logical operations, operations on rectum and sigmoidrecommended since it does not offer any better protec- colon) the tip of the endotracheal tube can migrate totion and can cause corneal oedema and conjunctivitis.87 an endobronchial position and cause hypoxaemia. The lungs should be auscultated frequently to detectThere are isolated reports that pneumoperitoneum this, and the endotracheal tube should be retracted, ifcan cause hyperkalaemia, which have been conﬁrmed it should occur.
C O M P L I C AT I O N S A N D C O N T R A I N D I C AT I O N S O F L A PA R O S C O P I C S U R G E RY 85 Table 6.5 Complications and risks of individual laparoscopic operations relevant to anaesthesia Operation Complications and risks Cholecystectomy Bleeding from the cystic artery, bile leakage Hernioplasty Massive CO2 absorption, hypercapnia, facial and pharyngeal subcutaneous emphysema, endotracheal tube migration to endobronchial position causing hypoxaemia Retroperitoneal procedures Massive CO2 absorption, hypercapnia (lymphadenectomy, adrenalectomy, etc.) Gynaecological operations, rectum, Endotracheal tube can migrate to endobronchial position sigmoid colon operations causing hypoxaemia Adrenalectomy for hyperaldosteronism Hypertensive reaction to surgical stimulation, postural (Conn syndrome) hypotension after positioning with legs lowered Fundoplication Pneumothorax, tension pneumothorax, pneumomediastinum, facial and pharyngeal subcutaneous empysema Surgery of liver and spleen Haemorrhage from organ or supplying vessels. Gas embolism when gas-cooled laser is used for hepatic surgery Table 6.6 Adverse events that can necessitate terminating the laparoscopic operation Complication How to proceed Gas embolism with severe Stop insufﬂation, check for gas entry site, reinsert trocars, careful circulatory symptoms resumption of insufﬂation, convert or terminate if symptoms recur Tension pneumothorax Stop insufﬂation, ventilate with positive end-expiratory pressure, drain pleura if necessary. If the symptoms recur with insufﬂation convert to open procedure or continue with suction on pleural drainage Excessive CO2 absorption Stop insufﬂation, convert to other methodLaparoscopic adrenalectomy for Conn syndrome is the mediastinum and cause facial and hypopharyngealcomplicated by the arterial hypertension and relative subcutaneous emphysema. This is also a typicalvolume depletion in these patients. Hypotension complication of extraperitoneal gas insufﬂation duringoccurs due to venous pooling in the dependent legs, laparoscopic hernioplasty.and adequate ﬂuid substitution with crystalloid solu-tions is required. The patients have a relative ﬂuid Surgery of the liver and spleen can cause appreciableoverload when they are returned to a level supine pos- blood loss, and haemorrhage can be so brisk as to inter-ition and this ﬂuid must be removed from the circula- fere with the operation. Lasers are used for coagula-tion postoperatively. Surgical stimulation can cause an tion during liver surgery. Some of these are gas cooledexaggerated blood pressure response that frequently and can cause severe gas embolism.does not respond to deepening the anaesthetic. Beta-adrenergic blockers and nitroglycerine are effective incontrolling this hypertension. Criteria for aborting thePneumothorax and pneumomediastinum can occur laparoscopic procedureduring laparoscopic fundoplication. An open commu-nication between the peritoneum and the pleural cavity There are a number of complications that will forcecompresses the lungs, but this can be compensated for the conversion to an open procedure or even requireby increasing end-expiratory pressure and decreasing premature termination of laparoscopic operationsintra-abdominal inﬂation pressure. Tension pneumo- (Table 6.6). Most of these are surgical complicationsthorax occurs when gas enters the thorax from the and only peripherally involve the anaesthetist. Amongperitoneum by a valve mechanism. It can be severe these are haemorrhage, extensive adhesions, lack ofenough to require draining. Pneumomediastinum is orientation in the operation site, and damage to anatom-usually innocuous itself, but gas can pass through ical structures.52,67,102–105
86 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYThe most important non-surgical complications are gas cardiopulmonary changes induced by the pneumoperi-embolism, tension pneumothorax and extremely high toneum were thought to carry too high a risk. Nowdegree of CO2 absorption. In every case, gas insufﬂa- they are the method of choice, even, or especially, fortion has to be stopped immediately and IAP vented. the extremely obese patient. It is generally recognizedThis is frequently sufﬁcient to allay the symptoms. In that while the intraoperative course might indeed becases of gas embolism, insufﬂation can usually be care- quite tempestuous, the postoperative recovery periodfully recommenced when the circulation is stabilized, is usually much shorter and passes with fewer com-the gas entry site has been identiﬁed and dealt with, and plications than after conventional open procedures.the trocars have been repositioned. In cases of tension Therefore, when determining if one should performpneumothorax, the most important initial measure is to a laparoscopic operation on a patient, one must con-relieve intrathoracic pressure. If the symptoms recede sider not only the risk of the laparoscopic operation,rapidly, insufﬂation can be re-instituted carefully. If the but also compare it to the risks associated with thesymptoms reappear the laparoscopic procedure has to conventional technique – even high risks are accept-be terminated or, if this is not possible or feasible, it can able if the risks of the alternatives are greater. Thebe continued after a chest tube has been placed to pre- postoperative course must be taken into considerationvent intrathoracic pressure build-up. as well. A typical illustration of this is the divergent behaviour of intraoperative complications and post-Insufﬂation should be stopped if CO2 absorption operative advantages of laparoscopic cholecystectomy.signiﬁcantly exceeds the ventilatory capacity of the The pneumoperitoneum and extreme reverse Trende-lungs to deal with it. The gas is usually absorbed from lenburg position of the laparoscopic procedure causean extensive subcutaneous emphysema that normally considerable intraoperative cardiovascular problems,cannot be drained. Our studies have shown that but the better postoperative pulmonary function, moreabsorption decreases rapidly once insufﬂation has been rapid recovery and earlier mobilization comparedterminated.44 However, since it cannot be excluded with the open operation more than makes up for this.that absorption will increase again once insufﬂation isrecommenced, it is probably best to convert to an open Patients with severe cardiovascular or pulmonarytechnique, if possible, or, if not, to use a markedly diseases are commonly described in the literature asreduced inﬂation pressure. absolutely unsuited for elective laparoscopic opera- tions. Pneumoperitoneum does increase circulatory afterload, reduce preload, and interfere with ventila-Contraindications tion of the lungs to an extent which may exceed the adaptive capacity of these patients. But co-existingThe list of contraindications for laparoscopic surgery diseases of this severity are probably contraindica-is in continuous ﬂux (Table 6.7). Not too long ago tions for any kind of elective surgery. However, onemorbid obesity was considered an absolute contra- should not simply regard them as a contraindicationindication for laparoscopic procedures, since the to every vitally indicated operation, but should ﬁrst Table 6.7 Anaesthesiological contraindications for laparoscopic surgery Condition Assessment Congestive heart disease No contraindication for vitally indicated laparoscopic cholecystectomy or other (NYHA II–IV) intra-abdominal operations. Probably contraindication for laparoscopic hernia repair Ischaemic heart disease No contraindication for laparoscopic cholecystectomy or other intra-abdominal operations with adequate monitoring Obstructive and restrictive No contraindication for laparoscopic cholecystectomy or other intra-abdominal pulmonary diseases operations with low risk of excessive CO2 absorption. Relative contraindication for laparoscopic hernia repair or other extraperitoneal operations Morbid obesity No contraindication for most intra-abdominal operations. Caution required for procedures in Trendelenburg position. Pregnancy No contraindication Patent foramen ovale Risk of paradoxical embolization. Relative contraindication for laparoscopic operations Right-to-left shunt High risk of paradoxical embolization. Contraindication for laparoscopic operations NYHA: New York Health Association.
C O M P L I C AT I O N S A N D C O N T R A I N D I C AT I O N S O F L A PA R O S C O P I C S U R G E RY 87consider the perioperative complications and risks uneventful during surgery if care is taken not toassociated with the surgical alternatives. Studies have injure the uterus or its blood supply.111–117 Fetal deathalso shown that high-risk (American Society of has been reported when gas is insufﬂated into theAnesthesiology, (ASA) II–III) patients with predom- uterus. Pneumoperitoneum and hypercapnia reduceinantly congestive heart failure tolerate the circulatory uterine blood ﬂow.118,119 Inﬂation pressure should beload induced by the pneumoperitoneum astonishingly kept to a minimum and hypercapnia should be avoidedwell106,107 and thus should be able to undergo laparo- by adapting ventilation to changes in end-tidal CO2.scopic surgery with careful monitoring and manage- Although surgery is generally not advisable duringment. Even patients with heart transplants tolerate pregnancy, should it become necessary all availablelaparoscopic surgery well.108 The decision will be more data suggest that for most operations the laparoscopicdifﬁcult in patients with manifest congestive heart approach has no more risk for mother and foetus thanfailure who need emergency surgery, but even in these the conventional method. The choice is therefore upcases there probably is no absolute contraindication to the surgeon and the mother.for the laparoscopic technique. Morbidly obese patients have a tendency to developAn example for the opposite case is hernia repair. The hypoxaemia when breathing spontaneously in a supineconventional Lichtenstein operation for tension-free position. Arterial O2 desaturation is even observedmesh repair of inguinal hernias is minimally invasive during mechanical ventilation with 100% O2.120–122and can be performed under local anaesthesia while The degree of hypoxaemia is increased by the pneu-the laparoscopic procedure requires general anaesthe- moperitoneum and the Trendelenburg position, butsia. However, the laparoscopic approach is considered is somewhat, albeit not reliably reduced if the patientby many to offer so many advantages over the conven- is in a head-up position as for upper abdominal pro-tional operation that they outweigh the associated cedures.123,124 On the other hand, obese patients haveintraoperative risks.109 Other studies ﬁnd the exact a very high risk of postoperative pulmonary compli-opposite: patients in the laparoscopic operation group cations after conventional surgery, particularly upperwere discharged and returned to work earlier, but com- abdominal operations.125 This is reduced after laparo-plication rates and the incidence of recurrence were scopic surgery.126 In view of these changes, the laparo-higher.110 All things considered, severe concomitant scopic approach is deﬁnitely indicated in the morbidlycardiopulmonary disease should be regarded as a con- obese patient for upper abdominal operations. Thetraindication for laparoscopic hernia repair. indication for lower abdominal and pelvic surgery is not that easy to decide and depends on the operationSigniﬁcant impairment of pulmonary function is a itself and the perioperative risks associated with thecontraindication for all laparoscopic operations that conventional technique.have the risk of extensive CO2 absorption. In these Patients with a patent foramen ovale are at risk of arter-patients, ventilation can probably not be increased to ial embolization with gas bubbles or debris (see above).the degree required to eliminate the excess CO2 and Some authors therefore suggest avoiding laparoscopicto prevent intraoperative hypercapnia and respiratory surgery in these patients, and this caution is sup-acidosis with their associated complications. Among ported by reports of paradoxical embolism.127 On thethese are nearly all extraperitoneal procedures such as other hand, considering that a substantial percentageretroperitoneal lymphadenectomy, and extraperitoneal of the population actually has a patent foramen ovale,hernioplasty. The decision is more difﬁcult in the case the incidence of this complication in laparoscopicof hiatus hernia repair or nephrectomy, since the post- surgery is rare. However, patients with an intracardialoperative respiratory impairment and the incidence of right-to-left shunt are at a much higher risk for para-pulmonary complications after conventional surgery doxical embolism and should therefore be consideredis signiﬁcant. Laparoscopic cholecystectomy is the ineligible for laparoscopic surgery.method of choice for patients with signiﬁcant respira-tory disease, since functional residual capacity is lessimpaired and the duration of hypoxaemia is much Referencesshorter than after the open procedure. 1. Rose DK, Cohen MM, Soutter DI. LaparoscopicPregnancy is often listed as a contraindication for cholecystectomy: the anaesthetist’s point of view. Canlaparoscopic surgery. This is probably based on J Anaesth 1992; 39: 809–815.subconscious wariness and perhaps also on the fear of 2. Crozier TA, Luger A, Dravecz M et al. Gasembolielitigation should the child eventually has any sort of und Kreislaufstillstand bei Hysteroskopien: Fallberichtedevelopmental difﬁculties. Nearly all reports in the von drei Patientinnen [Gas embolism with cardiac arrestliterature show that laparoscopic surgery is completely during hysteroscopy. A case report on 3 patients].
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Ubhi SS, Maddern GJ. Humidiﬁed gas prevents 95. Caprini JA, Arcelus JI, Laubach M et al. Postoperative hypothermia induced by laparoscopic insufﬂation: a hypercoagulability and deep-vein thrombosis after randomized controlled study in a pig model. Surg laparoscopic cholecystectomy. Surg Endosc 1995; 9: Endosc 1999; 13: 101–105. 304–309.81. Nelskyla K, Yli-Hankala A, Sjoberg J, Korhonen I, 96. Millard JA, Hill BB, Cook PS, Fenoglio ME, Korttila K. Warming of insufﬂation gas during laparo- Stahlgren LH. Intermittent sequential pneumatic scopic hysterectomy: effect on body temperature and compression in prevention of venous stasis associated the autonomic nervous system. Acta Anaesthesiol Scand with pneumoperitoneum during laparoscopic chole- 1999; 43: 974–978. cystectomy. Arch Surg 1993; 128: 914–918.82. Blobner M, Schneck HJ, Felber AR, Goegler S, 97. Barry M. The ballistic organ syndrome. In: Vandermeer J, Feussner H, Jelen-Esselborn S. 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C O M P L I C AT I O N S A N D C O N T R A I N D I C AT I O N S O F L A PA R O S C O P I C S U R G E RY 91100. Drummond GB, Scott DB. Laparoscopy explosion 116. Reedy MB, Kallen B, Kuehl TJ. Laparoscopy during hazards with nitrous oxide. Br Med J 1976; 1: 586. pregnancy: a study of ﬁve fetal outcome parameters101. El-Kady AA, Abd-El-Razek M. Intraperitoneal explo- with use of the Swedish Health Registry. Am J Obstet sion during female sterilization by laparoscopic elec- Gynecol 1997; 177: 673–679. trocoagulation. Int J Gynaecol Obstet 1976; 14: 487–488. 117. Curet MJ, Allen D, Josloff RK et al. Laparoscopy102. Lee VS, Chari RS, Cucchiaro G, Meyers WC. during pregnancy. Arch Surg 1996; 131: 546–550. Complications of laparoscopic cholecystectomy. Am J 118. Walker AM, Oakes GK, Ehrenkranz R, McLaughlin M, Surg 1993; 165: 527–532. Chez RA. Effects of hypercapnia on uterine and103. Siewert JR, Feussner H, Scherer MA, Brune IB. umbilical circulations in conscious pregnant sheep. Fehler und Gefahren der laparoskopischen Cholecys- J Appl Physiol 1976; 41: 727–733. tektomie [Errors and danger in laparoscopic chole- 119. Southerland LC, Cruz AM, Duke T, Ferguson JG, cystectomy]. Chirurg 1993; 64: 221–229. Crone LA. Intraabdominal CO2-insufﬂation in the104. Wolfe BM, Gardiner BN, Leary BF, Frey CF. Endo- pregnant ewe: uterine blood ﬂow, intraamniotic pres- scopic cholecystectomy. An analysis of complications. sure and cardiopulmonary effects. Can J Anaesth 1995; Arch Surg 1991; 126: 1192–1196. 42(Suppl): A21A.105. Tabboush ZS. When hypotension during laparoscopic 120. Santesson J. Oxygen transport and venous admixture in cholecystectomy indicates termination of the the extremely obese. Inﬂuence of anaesthesia and artiﬁ- laparoscopy. Anesth Analg 1994; 79: 195–196. cial ventilation with and without positive endexpiratory106. Safran D, Sgambati S, Orlando III R. Laparoscopy in pressure. Acta Anaesthesiol Scand 1976; 20: 387–392. high-risk cardiac patients. Surg Gynec Obstet 1993; 176: 121. Hedenstierna G, Santesson J, Norlander O. Airway 548–554. closure and distribution of inspired gas in the extremely107. Zollinger A, Krayer S, Singer T et al. Haemodynamic obese, breathing spontaneously and during anaesthesia effects of pneumoperitoneum in elderly patients with with intermittent positive pressure ventilation. Acta an increased cardiac risk. Eur J Anaesth 1997; 14: Anaesthesiol Scand 1976; 20: 334–342. 266–275. 122. Peters J, Steinhoff H. Anaesthesieprobleme bei108. Joshi GP, Hein HA, Ramsay MA, Foreman ML. extremer Fettsucht [Anaesthesiological problems in Hemodynamic response to anesthesia and pneumoperi- extreme adipositas]. Anaesthesist 1983; 32: 324–327. toneum in orthotopic cardiac transplant recipients. 123. Vaughan RW, Bauer S, Wise L. Effect of position Anesthesiology 1996; 85: 929–933. (semirecumbent versus supine) on postoperative oxy-109. Memon MA, Cooper NJ, Memon B, Memon MI, genation in markedly obese patients. Anesth Analg 1976; Abrams KR. Meta-analysis of randomized clinical trials 55: 37–40. comparing open and laparoscopic inguinal hernia 124. Casati A, Comotti L, Tommasino C et al. Effects of repair. Br J Surg 2003; 90: 1479–1492. pneumoperitoneum and reverse Trendelenburg pos-110. Neumayer L, Giobbie-Hurder A, Jonasson O et al. ition on cardiopulmonary function in morbidly obese Open mesh versus laparoscopic mesh repair of inguinal patients receiving laparoscopic gastric banding. Eur J hernia. N Engl J Med 2004; 350: 1819–1827. Anaesthesiol 2000; 17: 300–305.111. Elerding SC. Laparoscopic cholecystectomy in preg- 125. Eichenberger A, Proietti S, Wicky S et al. Morbid nancy. Am J Surg 1993; 165: 625–627. obesity and postoperative pulmonary atelectasis: an112. Schorr RT. Laparoscopic cholecystectomy and preg- underestimated problem. Anesth Analg 2002; 95: nancy. J Laparoendosc Surg 1993; 3: 291–293. 1788–1792.113. Rizzo AG. Laparoscopic surgery in pregnancy: long- 126. Nguyen NT, Lee SL, Goldman C et al. Comparison term follow-up. J Laparoendosc Adv Surg Tech A 2003; of pulmonary function and postoperative pain after 13: 11–15. laparoscopic versus open gastric bypass: a random-114. Oelsner G, Stockheim D, Soriano D et al. Pregnancy ized trial. J Am Coll Surg 2001; 192: 469–476. outcome after laparoscopy or laparotomy in pregnancy. 127. Uchida S, Yamamoto M, Masaoka Y, Mikouchi H, J Am Assoc Gynecol Laparosc 2003; 10: 200–204. Nishizaki Y. A case of acute pulmonary embolism and115. Al-Fozan H, Tulandi T. Safety and risks of laparoscopy acute myocardial infarction with suspected paradox- in pregnancy. Curr Opin Obstet Gynecol 2002; 14: ical embolism after laparoscopic surgery. Heart Vessels 375–379. 1999; 14: 197–200.
POST-LAPAROSCOPY PAIN AND PAIN RELIEF 7Patterns and mechanism of men.6 In a survey of patients in our institution, thepost-laparoscopy pain median pain score was 8 VAS points (range 0–64) immediately after laparoscopic cholecystectomy underThe majority of laparoscopic operations are performed total intravenous anaesthesia with propofol–alfentanilas short-stay or even day-care surgery. Although pain and diclofenac as prophylactic analgesic. The pain hadis less severe and of shorter duration than following decreased to 0 VAS points (range 0–26) at the end of theopen procedures (Table 7.1), it can still be sufﬁciently 10-h postoperative observation period (unpublishedintense to prevent early discharge. The pain after data). In all published studies, pain decreased to belowlaparoscopic surgery has a spatial distribution and 15 VAS points by the third postoperative day (Figurecharacter that is so unique that it is often referred to as 7.1). Joris and co-workers described the discordantthe “post-laparoscopic pain syndrome”.1,2 Pain arises temporal behaviour of the various types of pain fol-from the trocar insertion sites, the intra-abdominal lowing laparoscopic cholecystectomy.7 Visceral paintrauma and also from the rapid distension of the peri- was predominant during the ﬁrst 24 h, but this abatedtoneum with traumatic traction on blood vessels and and was superseded in signiﬁcance by shoulder painnerves, irritation of the phrenic nerve and release of on the following day.inﬂammatory mediators (see reviews in Refs [3,4]). Pain localized in the tip of the shoulder, usually on theThe pain presents as parietal pain in the insertion right side, and the back are typical for laparoscopy.sites, visceral pain from the intra-abdominal wound This is accompanied by visceral upper abdominal pain,and the irritated peritoneum, and pain referred to theshoulder tip, a characteristic feature, or to the back.Post-laparoscopic pain is most frequently located in the Table 7.2 Verbal pain score45upper abdomen, independent of the intra-abdominallocalization of the operation site. 0 1 2 3 4 5Pain tops the list of complaints following laparoscopic No Light Moderate Severe Terrible Intolerablesurgery, with up to 96% of the patients complaining of pain pain pain pain pain painpostoperative pain (Table 7.1). It is most intenseimmediately after the operation, but decreases rapidly.In one study, the patients quantiﬁed the initial inten- 70 Troidl et al.sity as 60 on a 100 point visual analogue scale (VAS),5 Ure et al.but it had decreased under therapy to approximately 60 Michaloliakou et al.30 VAS points within 2 h. This is equivalent to a verbal Crozier et al. 50pain score of 2–2.5 on a six-point scale (see Table 7.2). VAS score 40Women consistently reported more intense pain than 30 Table 7.1 Incidence of moderate to severe postopera- 20 tive pain after laparoscopic surgery 10 Author Operation Incidence (%) 0 0 2 4 8 12 24 36 48 60 72 Croziera Cholecystectomy 76 Postoperative (h) Ure6 Cholecystectomy 95 Götz44 Appendectomy 87 Figure 7.1 Time course of pain intensity after laparoscopic Pier8 Cholecystectomy 95 surgery. Mean VAS scores reported in different studies are Michaloliakou5 Cholecystectomy 96 shown. The differences between the various studies reﬂect a unpublished date. the choice of anaesthetic, postoperative pain therapy and differing assessment times.
94 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY 40 LC 35 OC 30Mean VAS scores 25 Shoulder 40% 20 15 Back 21% 10 5 Upper right 0 abdomen 43% OP 1 2 3 Entlassung Postoperative (day) Trocar insertion sites 55%Figure 7.2 Time course of pain intensity after laparoscopicand open cholecystectomy (LC and OC, respectively). Meanvalues of VAS scores are shown (VAS scores) (*P Ͻ 0.01).6 Table 7.3 Studies on pain intensity and analgesic requirements after cholecystectomies and appendec- tomies performed either with the laparoscopic or the conventional open technique Author Pain Analgesic intensity requirements Figure 7.3 Localization of post-laparoscopy pain. Laparoscopic cholecystectomy (LA) Attwood46 LC Ͻ OC nd sites, and the intraperitoneal wound (46% and 36% of Barkun47 LC Ϸ OC LC Ͻ OC patients, respectively; see Figure 7.4). Although most Kunz48 LC Ͻ OC LC Ϸ OC patients have back and shoulder pain, only few (2% Putensen-Himmer49 LC Ϸ OC LC Ͻ OC and 4%, respectively) describe this as severe. Rademaker50 LC Ϸ OC LC Ϸ OC Ure6 LC Ͻ OC LC Ͻ OC The pathogenesis of the characteristic post-laparoscopic Laparoscopic appendectomy (LC) pain syndrome has not been entirely explained. Its local- Attwood51 LA Ͻ OA nd ization in the shoulder and upper abdominal areas Lejus52 LA Ϸ OA LA Ϸ OA suggest subdiaphragmatic, peritoneal irritation. There McAnena53 nd LA Ͻ OA is evidence that the insufﬂation gas is responsible for the Ure54 LA Ϸ OA LA Ϸ OA irritation, since insufﬂation with carbon dioxide pro- OC: open cholecystectomy; OA: open appendectomy; L Ͻ O: duces more severe intraoperative and immediate laparoscopic procedure superior to open procedure; Ϸ: no postoperative pain in awake patients than, for exam- difference detectable between the two techniques; nd: no data. ple, nitrous oxide.11 Only 8% of the patients operated with a gasless abdominal wall lift device complained of postoperative shoulder pain compared with 46%the intensity of which can exceed that of the surgical with pneumoperitoneum.12wound. In a prospective study, about half of thepatients reported pain in the trocar insertion sites, usu- A subphrenic gas bubble, detectable in over 90% ofally in the navel, 43% had pain in the upper right patients and persisting at least 48 h after deﬂation ofabdomen, 40% described pain in the shoulders and the pneumoperitoneum, is thought to contribute toabout 20% complained of pain in the back. The inci- the typical upper abdominal and shoulder pain.1,2,13,14dence of shoulder and upper abdominal pain can, how- Active aspiration of the residual gas at the end of theever, amount to over 80% (Figure 7.3) and is largely operation reduces postoperative pain.14 One popularindependent of the type of laparoscopic operation. The hypothesis is that the retained carbon dioxide causes aincidence is similar after cholecystectomy, appendec- local acidosis in the peritoneal lining which inducestomy and gynaecological operations.8–10 The intensity pain. In a prospective, randomized study, however, noof this pain reaches its maximum on the ﬁrst or second difference was found between insufﬂation with car-postoperative day. The severest pain is localized in the bon dioxide as opposed to argon with regard to theupper right abdomen, followed by the trocar insertion development of post-laparoscopic pain syndrome,1
P O S T - L A PA R O S C O P Y PA I N A N D PA I N R E L I E F 95 laparoscopy or laparoscopic pelvic surgery. Narchi and colleagues report that 80 ml of either 0.5% lidocaine or 0.125% bupivacaine instilled into the abdomen reduced Neck Ͻ 1% analgesic requirements and the severity of shoulder pain but not abdominal pain.15 Similar results were Shoulder 4% reported by Loughney16 and Helvacioglu.17 Some authors reported that intraperitoneal instillation of local Back 2% anaesthetics was ineffective after laparoscopic cholecys- tectomy,7,18,19 but they did not report if the patients had Upper right been tilted head-down to bathe the upper peritoneum. abdomen 36% Schulte-Steinberg and co-workers found no effect of 20 ml bupivacaine 0.25% i.p. but a signiﬁcant reduc-Trocar insertion tion of global postoperative pain by the interpleural site 41% injection of 30 ml bupivacaine 0.25%.20 On the other hand, Labaille and co-workers demonstrated that Diffuse 6% intraperitoneal ropivacaine (20 ml of a 0.25% solu- tion) signiﬁcantly reduced visceral pain and mor- phine consumption.21 Chundrigar and colleagues also reported signiﬁcant pain relief following laparoscopic cholecystectomy when 20 ml bupivacaine 0.25% were applied directly to the gall bladder bed.22 Non-steroidal anti-inﬂammatory drugs (NSAID) have been used in the treatment of post-laparoscopyFigure 7.4 Localization of the severest post-laparoscopy pain under the assumption that peritoneal inﬂamma-pain.6 tion and prostaglandin synthesis are major determin- ants of pain. Numerous studies have been publishedbut on the other hand, no difference was found in comparing a wide variety of substances againstintra-abdominal pH values. placebo as well as against one another. Most studies demonstrated that NSAID were effective in reducing post-laparoscopy pain23–26 but some studies werePain relief unable to demonstrate more effect of the NSAID over placebo. In most of these, pain levels were lowerThe majority of patients require an analgesic after in the treatment group, but the calculated P valueslaparoscopic surgery.5,6 Opioids are effective in redu- were greater than 0.05, indicating that the sample sizecing post-laparoscopic pain, but the adverse effects, might have been too small,27,28 or that the studysuch as nausea, vomiting and sedation, associated with design was faulty. The study drug was frequentlytheir use can delay patient mobilization and discharge given too late to have developed its full effect by thefrom the post-anaesthetic care unit and from the hos- time postoperative pain was assessed. Newer cyclo-pital. Other approaches have therefore been evaluated oxygenase 2 (Cox-2) inhibitors have been shown to beto provide adequate pain relief in patients undergoing effective in reducing post-laparoscopy pain,26 butlaparoscopic surgery. Among these are instillation of their relative efﬁcacy is questioned.29 The topicallocal anaesthetics into the abdominal cavity, topical application of NSAID might even be effective, sinceapplication of local anaesthetics directly under the the use of a piroxicam patch was shown to alleviatediaphragm, inﬁltration of the incision sites and the the shoulder pain of laparoscopic surgery.30prophylactic administration of non-opioid analgesics. Although NSAID provide at least a certain degree ofThe typical localization of post-laparoscopy pain in the pain relief following laparoscopic procedures, someright upper abdomen, regardless of the site of the intra- authors warn against their use, since as potentabdominal wound, and the projection of pain to the inhibitors of prostacyclin synthesis they can reduceassociated head zone in the shoulder, fostered the renal blood ﬂow, which is already compromised by theassumption that peritoneal irritation was the initiating increased abdominal pressure, and ultimately precipi-event, and prompted treatment with intraperitoneal tate renal failure.31 Ketorolac is reported to be particu-local anaesthetics. A number of studies have been larly dangerous in this respect.32 In fact, ketorolac hasreported, but their results are conﬂicting. The most been taken off the market in some countries because ofpositive effects were seen following diagnostic the incidence and severity of its adverse effects.
96 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYImpairment of renal function is much less likely with none of them are very effective for treating referredthe use of acetaminophen (paracetamol) or metamizol pain the shoulder and back. The intraperitoneal(dipyrone). Acetaminophen has been shown to signiﬁ- instillation of local anaesthetics can also be employedcantly reduce opioid requirements after laparoscopic for pain reduction in the immediate postoperativesterilization.33 One gram of intravenous acetamino- period, but prolonged use would require the place-phen was shown to have an analgesic effect equal to ment of a subdiaphragmatic catheter. Inﬁltrating thethat of 10 mg morphine.34 Metamizol was taken off the trocar insertion sites with local anaesthetic affordsmarket in a number of countries, because of an effective pain relief for a few hours.assumed link to blood disorders, such as agranulocyto- Based on these insights, the most efﬁcient pain therapysis. It has since been relicenced in most of Europe, would consist of the preoperative, prophylactic admin-South America and other countries. Its efﬁcacy for the istration of a non-opioid analgesic, perhaps a combin-treatment of acute postoperative pain is well docu- ation of an NSAID with a centrally acting Cox-3mented.35 Both of these substances are thought to inhibitor, the preoperative inﬁltration of the skin inci-modulate pain perception by acting on Cox-3 species sion sites with a local anaesthetic, the instillation of ain the central nervous system,36,37 and not to affect the local anaesthetic into the upper abdomen prior toconstitutive prostagladin synthesis responsible for abdominal closure and the postoperative supplementarymaintaining renal perfusion and gastric mucosal pro- administration of an opioid as rescue medication.tection. These substances also interact with spinal andsupraspinal serotonergic mechanisms to produce theirantinociceptive effects.38,39 Studies have shown that Note Protocol for postoperative pain relief after laparo-these Cox-3 inhibitors and classic NSAID act syner- scopic surgery:gistically in reducing acute postoperative pain.40,41Intravenous opioids are, of course, effective in the • Preoperative administration of a non-opioid anal- gesic (e.g. NSAID, acetaminophen)treatment of post-laparoscopy pain and are the main- • Pre-incisional inﬁltration of trocar insertion sites withstay of rescue analgesia for break-through postopera- local anaesthetic (e.g. bupivacaine 0.25%)tive pain. Oral oxycodone 10 mg given 1 h before • Intraperitoneal instillation of local anaesthetic solu-surgery was shown to effectively reduce postoperative tion before removing trocars (e.g. 40 ml bupivacainepain and analgesic requirements.42 Intrathecal mor- 0.25%, lidocaine 0.5% or ropivacaine 0.25%)phine reduced postoperative morphine consumption • Rescue medication with small doses of an opioid (e.g. morphine)following laparoscopic colorectal surgery.43 • Treat postoperative shivering with clonidine orIt was shown that the postoperative pain following meperidine55laparoscopic–endoscopic operations could be treatedeffectively with non-steroid antiphlogistics, especiallyif these were administered in time – that is, optimallybefore the operation.5,24 This also reﬂects the results Referencesof a randomized, controlled study in our institution(Crozier, unpublished data). 1. Pier A, Benedic M, Mann B, Buck V. Das postla- paroskopische Schmerzsyndrom. 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Chandrasekharan NV, Dai H, Roos KL et al. COX-3, a Intraperitoneal versus interpleural morphine or bupi- cyclooxygenase-1 variant inhibited by acetaminophen vacaine for pain after laparoscopic cholecystectomy. and other analgesic/antipyretic drugs: cloning, struc- Anesthesiology 1995; 82: 634–640. ture, and expression. Proc Natl Acad Sci USA 2002;21. Labaille T, Mazoit JX, Paqueron X, Franco D, 99: 13926–13931. Benhamou D. The clinical efﬁcacy and pharmaco- 37. Schwab JM, Schluesener HJ, Meyermann R, Serhan kinetics of intraperitoneal ropivacaine for laparoscopic CN. COX-3 the enzyme and the concept: steps cholecystectomy. Anesth Analg 2002; 94: 100–105. towards highly specialized pathways and precision22. Chundrigar T, Morris R, Hedges AR, Stamatakis JD. therapeutics? Prostaglandins Leukot Essent Fatty Acids Intraperitoneal bupivacaine for effective pain relief 2003; 69: 339–343.
98 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY38. Bonnefont J, Courade JP, Alloui A, Eschalier A. cholecystectomy. The McGill Gallstone Treatment Mecanisme de l’action antinociceptive du paracetamol. Group. Lancet 1992; 340: 1116–1119. [Antinociceptive mechanism of action of paracetamol]. 48. Kunz R, Orth K, Vogel J et al. Laparoskopische Drugs 2003; 63(Spec No 2): 1–4. Cholezystektomie versus Mini-Lap-Cholezystektomie.39. Courade JP, Chassaing C, Bardin L, Alloui A, Ergebnisse einer prospektiven, randomisierten Studie. Eschalier A. 5-HT receptor subtypes involved in the Chirurg 1992; 63: 291–295. spinal antinociceptive effect of acetaminophen in rats. 49. Putensen-Himmer G, Putensen C, Lammer H, Eur J Pharmacol 2001; 432: 1–7. Lingau W, Aigner F, Benzer H. Comparison of postop-40. Beck DH, Schenk MR, Hagemann K, Doepfner UR, erative respiratory function after laparoscopy or open Kox WJ. The pharmacokinetics and analgesic efﬁcacy laparotomy for cholecystectomy. Anesthesiology 1992; of larger dose rectal acetaminophen (40 mg/kg) in 77: 675–680. adults: a double-blinded, randomized study. Anesth 50. Rademaker BM, Ringers J, Odoom JA, de-Wit LT, Analg 2000; 90: 431–436. Kalkman CJ, Oosting J. Pulmonary function and stress41. Montgomery JE, Sutherland CJ, Kestin IG, Sneyd JR. response after laparoscopic cholecystectomy: compari- Morphine consumption in patients receiving rectal son with subcostal incision and inﬂuence of thoracic paracetamol and diclofenac alone and in combination. epidural analgesia. Anesth Analg 1992; 75: 381–385. Br J Anaesth 1996; 77: 445–447. 51. Attwood SEA, Hill ADK, Murphy PG, Thornton J,42. Reuben SS, Steinberg RB, Maciolek H, Joshi W. Stephans RB. A prospective randomized trial of Preoperative administration of controlled-release oxy- laparoscopic versus open appendectomy. Surgery 1992; codone for the management of pain after ambulatory 112: 497–501. laparoscopic tubal ligation surgery. J Clin Anesth 2002; 52. Lejus C, Plattner V, Baron M, Guillou S, Héloury Y, 14: 223–227. Souron R. Randomized, single-blinded trial of43. Kong SK, Onsiong SM, Chiu WK, Li MK. Use of laparoscopic versus open appendectomy in children. intrathecal morphine for postoperative pain relief after Anesthesiology 1996; 84: 801–806. elective laparoscopic colorectal surgery. Anaesthesia 53. McAnena OJ, Austin O, O’Connel PR, Hedermann WP, 2002; 57: 1168–1173. Gorey TF, Fitzpatrick J. Laparoscopic versus open44. Götz F, Pier A, Bacher C. Die laparoskopische appendectomy: a prospective evaluation. Br J Surg Appendektomie – Alternativtherapie in allen 1992; 79: 818–820. Appendizitisstadien? [Laparoscopic appendectomy – 54. Ure BM, Spangenberger W, Hebebrand D, Eypasch EP, alternative therapy in all stages of appendicitis?]. Troidl H. Laparoscopic surgery in children and ado- Langenbecks Arch Chir Supp II Verh Dtsch Ges Chir; lescents with suspected appendicitis: results of medical 1351–1353. technology assessment. Eur J Pediat Surg 1992; 2:45. Huskisson EC. Measurement of pain. Lancet 1974; II: 336–340. 1127–1131. 55. Kranke P, Eberhardt L, Roewer N, Tramer M. Single-46. Attwood SE, Hill AD, Mealy K, Stephens RB. A dose parenteral pharmacological interventions for the prospective comparison of laparoscopic versus open prevention of postoperative shivering – a quantitative cholecystectomy. Ann R Coll Surg Engl 1992; 74: systematic review of randomized controlled trials. Eur 397–400. J Anaesthesiol 2004; 21(Suppl 32): A37.47. Barkun JS, Barkun AN, Sampalis JS et al. Randomized controlled trial of laparoscopic versus mini
LAPAROSCOPIC BARIATRIC SURGERY 8Bariatrics is the branch of medicine that deals with when the amount of fat tissue is “increased to such anobese patients and their problems, but mainly with extent that physical and mental health are affectedtheir weight itself. The term bariatics comes from the and life expectancy is reduced”.7 But, while theGreek ␤␣ (barys) meaning “heavy” and a deriva- economic, social or psychological impact of excesstive of the word ␣⑀␣ (iatreia) which means “heal- adipose tissue varies widely between individuals,ing”, as in paediatrics and geriatrics. epidemiological studies and actuary tables of life insurance companies can give accurate estimates of itsMorbid obesity used to be a typical relative con- effects on morbidity and mortality, and have led totraindication for laparoscopic surgery. Now it is an generally accepted classiﬁcation systems.indication of its own. The intention of bariatric sur-gery is to enable morbidly obese patients to lose There are two measures commonly used to quantifyweight that they are unable to lose by conservative the degree of obesity. One is based on the concept ofmeans. The procedures used in bariatric surgery are an ideal body weight (IBW), which is derived fromnot simple weight reduction methods, such as lipo- actuary tables that give the body weight associatedsuction, that work by directly removing excess fatty with the lowest overall mortality rate for a giventissue. Bariatric surgery takes a more complex height and gender. IBW is calculated with the follow-approach that modiﬁes the gastrointestinal system in ing formula:such a manner as to make it almost impossible for thepatient to maintain his or her weight at a high level. Male: IBW (kg) ϭ height (cm) Ϫ100Weight reduction surgery has been performed since Female: IBW (kg) ϭ height (cm) Ϫ105the 1960s as a measure of last resort to enable mor- Long-term studies have shown that men whosebidly obese patients to lose weight. Conventional sur- weight was 100–109% of IBW had the lowest mor-gery in these patients is fraught with a wide array tality rates.of potentially lethal complications ranging from pul-monary embolism and pneumonia to poor wound The second, more widely used measure was originallyhealing and wound infection. Laparoscopic tech- described by Quetelet, a Belgian mathematician, inniques are the obvious solution to these problems and 1835 and is now known as the body mass indexhave been used in bariatric surgery since 1993.1,2 The (BMI).9 This is calculated using the followingintraoperative course can be turbulent during laparo- formula:scopic procedures, but recovery is more rapid withfewer complications. Virtually all bariatric operations, weight (kg)even the technically most sophisticated, are now BMI ϭ in kg mϪ2 height (m)2being performed laparoscopically.3–6 The very indica-tion for bariatric surgery is a prime cause of typicalanaesthesiological problems and complications, which where normal range is 18–25 kg mϪ2.the anaesthetist has to anticipate and ultimately deal A person with a BMI of 25–30 kg mϪ2 is consideredwith in this type of laparoscopic surgery. to be overweight, while a BMI over 30 kg mϪ2 deﬁnes obesity.10 Above this level, the nomenclature becomesThe term obesity comes from the Latin word obesitas confusing, since different groups apply the same termthat ultimately derives from the verb obedere, which to different cut-off points.11 Most studies deﬁne mor-means, “to eat away (and get fat)”. It is a condition bid obesity as a BMI over 35 kg mϪ2, but the limit ischaracterized by an excessive accumulation of body sometimes set at 40 kg mϪ2. This, of course, makes itfat. There is no natural dividing line between obesity difﬁcult to compare epidemiological surveys. A BMIand normal weight and no obvious way to grade the over 40 kg mϪ2 is occasionally referred to as severecondition, so that any classiﬁcation will be arbitrary to obesity, and one over 55 kg mϪ2 as super-morbid obes-a certain degree. An operative deﬁnition of obesity ity. For comparison, the BMI of a person 170 cm tallstates that an individual should be considered obese with an ideal weight of 70 kg would be 24 kg mϪ2.
100 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYPrevalence of obesity only 3.5% of all deaths were caused by alcohol. It is likely that obesity has now passed tobacco smoking asObesity has a high prevalence in most of Europe and the main ultimate cause of death in the USA.North America, and this has been increasing steadily Other terms such as severe obesity or super-morbidover the past decades.12 The present incidence of obes- obesity are not unanimously deﬁned, but generallyity (BMI over 30 kg mϪ2) in the USA is between refer to a BMI of more than 40–50 kg mϪ2.20.9% and 30.5% depending on the survey, with theincidence of persons with a BMI over 40 kg mϪ2 Surgery is recommended in patients with a BMI overbetween 2.3% and 4.7%.13,14 This represents an 40, or over 35 if life-threatening co-morbidity is pre-increase of 74% since 1991. sent. To give an idea of what we are talking about: a 165-cm-tall patient with a BMI of 40 kg mϪ2 will weigh 108 kg (5 ft 6 in. tall and 17 stones).The incidence of obesity in Europe exhibits markedgeographical variations. In the UK in 1998, 17.3% of Obesity predisposes to a wide variety of associatedthe men and 21.2% of the women had a BMI of diseases and disease conditions. The most common ofmore than 30 kg mϪ2, and 0.6% of the men and 1.9% these are type II diabetes mellitus, ischaemic heartof the women were classiﬁed as morbidly obese disease, peripheral vascular disease, heart failure,(BMI Ͼ 40 kg mϪ2).15 The incidence of obesity varies hypertension, dyslipidaemia, obstructive sleepeven within a country and between genders. In 1991, apnoea syndrome (OSAS) and cancer (Table 8.2).24–2924.5% of the female residents of former Eastern The relative risk ranges from about three for myocar-Germany were obese as opposed to 18% of Western dial infarction and cancer of the colon up to aboutGerman men.16 The prevalence of obesity in men of eight for diabetes mellitus. These risks are reversibleboth sections of the country increased during the fol- after the patient loses weight.30,31 Aside from theselowing 10 years. During this period, the prevalence of organic diseases, obesity also impinges on economicobesity amongst West German women increased by and social aspects of the individual’s life.6.4%, while there was a 6.3% decrease in the eastern In the UK, reports commissioned by the Nationalhalf of the country. In comparison, in 1991, only 7.0% Health Services (NHS) and the National Institute forof French women and 6.5% of French men were Clinical Excellence (NICE) have demonstrated theobese.17 In 2000, the percentage of the adult French cost effectiveness of bariatric surgery,32,33 showingpopulation with a BMI of more than 30 kg mϪ2 had that it not only brings an increase in the quality-increased to 8.2%.18 adjusted life years for the individual patient, but that it also reduces the societal costs of the co-morbiditiesObesity has an enormous impact on public health, since of obesity. This insight led to the recommendationmorbidity and mortality are greatly increased in per- that this treatment modality be offered to personssons with a BMI over 30 kg mϪ2 (Table 8.1).10,19,20 A suffering from morbid obesity as an aid to weightperson with a BMI over 30 has a 50% higher risk of loss.34,35 A similar American study also found thatdeath than a person with normal body weight, while the providing bariatric surgery to select patient popula-risk is doubled in a person with a BMI over 35.21 Some tions was less costly than ﬁnancing the health costs ofstudies also show an increased risk of death in under- the co-morbidities and was less expensive in the longweight persons.22 In 2000, obesity accounted for nearly run than medical weight reduction programmes.36as many preventable deaths as tobacco smoking in the The generally accepted guidelines on the eligibility ofUSA; 18.1% of all deaths were attributed to smoking patients for bariatric surgery deﬁne the weight-relatedand 16.6% to the effects of obesity.23 In comparison, indication for bariatric surgery as a BMI over 40 kg mϪ2 Table 8.1 Grading of obesity and its associated health Table 8.2 Co-morbidity of obesity risk • Diabetes mellitus type II Classiﬁcation BMI Risk of • Ischaemic heart disease (kg m؊2) early death • Cancer • Hypertension Underweight Ͻ18 Moderate • OSAS Normal weight 18–25 Lowest • Peripheral vascular disease Mild overweight 25–30 Moderate • Psychosocial impairment Obese Ͼ30 Signiﬁcantly increased • Osteoarthrosis Morbid obesity Ͼ35 (40) Very high • Heart failure
B A R I AT R I C S U R G E RY 101(over 35 kg mϪ2, in patients with life-threatening Normalco-morbidities) and failure to lose more than 5–10% ofexcess weight by supervised weight-loss diets, or weightgain after an initial loss. Further criteria are current Lung volume Obese, awakeintensive management in a specialized hospital obesity Closing volumeclinic, an age of 18 years or over, no general contraindi-cations for anaesthesia or surgery, no speciﬁc clinical or Obese, Functional residual anaesthetizedpsychological contraindications for this particular type capacityof surgery and willingness to participate in long-term Residual volumefollow-up.34,37 Patients with behavioural abnormalities,such as signiﬁcant psychiatric disease (e.g. schizo-phrenia), mental retardation, substance abuse, self-destructive behaviour, etc., are excluded from bariatric Figure 8.1 The effect of obesity on FRC. Closure of somesurgery by the National Institute of Health (NIH) small airways occurs at the end of expiration. This increases venous admixture and AaDO2 and causes hypoxaemia. Thisguidelines on the grounds that these abnormalities change is aggravated by induction of general anaesthesia.would probably prevent the patients from complyingwith the postoperative counselling necessary to obtainthe greatest beneﬁt from the operation. wall contributes only slightly to the changes of com-The very nature of the patient selection criteria for pliance and airway resistance caused by increasingbariatric surgical interventions deﬁnes the co-morbidity body weight. The decrease of lung compliance is dueand perioperative complications with which the anaes- in part to the increased pulmonary blood volume,45,46thetist will be dealing in the management of these and partly due to the reduction of FRC with a shiftpatients. Well-founded knowledge is required regarding of the neutral position to a ﬂatter portion of thethe physiological changes of metabolism and drug pressure–volume curve.38disposition resulting from excessive body weight, theconcomitant pathophysiology of the respiratory and The extent of the atelectatic areas seen in the CTcardiovascular systems, and their responses to increased scans increases after induction of anaesthesia in spon-intra-abdominal pressure (IAP) and extreme surgical taneously breathing as well as mechanically ventilatedpositions, and the typical, but serious, postoperative patients,47,48 but this increase is much greater in obesecomplications in order to provide these patients with patients (BMI Ͼ 35 kg mϪ2) than in non-obese patientsthe best possible care. (BMI Ͻ 30 kg mϪ2). The area of roentgenologically detectable atelectasis increases from 2.1% preopera- tively to 7.6% at the end of laparoscopic surgery inPhysiology of obesity the obese vs. from 1.0% to 2.8%, respectively, in the non-obese patients.44 These areas resolve completelyRespiratory system within 24 h in lean patients, but still remain or evenObesity has profound effects on the respiratory increase (to 9.7%) in the obese. The result of thissystem. Functional residual capacity (FRC) decreases along with the reduced FRC is that obese patientswith increasing BMI, falling from approximately have a larger alveolar–arterial oxygen (O2) gradient1.5–2.5 l at a BMI of 20–25 kg mϪ2 to 0.3–0.7 l at a BMI than patients with a normal BMI.38,49 At an inspiredof 40–50 kg mϪ2.38 Expiratory reserve volume and total O2 concentration of 50%, the alveolar–arterial O2 dif-lung capacity are also decreased.39 FRC is reduced to an ference (AaDO2) is 66 mmHg in non-obese patients,extent that it falls below closing capacity (CC) leading while it averages 160 mmHg in the morbidly obeseto small airway closure, ventilation–perfusion mis- (BMI Ͼ 46 kg mϪ2).match, right-to-left shunting and arterial hypoxaemia O2 consumption and carbon dioxide (CO2) productioneven in the awake patient.40–42 Intrapulmonary shunt are increased in the obese individual due to the meta-was found to be 10–25% in the obese as compared to bolic activity of the additional tissue and the increased2–5% in lean control persons.43 The morphological workload.45,50 However, the arterial–venous CO2 dif-correlate of this functional pattern is the signiﬁcantly ference is normal and the metabolic activity related togreater extent of atelectasis seen in thoracic computed body surface area is within normal limits. Increasedtomography (CT) scans in spontaneously breathing, CO2 production requires an increase in alveolar minuteawake obese individuals (Figure 8.1).44 ventilation in order to maintain normocapnia. ThisObesity reduces the compliance and increases the puts an additional strain on the respiratory system andresistance of the total respiratory system.38 The chest increases the O2 cost of breathing.
102 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYOSAS occurs more frequently in obese persons.28 Obese patients require a larger minute ventilation toA long-term consequence of OSAS is the obesity maintain normocapnia49 due to their greater CO2hypoventilation syndrome, an alteration in the control production.of breathing characterized by central apnoeic eventswith an increased reliance on hypoxic drive for venti- Cardiovascular systemlation. The end stage of this is the Pickwickiansyndrome with hypersomnolence, hypoxaemia, hyper- Cardiovascular disorders are common in the obesecapnia, increased pulmonary artery pressure and right population and are a leading cause of morbidity andventricular failure.51 Weight reduction after bariatric mortality. In one survey, 37% of the adult populationsurgery has been shown to improve the sleep apnoea with a BMI over 30 kg mϪ2 also suffered from a cardio-index and arterial blood gases, and to reduce the need vascular disease, while the prevalence was only 10% infor supplemental O2.31 persons with a BMI under 25 kg mϪ2.62 Hypertension is very common in the obese. Factors contributing toAnaesthesia and pneumoperitoneum further aggra- this are sodium retention with expansion of extracellu-vate the poor respiratory situation of the obese lar and intravascular volumes, increase in CO, and thepatient. Induction of anaesthesia reduces FRC by enhancement of the pressor activity of catecholamines50% in the obese patient as opposed to only 20% in and angiotensin II and central sympathetic nervousthe non-obese.52,53 The increased IAP during pneu- system stimulation by the adipocyte-derived proteinmoperitoneum reduces FRC still further.49 After leptin.63–66 Total blood volume is increased, but theinsufﬂation, body position (Trendelenburg or reverse weight-adjusted volume is lower than in lean individ-Trendelenburg) has no signiﬁcant effect on respira- uals (50 ml kgϪ1 in obese vs. 75 ml kgϪ1 in non-obese).67tory mechanics or FRC (Table 8.3).49,54 Some authors CO increases to meet the demands of increased O2recommend ventilation with tidal volumes up to consumption by increasing stroke volume with a con-20 ml kgϪ1 as a method of counteracting the fall in stant ejection fraction. This, combined with theFRC and the subsequent widening of the AaDO2,55,56 increased afterload of hypertension, results in eccentricbut others have shown this to be ineffective or even left ventricular hypertrophy: the ventricle becomes lessdetrimental.57,58 Positive end-expiratory pressure compliant and end-diastolic pressure rises.68(PEEP) ventilation can increase FRC, reduce AaDO2and improve oxygenation in obese patients.59,60 An Obesity is an independent risk factor for ischaemicend-expiratory pressure of 10–12 cmH2O is com- heart disease and sudden death, and co-existingmonly used, but one study showed that a PEEP of hypertension, diabetes mellitus and dyslipidaemia will15 cmH2O increased partial pressure of O2 in arterial compound this problem.25,69,70 The concentration ofblood (PaO2) by ca. 50% from 14.0 to 21.5 kPa high-density lipoprotein (HDL) cholesterol is(FIO2 ϭ 0.5) and reduced the intrapulmonary shunt decreased, while that of low- and very low-densityfraction from 21% to 13%.61 At the same time, car- lipoproteins (LDL and VLDL) is increased. Despitediac output (CO) fell by 20% from 5.5 to 4.4 l minϪ1 this, 40% of the patients with symptoms of angina doso that the net effect was a reduction of O2 delivery, not have demonstrable coronary artery stenosis onsince haemoglobin O2 saturation, the primary deter- catheterization.62 Cardiac dysrhythmias are commonminant of blood O2 content was not altered by the in obese patients, and are the results of increased auto-increase in PaO2. It is, therefore, important to deter- nomic stimulation as well as pathological changes inmine the PEEP level that optimizes pulmonary the cardiac conduction system.69,71,72 The conditionmechanics without impairing CO and O2 delivery, can be aggravated by the hypoxaemia, hypercapnia andand to keep haemoglobin O2 saturation at 98% or myocardial hypertrophy frequently present in obesity.above by adjusting the inspired O2 concentration. Obese patients frequently suffer from an impairment of cardiac function commonly referred to as “obesity- Table 8.3 Respiratory effects of obesity related cardiomyopathy” (Table 8.4). The earlier con- ception that this was a consequence of a fatty • Hypoxaemia inﬁltration of the myocardium has been refuted. The • Reduced FRC sequence of events leading to cardiac dysfunction and, • Ventilation–perfusion mismatch eventually, manifest heart failure are thought to begin • Reduced lung compliance with the increased stroke volume being pumped • OSAS against an elevated afterload. End-diastolic volume • Obesity hypoventilation syndrome increases and the ensuing increased wall tension • Increased minute ventilation (O2 consumption and induces eccentric left ventricular hypertrophy. The CO2 production increased) increased wall thickness of the dilated ventricle is less
B A R I AT R I C S U R G E RY 103compliant and causes impaired diastolic function, Drug distribution and disposition in obesityincreased left ventricular end-diastolic pressure(LVEDP), and insipient interstitial pulmonary Obesity is associated with a number of changes that willoedema.68,73–75 This backward failure of the left ven- have an impact on the distribution, protein binding,tricle tends to chronically elevate pulmonary capillary metabolism and renal elimination of drugs.77 A funda-occlusion pressure, which, together with the increased mental question in anaesthesia for obese patients ispulmonary vascular resistance resulting from hypoxic therefore which drugs are least affected by thesepulmonary vasoconstriction, subjects the right ven- changes, and which body weight – ideal, lean or actual –tricle to an increased workload. The simple change from should be used when calculating the required dose ofa sitting to a supine position increases venous return, intravenous drugs. It is difﬁcult to anticipate the netleft ventricular ﬁlling and CO, but also causes a simul- effect of these changes, and monitoring clinical endtaneous, signiﬁcant rise in pulmonary capillary occlu- points is more important than blindly following calcu-sion pressure and mean pulmonary artery pressure76 lated doses. However, a number of approximations canwhich can precipitate paroxysmal dyspnoea and pul- be made that will help one make a rough estimate of themonary oedema. These patients tolerate rapid increases required dose. An overview of the factors affecting drugof intravascular volume only very poorly. Figure 8.2 disposition is given in Table 8.5.gives a summary of the events leading to “obesity- The volume of distribution is an important factorrelated cardiomyopathy” and cardiac failure. when calculating drug dosages. Factors that will affect this are the increase in adipose tissue, increased lean body mass (LBM), increased intravascular volume Table 8.4 Cardiovascular effects of obesity with a reduction of total body water, altered protein • Intravascular volume increased binding and increased CO. The central volume of dis- • CO increased tribution (VDc), which for practical purposes can be • Systemic and pulmonary hypertension considered identical with intravascular volume, is a • Left and right ventricular hypertrophy determinant of the initially required dose. The • Obesity-related cardiomyopathy absolute value of intravascular volume increases • Reduced exercise tolerance with body weight, but to a lesser extent than weight • Ischaemic heart disease itself.79 Therefore, initial doses should be calculated • Sudden death on the basis of IBW or, more accurately, of LBM.80,81 Obesity OSAS, OHS Oxygen Blood (hypoxaemia, consumption ↑ volume ↑ hypercapnia) Hypoxic Cardiac output ↑ Afterload ↑ pulmonary (stroke volume↑) (hypertension) vasoconstriction LV dilatation andPulmonary artery eccentric hypertrophy hypertension Figure 8.2 Pathogenesis of LV diastolic LV systolic obesity-related cardiomyopa- RV dilatation Ischaemic dysfunction thy and cardiac failure. OHS: dysfunction and hypertrophy heart disease (dp/dtmax ↓) (LVEDP ↑) obesity hypoventilation syn- drome; LV: left ventricle; RV: right ventricle; dp/dtmax: mea- RV LV sure of inotropy; ↑: increase; ↓: failure failure decrease.
104 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Table 8.5 The effect of obesity on determinants of pharmacokinetics Absorption Oral drugs ↔ Unpredictable after intramuscular or subcutaneous administration Distribution Body composition Adipose and lean tissue ↑; VD of lipophilic drugs ↑ Blood volume ↑; VD of hydrophilic drugs slightly ↑ Protein binding Total protein, albumin ↔; free fraction of acidic drugs ↔ Triglycerides, cholesterol, lipoproteins, free fatty acids ↑ causing displacement of acidic drugs and thus raising free fraction ↑78 ␣1-acid glycoprotein ↑; free fraction of basic drugs ↓ Elimination Metabolism Splanchnic blood ﬂow ↑ Phase I reactions ↔↑; Phase II reactions ↑ despite histological and laboratory evidence of hepatic damage Data on drugs with high extraction rate are conﬂicting, but reduction of CO and hepatic blood ﬂow will have large impact on their elimination Excretion Renal blood ﬂow, GFR, tubular secretion ↑; renal clearance ↑ ↑ increased; ↓: decreased; ↔: unchanged. VD: volume of distribution; GFR: glomerular ﬁltration rate. Table 8.6 How to dose intravenous anaesthetics in obese patients Drug Dosed on Comments Propofol IBW, TBW Calculate induction dose with IBW, but maintenance dose with TBW. Systemic clearance and VD correlate well with TBW Thiopental LBM For induction – not used for maintenance Atracurium, TBW Absolute VD unchanged, but higher relative dose does not prolong effect89,90 Cisatracurium Vecuronium, IBW or LBM Little distribution into adipose tissue; pharmacokinetics and pharmacodynamics Rocuronium unaltered in obese patients85,86 Fentanyl, TBW VD correlates with TBW; clearance is unchanged, but effects can be prolonged91,92 Sufentanil Alfentanil LBW, TBW VD is smaller than for sufentanil or fentanyl, but alfentanil still distributes widely into adipose tissues. Effect prolonged after continuous infusion Remifentanil IBW or LBM Small VD, similar in obese and lean patients93 Midazolam TBW Highly lipophilic; VD increases with weight. Prolonged effect after adequate dose84 TBW: total body weight; VD: volume of distribution.LBM is higher than IBW, since approximately lipophilic drugs, on the other hand, such as non-20–40% of an obese individual’s weight gain is due to depolarizing neuromuscular blockers, should still bean increase in lean tissue. dosed on the basis of IBW or LBM.85–87 Succinylcholine and atracurium are exceptions to this rule. PlasmaThe required maintenance dose of a continuously cholinesterase activity increases in proportion to bodyinfused drug depends on its volume of distribution at weight and the dose of succinylcholine should besteady state (VDss), and this depends on its lipid solubil- increased accordingly.88 Despite the lower volume ofity. Due to the absolute increase in adipose tissue, the distribution of atracurium relative to weight, its effect isvolume of distribution of highly lipophilic drugs, such not prolonged when dosed according to total bodyas barbiturates, propofol or benzodiazepines is greatly weight.89,90 Speciﬁc data on cisatracurium is lacking, butincreased in obesity82–84 and maintenance doses should it is virtually indistinguishable from atracurium, and itsbe calculated on the basis of total body weight. Less distribution and metabolism should be similar. Table 8.6
B A R I AT R I C S U R G E RY 105gives an overview of the weight that should be used to Gastric emptyingcalculate the doses of drugs used in anaesthesia. Obese patients are thought to be at a higher risk of aspi-Fentanyl and its congeners are highly lipophilic and ration of gastric contents due to increased IAP, delayedshould thus be dosed according to total body weight, gastric emptying, and an increased incidence of hiatuswith the exception of remifentanil. The volume of hernia and reﬂux. After an 8-h fast, 90% of obesedistribution of fentanyl and sufentanil correlates well patients had a gastric ﬂuid volume of more than 25 mlwith total body weight, and both substances are dis- with a pH of less than 2.5.99 These ﬁgures are generallytributed extensively in fatty as well as lean tissues.91,92 considered to represent a high risk of aspiration pneu-Remifentanil, on the other hand, although also highly monitis should the gastric ﬂuid enter the lungs. Laterlipophilic, has only a small volume of distribution and studies have shown that gastric emptying is actuallyits pharmacokinetics are virtually the same in obese more rapid in obese individuals,100 and that the lowerand lean patients.93 This is due in part to its degrad- oesophageal sphincter is as competent in obese patientsation by ubiquitously present esterases. Alfentanil has without symptomatic gastro-oesophageal reﬂux as ina similar volume of distribution in obese and non- non-obese individuals.101 But since obese patients have aobese individuals, but the elimination half-life is much greater gastric volume to begin with, the residuallonger in obese patients due to its reduced clearance. volume will still be larger than in non-obese individualsThe extent of protein binding will probably differ in despite more rapid emptying. It is therefore sensible toobese patients. Total plasma protein and albumin con- take all precautions against aspiration of gastric con-centrations are the same in lean and obese individuals tents. These include lowering gastric pH with H2 recep-but their binding capacity can be reduced by the tor antagonists and antacids, rapid-sequence inductionhigher concentrations of triglycerides, cholesterol, with cricoid pressure or even awake intubation.free fatty acids and lipoproteins in dyslipidaemia. Thenet effect of this would be higher free fractions of Endocrine disordersacidic drugs. The plasma concentration of ␣1-acid Insulin resistance and hyperinsulinaemia are consist-glycoprotein is elevated in obese patients, and this will ent features of obesity and are directly related todecrease the free fraction of basic drugs. body weight. Type 2 diabetes mellitus (non-insulin-Hepatic drug elimination is usually not affected in dependent diabetes mellitus) is present despite ele-obese patients, despite the fact that histological abnor- vated levels of insulin. This type of diabetes ismalities, such as fatty inﬁltration, parenchymal cell virtually non-existent in individuals with a BMI ofdegeneration and periportal cellular inﬁltration, are less than 22 kg mϪ2. Long-standing diabetes leads tonearly always present. Phase I reactions (dealkylation, peripheral sensory neuropathy and autonomic dys-oxidation, etc.) are generally normal or even slightly function with gastroparesis, instable heart rate andincreased. Phase II metabolism (glucuronidation, sul- silent myocardial infarctions. Autonomic dysfunction,fatation, alkylation, etc.) is consistently increased. The or dysautonomia, predisposes to cardiac dysrhythmiasreduction of CO and hepatic perfusion as caused by and sudden death. Gonadal hormone levels are alteredthe increased IAP during pneumoperitoneum can in both men and women. Testosterone levels aredecrease the elimination of drugs with a high hepatic decreased in men, whereas androgen and/or oestro-extraction rate (e.g. midazolam, sufentanil,94 gen levels may be increased in obese females. Obesityfentanyl,95 methohexital96) and prolong their effects. is associated with an earlier onset of menarche, irregu- lar and anovulatory cycles and an earlier menopause.Renal elimination and clearance of drugs is increasedin obese patients due to an increase in renal blood ﬂowand glomerular ﬁltration rate of up to 40%.97,98 It Laparoscopic bariatricmight be necessary to increase the doses of renally operationsexcreted drugs. Two fundamentally different surgical approaches have been used to help patients control their caloric Effect of obesity on drug distribution intake. One, referred to as restrictive, aims to restrict • Volume of distribution increases with body weight the absolute amount of food the individual can eat for lipophilic drugs (e.g. opioids (except remifentanil), and the other, referred to as malabsorptive, aims at hypnotics) limiting the number of calories that can be absorbed • Volume of distribution does not increase with body from the ingested food. Each approach has its own weight for hydrophilic drugs (e.g. neuromuscular devoted champions, but they are both basically the blockers) same with regard to anaesthesiological management.
106 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYIn the restrictive procedures, most of the stomach is patient can absorb, no matter how much he or sheeither resected or otherwise blocked off, leaving only a eats. This can be achieved by interfering with diges-small pouch of about 15–35 ml. This restricts the tion or by reducing the time available for nutrientamount of food that a patient is able to ingest per unit uptake, or by a combination of the two. In the latter,time. Purely restrictive procedures were formerly the small intestinal ﬂow is divided into a biliary–most commonly performed bariatric operations, making pancreatic conduit and a food conduit that rejoin nearup 95% of all cases. Weight loss after this type of oper- the ileocoecal valve. The malabsorptive procedureation required a high degree of patient compliance with reduces the absorption of nutrients and calories fromdiet guidelines. The operations were not always success- the ingested food by reducing the time left forful, particularly not in patients who were so addicted to complete digestion and uptake.food that they ingested high caloric liquid foods or The current philosophy is to combine a restrictivesweets in order to satisfy their craving. These patients operation with a malabsorptive modiﬁcation of thecan actually gain weight after a restrictive operation. small intestine to obtain the best and longest lastingMalabsorptive procedures are designed to overcome results. The individual procedures are listed in Tablethis shortcoming by limiting the amount of calories a 8.7 and shown schematically in Figure 8.3. Table 8.7 Types of bariatric surgery Restrictive procedures Reduces the size of the stomach and limits the amount of food that can be ingested per unit of time Malabsorptive procedures Splits small intestinal ﬂow and reduces the time available for digestion and uptake Restrictive operations Horizontal gastroplasty Vertical-banded gastroplasty (VBG) SBG with or without adjustable cuff Malabsorptive operations Jejuno-ileal bypass Combined operations Gastric bypass with Roux-en-Y (RNY) BPD with or without DS SBG: silicone-banded gastroplasty; DS: duodenal switch. BPD: Biliopancreatic diversion. A B C Restrictive Horizontal-banded VBG SBG gastroplasty Malabsorptive Jejuno-ileal bypass Combined Gastric bypass BPD BPD Figure 8.3 Schematic diagrams with RNY (without duodenal switch) (with duodenal switch) of various bariatric operations. (For abbreviations see Table 8.7.)
B A R I AT R I C S U R G E RY 107Typical long-term complications of most of these weight reducing operation, but its limitations haveoperations are protein malnutrition and vitamin, iron caused the enthusiasm for it to wane. In this oper-and calcium deﬁciencies. The anaesthetist dealing ation, a circular window is made through both walls ofwith patients who have undergone bariatric surgery the stomach about 10 cm below the oesophageal–may be confronted with the sequelae. Complications gastric junction. From this hole, a vertical row of sur-more speciﬁc for individual procedures are dumping gical staples is applied up to the His’ angle to createsyndrome, gastric outlet obstruction, stoma margin small pouch. A polypropylene mesh band is placedulceration, slipped bands and band-related erosions. through the window around the outlet of the pouch and adjusted to control the size of the outlet and toRestrictive surgical procedures prevent it from stretching.105Restrictive bariatric operations are the least invasive Malabsorptive surgical proceduresof the weight reducing procedures and simply reducethe holding capacity of the stomach. There are a Jejuno-ileal bypassnumber of methods by which this goal can be In the jejuno-ileal bypass procedure, a short length ofachieved, some of which are adjustable or even com- jejunum is anastomosed to the terminal ileum a shortpletely reversible. distance from the ileocoecal valve, either as an end-to- side or end-to-end enteroenterostomy.106 The malab-Gastric banding sorption caused by bypassing such a long stretch of small intestine does indeed induce signiﬁcant weightIn the original silicone gastric banding (SGB) proce- loss and remission of co-morbidities such as diabetesdure, a silicone band was placed around the stomach mellitus. But the procedure has a number of sidedividing it into two portions: a small pouch adjacent effects that ranged from the subjectively unpleasant,to the oesophagus and the rest of the stomach.102 The such as abdominal bloating and arthralgia, to the lifesize of the resulting oriﬁce was determined during threatening. Protein malnutrition is frequent and forsurgery and it regulated how fast ingested food could unknown reasons 5–10% of the patients develop liverleave the pouch. Once the band had been positioned cirrhosis.106–108there was no way to change the connecting passage-way other than with a second operation. Combined surgical proceduresIn a modiﬁcation of the SGB operation an adjustableportion was added to the silicone band to permit Gastric bypass with Roux-en-Ycorrection of the stomal diameter. This portion is The concept of combining a reduction of the gastricconnected to a subcutaneously positioned injection holding capacity with a diversion of the chymus pastreservoir through which it can be inﬂated or deﬂated the duodenum with the purpose of inducing weightto narrow or widen the stoma.2,102,103 loss was introduced by Mason and Ito.109 VariousThe main complications of gastric banding proced- modiﬁcations of the original technique aimed atures are slippage or malposition of the band requir- reducing the complication rate and improving theing repositioning, and gastric erosion and perforation efﬁcacy led to the bariatric procedure currently mostunder the band.104 commonly performed in the US. This is the gastric bypass with Roux-en-Y (RNY), which accounts for approximately 75% of all operations. In this oper-Horizontal-banded gastroplasty ation, a small (ca. 25 ml) pouch is formed from theThis was the original restrictive operation that stomach at the entrance of the oesophagus. Thisbecame possible after the introduction of the surgical blocks off the larger portion of the fundus and thestapler. Three staples were removed from the staple antrum. The small intestine is transected and the dis-cartridge that was used to partition off the stomach tal end is attached to the newly formed gastric pouchjust distal to the oesophageal–gastric junction. This with a narrow (0.7–1.2 cm) gastroenterostomy toleft a small opening through which food was able to form the food conduit. The proximal end of the tran-pass only slowly. This operation is no longer popular. sected small intestine that carries the biliary and pan- creatic secretions is then reconnected to the food conduit with an enteroenterostomy.Vertical-banded gastroplasty Dumping syndrome is the typical complication of gas-The vertical-banded gastroplasty (VBG) was at one tric bypass procedures, and occurs in two phases.time the most popular and most commonly performed Early dumping is a group of abdominal and vasomotor
108 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYsymptoms arising shortly after food ingestion that are the antro-pyloroduodenal pump intact. The duode-triggered by osmotically induced ﬂuid shifts into the num is stapled shut and chymus is diverted from itsintestinal lumen and by the release of vasoactive hor- proximal end through an approximately 250 cm longmones. These symptoms include nausea, vomiting, stretch of terminal ileum. The biliopancreatic divert-diarrhoea, abdominal cramps, ﬂushing and palpita- ing limb of the small intestine is anastomosed to thetions. Late dumping is caused by reactive hypogly- ileal food conduit ca. 100 cm proximal to the ileo-caemia following rapid insulin release. Anaemia is very coecal valve. Proteins have already been largelycommon in patients with gastric bypass of this type, digested by gastric secretions; so that the short com-since the absorption of iron and vitamin B12 is poor. mon alimentary channel interferes primarily with thePoor absorption of calcium may also occur. These digestion and uptake of fats. This technique essen-nutrients will have to be supplemented in the diet or tially eliminates dumping syndrome and stomalgiven parenterally if necessary. Surgical complications ulceration and reduces the severity of protein malnu-include anastomotic leak, deep vein thrombosis, trition and micronutrient deﬁciencies.pulmonary embolism and respiratory failure. Positioning the patient for bariatric surgeryBiliopancreatic diversion Bariatric surgery requires special operating roomThe biliopancreatic diversion (BPD) resembles the (OR) equipment. The gurneys and operating tablesjejuno-ileal bypass in that it limits the time and intes- must be designed to tolerate a load of at least 400 kgtinal surface area available for the absorption of nutri- and should be wider than standard OR equipment toents, but it avoids a number of complications, such as accommodate the added width of the supine, obesehepatic damage, by not defunctionalizing a section of patient. Electrically or hydraulically adjustable tablesthe small intestine. BPD also resembles the RNY pro- are preferable to manually operated ones for manoeuv-cedure in that food and biliopancreatic secretions are ring the patient into the required position. Obeseinitially conducted through separate channels and then patients have the tendency to slip off the operatingrecombined through an enteroenterostomy. The bil- table when it is sharply tilted, and should thereforeiopancreatic division procedure differs from the latter be securely strapped on. Pressure sores and nerveprocedure in that the antrum and part of the fundus injuries are common in these patients, especially inare not simply sealed off, but are actually removed. diabetics, and the danger spots should be carefullyIn the BPD, a limited gastrectomy is performed that padded. Soft pads ﬁlled with tiny beads are availableremoves the antrum and pylorus and closes the proxi- that mould themselves to the patient’s body. Applyingmal end of the duodenum. The resulting small gastric an external vacuum to the bag ﬁxes it in the adaptedpouch signiﬁcantly limits food intake, creating the shape. Gel pads are also available for padding criticalrestrictive component of the procedure. The ileum is pressure points, such as elbows, shoulder blades, heels,transected approximately 250 cm from the ileocoecal back of the head, sacrum, hips, buttocks, etc. Ulnarvalve and the distal portion of the ileum is anasto- neuropathy occurs more frequently in morbidly obesemosed to the gastric pouch to form the food conduit. patients that in the non-obese.113 Sciatic nerve andAn enteroenterostomy connects the distal end of the brachial plexus palsies can also occur and are usuallyremaining small intestine to the distal ileum about caused by keeping the patient in a tilted position,100 cm from the ileocoecal valve. The short remaining either sideways or Trendelenburg, for longer periods.common alimentary channel creates the malabsorp- Nerve injury may still occur in these patients despitetive component of the procedure.110 Although some all efforts at careful positioning and padding. Thiscomplications are avoided, others such as dumping must be pointed out and discussed with the patientsyndrome, marginal ulcers, stoma closures and block- during the preoperative visit.ages still occur. Removing the antrum and part of the For bariatric surgery, the patient is positioned as forfundus and diverting the chymus away from the duo- most other upper abdominal laparoscopic procedures.denum and jejunum also predisposes the patient The patient lies supine, thighs fully abducted andto protein malnutrition and to vitamin B12, iron and slightly ﬂexed in the hips. The surgeon standscalcium deﬁciencies. between the patient’s legs with one assistant on eachIn a modiﬁcation of the BPD known as the duodenal side of the patient and the scrub nurse to the sur-switch,111,112 the antrum and pylorus are not geon’s left. The laparoscopy tower is positioned nearremoved, but instead stomach volume is reduced by a the patient’s right shoulder (for a right-handed sur-parietal gastrectomy along the greater curvature, geon) so that the patient’s right arm lies alongside hiswhich maintains normal digestive function and leaves or her body. The left arm usually remains abducted
B A R I AT R I C S U R G E RY 109and is accessible to the anaesthetist. However, it may The mandatory preoperative electrocardiogrambe adducted and covered according to the custom of (ECG) can show the relatively tall R-wave in V1the hospital or the surgeon’s preference. Venous lines (R у S), right axis deviation, and the ST segmentwill then have to be extended and ﬁtted with three- depression and T-wave inversion in the right to mid-way stopcocks to allow drug administration. precordial leads characteristic of right ventricular hypertension, or the tall R-waves in V5 or V6, the deepDuring the phase in which the surgeon is manipulat- S-waves in V1 together with the ST segment depres-ing the stomach, the table will be tilted into a more or sion and T-wave inversion in left precordial leads thatless steep reversed Trendelburg position. If the pro- point to left ventricular strain. On the other hand, thecedure requires access to the small intestine, the thickness of the intervening tissue may cause lowpatient will then be brought into a Trendelenburg voltage in the precordial leads and thus mask theposition to give easier exposure of the operation site. severity of existing ventricular hypertrophy. Venous status and arterial access sites should be evalu-Anaesthesia ated during the preoperative visit, and the probabil- ity of central venous and arterial cannulationPreoperative considerations discussed with the patient. Peripheral veins may beFor a comprehensive overview on obesity in anaesthe- very difﬁcult to ﬁnd in obese patients and centralsia see the excellent reviews of Adams and Murphy55 venous catheterization, preferably the internal jugularor Ogunnaike et al.114 vein, is recommended. This will allow a more efﬁcient treatment of intraoperative complications as well asHistory and examination ensure better postoperative venous access and avoid repeated venipuncture. Patients with serious cardio-A meticulous and exhaustive history of patients pre- vascular co-morbidity might proﬁt from the place-senting for bariatric surgery is necessary in order to cor- ment and use of a pulmonary artery thermodilutionrectly assess the perioperative risk proﬁle of thesepatients and to determine the invasiveness of monitor-ing required for optimal management. These patientstend to limit their own mobility and even sleep upright What to look for and ask about in obese patientsand will therefore not report episodes of exertional dys-pnoea or angina, paroxysmal nocturnal dyspnoea or • Systemic and pulmonary hypertension: Exertional dyspnoea, additional heart sounds on auscultation,even orthopnoea. Direct questioning is required to signs of strain or axis deviation in the ECG, echo-obtain this information. The patient should be carefully cardiography, have patient walk the ward or climbevaluated for symptoms of signiﬁcant involvement of stairsthe cardiorespiratory system with particular emphasis • Ischaemic heart disease: History of angina pectorison systemic and pulmonary hypertension, signs of left (may be negative), chronic medication, ST changesand/or right ventricular strain or failure, ischaemic in the ECG, heart wall akinesia or hypokinesia inheart disease, gastro-oesophageal reﬂux, diabetic neur- ultrasoundopathy or OSAS. The patient should be asked to walk • Congestive heart failure: Exertional dyspnoea, parox- ysmal nocturnal dyspnoea, orthopnoea, pulmonarythe length of the ward and to lie supine in order to rales on auscultation, reduced ejection fraction indetect reduced exercise tolerance or orthopnoea. echocardiography, have patient walk the ward orAuscultatory signs of heart failure such as crepitant climb stairs, and lie ﬂat in bedrales and additional heart sounds, jugular venous • Gastro-oesophageal reﬂux: History of heart burn, typ- ical self-medication, patient sleeps elevatedengorgement, hepatomegaly and peripheral oedemamay be difﬁcult to detect due to the large amount of • Diabetic neuropathy, including autonomic dysfunction: History, laboratory and medication will revealsubcutaneous tissue. Clinical symptoms of left or right diabetes, ﬁnding neuropathy is more difﬁcult. Valsalvaventricular failure such as exertional dyspnoea and manoeuvre can give evidence of dysautonomiafatigue indicate further evaluation by a cardiologist. • Other pre-existing sensory or motor impairment:Echocardiography, although frequently difﬁcult in History, physical examinationthese patients, can yield important information such as • Sleep apnoea: Likely to be present, often not diag-the tricuspid regurgitation indicative of signiﬁcant pul- nosed, clinical suspicion warrantedmonary hypertension, the eccentric left ventricular • Possible difﬁcult intubation: Evaluate for Mallampati scorehypertrophy indicating incipient failure even thoughventricular function might appear normal, or regional • Difﬁcult venous access: Check vascular status includ- ing neck and feetwall hypokinesia that might indicate ischaemic disease.
110 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYcatheter. This should be discussed with the patient with an infusion of 5% glucose running at a rate ofduring the preoperative work-up. 125 ml hϪ1.Classical risk predictors of difﬁcult intubation, such as Oral benzodiazepines in anxiolytic but not hypnoticthe Mallampati score115 should be noted. One should doses (e.g. 7.5–10 mg midazolam or 5–10 mg diazepam)discuss the possibility with the patient that tracheal are acceptable for premedication. Absorption is unreli-intubation might be difﬁcult and that alternative able after intramuscular or subcutaneous injections, andmethods, such as ﬁbre-optic awake intubation, these routes of administration should be avoided.although somewhat more unpleasant, might provide a Midazolam can be titrated intravenously during thegreater degree of safety. These should be explained to immediate preoperative period to achieve the desiredthe patient in detail. level of anxiolysis. Oral H2-antagonists (e.g. ranitidine or effervescent cimetidine), proton pump inhibitorsThe laboratory work-up will probably reveal signs of (e.g. omeprazole), propulsives (e.g. metoclopramide,hepatic dysfunction, which are usually of no conse- domperidone) and water soluble antacids (e.g. sodiumquence. Cholesterol and triglyceride levels are usually citrate) can be given to reduce gastric volume and acid-elevated, and dyslipidaemia is frequently present. Blood ity, thus reducing the risk of aspiration pneumonitisglucose concentrations are likely to be increased in and minimizing its severity should it occur (see below).the presence of diabetes mellitus. Extremely high glu-cose concentrations indicating poor metabolic controlcould indicate postponing the operation until the dia- Preparing the patient for anaesthesiabetes is adequately treated. Venous cannulae are best placed in the left arm or inOne should discuss with the patient the typical risks an external jugular vein, since the right arm is pos-and possible complications as well as the planned pre- itioned at the patient’s side and covered by the surgicalventive or therapeutic measures on this occasion and drapes. It is usually very difﬁcult to ﬁnd accessiblethis should be documented. veins in obese patients, and one should consider inserting an intravenous catheter into the brachial or internal jugular vein after induction of anaesthesia and What risks and measures should be discussed with to leave it in place for use in the postoperative period, to the patient draw blood and administer intravenous drugs, and to avoid the need of repeated venipuncture. • Difﬁcult intubation: Aspiration of gastric contents with all its consequences, possible dental injuries, The patient’s arms, legs, back and head must be care- possible necessity of awake nasal intubation fully positioned and padded to avoid pressure damage • Respiratory problems: Atelectasis, pneumonia, postop- during surgery. Well-padded shoulder supports are erative respiratory support with endotracheal tube or required in procedures during which the patient will nasal continuous positive airway pressure (CPAP) be brought into the Trendelenburg position. They • Cardiovascular problems: Central venous catheter, pul- must not be too near the neck in order to avoid brachial monary artery catheter, risk of postoperative myocar- dial infarction, cardiac decompensation, death plexus damage. The shoulders and head are positioned • Deep vein thrombosis: Risk of fatal pulmonary on towels or other supports in order to bring the embolism, early mobilization mandatory patient’s chin anterior to the chest (see below). • Pressure sores and nerve damage: Sometimes unavoid- able despite all precautions Choice of anaesthetic regimen and anaesthetic drugs General anaesthesia with endotracheal intubation isConcurrent medication the standard anaesthetic procedure for bariatric sur-There is still some controversy over whether a gery. Mechanical ventilation is absolutely indicatedpatient’s chronic medication should be discontinued since the combined effects of obesity and pneumoperi-or not. In our institution, all medications with few toneum will otherwise lead to hypoventilation andexceptions are continued until the time of surgery. hypoxaemia in the spontaneously breathing obeseWe withhold oral hypoglycaemics on the day of sur- patient. This will increase pulmonary vascular resist-gery and infuse glucose to avoid hypoglycaemia ance and put an additional load on the right ventricleresulting from residual effects. Biguanides are dis- and should thus be avoided. Some authors advocate thecontinued 2–3 days before surgery. Patients under use of a thoracic epidural catheter to supplement thetreatment with insulin are given one-third of their general anaesthetic and to provide postoperative anal-usual morning insulin dose as regular insulin together gesia.116 This is deﬁnitely an option for open bariatric
B A R I AT R I C S U R G E RY 111 Table 8.8 Standard anaesthetic for morbidly obese patients in the University Hospital, Göttingen Preparation Premedication with midazolam 7.5–10 mg per os (orally) or diazepam 10 mg per os Rofecoxib (50 mg) or valdecoxib (40 mg) can be given orally for pre-emptive postoperative analgesia Induction Induction with propofol (2 mg kgϪ1 total body weight) after a bolus dose of remifentanil (1 g kgϪ1 LBM) (alfentanil (20 g kgϪ1) or sufentanil (0.3 g kgϪ1) are used occasionally) Diclofenac (100 mg supplement) if rofecoxib or valdecoxib has not been given Intubation Relaxation with rocuronium (0.6 mg kgϪ1 LBM) Orotracheal intubation with armoured endotracheal tube Endotracheal tube is ﬁxed securely and bilateral breath sounds are rechecked after patient is in Trendelenburg position Maintenance Propofol infused at a rate of 5–6 mg kgϪ1 hϪ1 total body weight or target plasma concentration of 2–2.5 g mlϪ1 if using a TCI pump Or Desﬂurane 3–4% end tidal or isoﬂurane 0.7–1.0% end tidal Remifentanil is infused at an initial rate of 0.2–0.5 g kgϪ1 minϪ1: • If alfentanil is used, the initial rate is 30–40 g kgϪ1 hϪ1 • If sufentanil is used, the initial rate is 0.3–0.5 g kgϪ1 hϪ1 In all cases, the infusion rate of the opioid is increased or decreased as necessary, and as described in the chapter on anaesthesia. Emergence Extubation when patient is fully awake and in semi-recumbent position O2 by mask or nasal prongs until no further risk of hypoxaemia Consider nasal CPAP on third to ﬁfth postoperative night Pain therapy Rofecoxib (50 mg) or valdecoxib (40 mg) given orally with the premedication, or Diclofenac suppository (100 mg) given after induction of anaesthesia Intravenous paracetamol (1000 mg) infused 15 min before the end of surgery. Repeated every 6 h Bolus injections of morphine (2 mg bolus) if requested by the patientprocedures that, likely any upper abdominal operation, low lipid solubility, such as desﬂurane, isoﬂurane orhave a high potential for severe postoperative pain sevoﬂurane (Table 8.8). Propofol is distributed exten-and respiratory impairment.117 However, an epidural sively in the body, and the pharmacokinetics ofcatheter is probably rarely indicated in minimally inva- propofol used as a component of total intravenoussive laparoscopic procedures, since there is much less anaesthesia in the morbidly obese do not differ frominterference with postoperative pulmonary function, those in lean patients.83 However, there was no sign ofatelectasis is less extensive, arterial oxygenation is bet- cumulation, even when the drug was dosed accordingter, and there is less pain compared to the same opera- to total body weight. This makes propofol a suitabletion, gastric bypass with RNY, performed in the choice for the hypnotic component of a balancedconventional, open fashion.118 anaesthetic. A direct comparison of a total intra- venous technique using propofol with inhalationalA balanced anaesthetic is the method of choice for gen- anaesthesia with sevoﬂurane (end-tidal concentrationeral anaesthesia in the morbidly obese. The hypnotics, 1–2%) showed both methods to be similar withanalgesics and muscle relaxants used for the anaes- regard to haemodynamic stability and recovery char-thetic should be chosen on the basis of their pharmaco- acteristics.120 One can avoid overdosing propofol bykinetics, particularly the context-sensitive half-time using a target-controlled infusion (TCI) pump, ide-(see Chapter 5), as well as metabolism and elimination. ally with neuromonitoring of the depth of anaesthe-Remifentanil is the obvious choice for the analgesic sia. There are no studies that show that obese patientscomponent, due to its unique pharmacokinetics and differ from the non-obese with regard to the plasmalack of cumulation. Remifentanil in a dose of 1 g kgϪ1 concentration of propofol required to produce loss ofis as effective as 1 g kgϪ1 fentanyl or 10 g kgϪ1 alfen- consciousness and intraoperative awareness, and atanil in suppressing cardiovascular responses to intu- targeted concentration of 2.0–2.5 g mlϪ1 will bebation in morbidly obese patients.119 It is dosed adequate for the vast majority of the patients.according to lean body weight. Of the volatile anaesthetics, desﬂurane is probably theThe hypnotic component of the balanced anaesthetic agent of choice for use in laparoscopic bariatriccan be either propofol or a volatile anaesthetic with surgery due to its physicochemical properties and its
112 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYconsistently rapid recovery proﬁle.121 Recovery is medium duration of action can be used to advantage.slightly more rapid after 2 h of anaesthesia with We prefer rocuronium for its very rapid onset ofremifentanil–desﬂurane than after remifentanil– action that allows rapid intubation, but atracurium,sevoﬂurane for laparoscopic gastroplasty. The times cisatracurium, vecuronium or even mivacuriumto extubation and orientation were 5.9 and 6.6 min, are suitable. Pancuronium, pipecuronium or evenrespectively, in the desﬂurane group, and 7.9 and tubocurarine would not be optimal choices, but if9.0 min, respectively, in the sevoﬂurane group.122 nothing else is available they can be used. Residual effects of the muscle relaxant should be reversed atEmergence and recovery times were slightly shorter the end of surgery. Succinylcholine should be given toafter a monoanaesthetic with sevoﬂurane than after facilitate intubation if a muscle relaxant with a slowerisoﬂurane in morbidly obese patients.123,124 The time onset is used.to extubation was 6 min in morbidly obese patientsundergoing gastric banding with sevoﬂurane anaes-thesia as compared to 10 min in patients given isoﬂu- Induction of anaesthesiarane.123 Wash-in times are somewhat faster forsevoﬂurane than for isoﬂurane, and the FA/FI ratio Anaesthesia should be induced with an intravenouswas higher in the patients given sevoﬂurane during hypnotic and not by inhalation, since there is a higherthe ﬁrst 30 min.125 This is of no great import, since incidence of gastro-oesophageal reﬂux in obesethe required alveolar concentration can be achieved patients, and this is a risk factor for regurgitation andjust as rapidly with isoﬂurane by simply increasing aspiration of gastric contents. In fact, one should con-the inspiratory concentration. Wash-out of sevoﬂu- sider using a rapid-sequence induction regimen inrane was signiﬁcantly faster than that of isoﬂurane obese patients. Some authors, reluctant to abandonduring the ﬁrst 60 s after discontinuation of the their tried ways, recommend inhalational inductioninhalational agent. On the other hand, isoﬂurane with sevoﬂurane with the patient in a lateral decubitusmaintains splanchnic blood ﬂow better than does position in order to avoid aspiration of gastric contentsevoﬂurane, and this might be a more important should he or she regurgitate or vomit.128 While thisaspect in laparoscopic surgery than a gain of a few method is obviously possible, mechanics argues againstminutes after several hours of surgery. Halothane it: positioning awake, obese patients on their sides on ashould probably be avoided altogether because of its narrow operating table is no mean feat, while repos-high lipid solubility with slow recovery, and also itioning them on their back again once anaesthesia hasbecause obesity is possibly a risk factor for halothane- been induced is positively daunting.induced hepatic injury.126,127The choice of the muscle relaxant is not critical, and Intubationnearly all currently available drugs with a short to There is still controversy over the question of whether the incidence of difﬁcult tracheal intubation is higher in obese patients,129–131 but although there does not Anaesthesia for bariatric surgery: basic considerations seem to be a direct correlation between body weight or • General anaesthesia with endotracheal intubation and BMI and grade of difﬁculty, it does appear that difﬁ- mechanical ventilation cult intubation is more common in patients with mod- – Calculate minute ventilation on basis of lean body erate to morbid obesity.129,131 In studies correlating weight classical risk predictors for difﬁcult intubation, such as – Avoid extreme tidal volumes the Mallampati score,115 thryomental distance, mobil- – Add slight PEEP to improve oxygenation ity of head and neck, interincisor gap and mandibular • Balanced anaesthetic with propofol or desﬂurane and recession with difﬁcult visualization of the larynx132 remifentanil – Propofol dosed according to total body weight and difﬁcult intubation, the single independent risk – Isoﬂurane or sevoﬂurane acceptable alternatives factor that could be found was a Mallampati score of 3 – Remifentanil dosed according to IBW or LBM or higher.129–131 The positive predictive value of 66.7% – Alfentanil or sufentanil possible alternatives to with a sensitivity of 88.9–100% was higher in obese remifentanil patients than in the general population.131 In one • Choice of muscle relaxant not critical (except for long- study, neck circumference was also found to be an acting agents) independent risk factor for difﬁcult laryngoscopy; a – Relaxants cumulate in same manner in obese and Cormack–Lehane class III or higher was found in 5% lean patients of patients with a neck circumference of 40 cm while – Effects can be reversed the incidence increased to 35% in patients with a
B A R I AT R I C S U R G E RY 113neck circumference of 60 cm.130 A barrel-chest orvoluminous breasts are occasional extrathoracicimpediments to intubation that can be circumventedby proper positioning of the patient or by the use of ashort-handled laryngoscope.A number of authors have advocated awake intubationin all morbidly obese patients. This is an unpleasantprocedure for the patient, and as studies have shown,only truly indicated in a minority of all cases. A prag-matic approach is to apply topical anaesthesia to phar-ynx, supralaryngeal area and tongue and to take an“awake look”. If the epiglottis and dorsal larynx can-not be visualized using gentle pressure of the laryn- (a)goscope, one should resort to awake, ﬁbre-opticnasotracheal intubation. This is performed in theusual manner using only the barest minimum ofsedative and analgesic drugs; preferably propofol andremifentanil or alfentanil.In order to facilitate intubation, the obese patientshould be positioned with pads or towels under theshoulders with the head elevated and the neckextended in order to bring the chin anterior to thechest (Figure 8.4). The patient should breathe 100%O2 through a tight-ﬁtting face mask for a minimum of3 min or until the end-expiratory O2 concentration is85% or above. Obese patients tolerate hypoventilation (b)and apnoea much worse and O2 saturation tends tofall more rapidly after cessation of respiration than in Figure 8.4 Obese patient position for intubation. Thisthe non-obese. This is likely to be a consequence of patient is 175 cm tall with a BMI of 51. With the patient intheir reduced FRC.55 During apnoea after a period of the normal supine Jackson position (a) the chin is lowerpre-oxygenation that brought the end-tidal O2 con- than the chest, and one will probably encounter difﬁcultiescentration to 95% or higher, arterial O2 saturation in inserting the laryngoscope. Slightly elevating the upperdropped below 90% more than twice as fast in mor- body and reclining the head (b) brings the chin higher thanbidly obese patients than in lean individuals (163 vs. the chest and facilitates mouth opening and insertion of the364 s).133 laryngoscope.A rapid-sequence induction using succinylcholine formuscle relaxation is recommended to minimize therisk of aspiration pneumonitis. This will also permitone to await the return of spontaneous respirationshould all attempts at intubation fail. Some authors Intubation of obese patientsrecommend inserting a laryngeal mask airway as atemporary ventilatory device when initial attempts at • Intubation frequently more difﬁcult than in lean patientsintubation have failed.134 In the reported series, – None of the commonly used indicators of difﬁcultplacement of the airway was successful in all cases, intubation are very speciﬁc or selectivebut tracheal intubation ultimately failed in 3% of the – Mallampati score most closely associated with dif-patients. In these patients, surgery was carried out ﬁcult intubationuneventfully using the laryngeal mask airway. A sec- • Neck should be extended and chin anterior to chest:ond option is to use an intubating laryngeal mask – Voluminous breasts or barrel-chest can interfereairway as a ventilatory device through which the with the introduction of the laryngoscopeendotracheal tube can be inserted with less risk of • Effective pre-oxygenation, rapid intubation: – O2 saturation falls rapidly in obese patientshypoxemic episodes.135 In any case, care must betaken to position the tip of the endotracheal tube cor- • Laryngeal mask airway as temporary device if intub- ation failsrectly in relation to the carina, and to detect and, if
114 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYnecessary, to amend any changes. The tip of the endo- Unconsciousness is maintained with propofol, desﬂu-tracheal tube was found to descend in 50% of mor- rane or isoﬂurane. Propofol is infused at a rate ofbidly obese patients undergoing laparoscopic gastric 5–6 mg kgϪ1 hϪ1 based on total body weight. Alterna-banding and to enter the right bronchus in one-third tively, a TCI system can be used with the propofolof these patients.136 plasma concentration set at 2.0–2.5 g mlϪ1. The volatile anaesthetic is given at an end-tidal concentra- tion of 0.5 MAC. Complete muscle relaxation is crucialIntraoperative considerations during all laparoscopic surgery, but this is particularly the case for bariatric procedures in order to maintainFaced with a patient presenting with such current and an adequate intra-abdominal working space with thepotential problems, one would intuitively tend to preset inﬂation pressure. Relaxometry is desirable, butopt for maximum monitoring and postoperative care. not always possible in the obese patient. A reduction ofThis may not always be necessary as a study comparing the space in the pneumoperitoneum should be taken asthe outcome after gastric reduction surgery demon- a clinical sign that the effects of the muscle relaxant arestrated.137 Thirty-six patients were treated in hospital waning. For further details refer to the chapter onA with high intensity intraoperative monitoring and anaesthesia.routine postoperative ventilation on an intensive careunit. The patients were equipped with an arterial line,two intravenous lines and a urinary catheter. The Monitoringanaesthetic was with 0.7 MAC isoﬂurane, 53% nitrousoxide, pancuronium (13.2 mg, reversed in only ﬁve Intraoperative monitoring for bariatric surgery shouldpatients) and sometimes fentanyl (only 26 of the include continuous ECG, preferably with continuouspatients, and only a moderate dose of 0.7 mg). On aver- ST evaluation, continuous or intermittent blood pres-age, the patients had a 46.5-h stay in the intensive care sure measurement, pulse oximetry, capnometry andunit and a 9.7-day postoperative stay in the hospital. relaxometry. Patients with severe cardiopulmonaryThe 50 patients in hospital B, on the other hand, were disease might beneﬁt from CO and pulmonary arteryequipped only with one intravenous line, no arterial pressure monitoring.line, no urinary catheter, and postoperative ventilationwas not planned. The anaesthetic was with nitrous Except for all but minor procedures and in otherwiseoxide (64%), fentanyl (1.3 mg) and pancuronium healthy obese patients, blood pressure should be moni-(9.7 mg). Isoﬂurane was only given to 14 patients, and tored invasively through an intra-arterial catheter.then in a low dose of 0.3 MAC. Respiratory depression Most of these patients have one or several cardiovascu-and muscle relaxation were routinely reversed with lar risk factors. Laparoscopic procedures compromisenaloxone and pyridostigmine allowing extubation in CO and blood pressure should be closely monitored.the operating theatre. The patients spent 1.7 h in the Non-invasive pressure measurements are difﬁcult torecovery room and 9.6 postoperative days in the hospi- obtain due to the poor ﬁt of blood pressure cuffs on thetal. The outcome was the same in both hospitals, but conical shape of the upper arms. If one decides to usethe costs differed signiﬁcantly. non-invasive blood pressure measurements, one must be certain that the bladder in the cuff is long enough toThe data are interesting and thought provoking, but we encircle at least 75% of the circumference of the arm.believe, nonetheless, that state-of-the-art anaesthetic Blood pressure measurements with a constant, pre-management of morbidly obese patients frequently dictable bias can be obtained from the wrist, and thisrequires invasive intraoperative monitoring and inten- method could be an acceptable alternative.138sive postoperative respiratory care. Cardiovascular andrespiratory co-morbidity is so frequent, and the func-tional reserves of these patients so slim that lack of Technical assistanceattention to perioperative care can have catastrophic The anaesthetist is frequently requested to place aconsequences. bougie, nasogastric tube or intragastric balloon dur- ing surgery that the surgeon will use to size the gas- tric pouch or to calibrate the diameter of the stoma.Maintenance of anaesthesia The anaesthetist might also be asked to help performAnaesthesia is maintained as a balanced technique with the leak test by injecting air, methylene blue, etc.remifentanil infused at a rate adequate to suppress into the gastric tube to assess anastomotic integrity.autonomic responses to noxious stimuli. This is usually This must be done carefully in order not to disrupt thebetween 0.2 and 0.5 g kgϪ1 minϪ1 based on LBM. staple line. Care must be taken to prevent introduction
B A R I AT R I C S U R G E RY 115of methylene blue into the patient’s lungs. All endo- Continuous epidural analgesia is sometimes con-gastric tubes must be removed completely before gas- sidered to be better than conventional pain therapytroplasty or gastric diversion is performed to avoid with intravenous opioids, involving less impairmentstapling or transecting these objects. Once the pouch of gastrointestinal function or sensorial obtundation.has been formed, great care must be exercised when However, a study comparing epidural analgesia withreintroducing the nasogastric tube. bupivacaine and fentanyl to patient-controlled anal- gesia (PCA) with intravenous morphine after gastricPostoperative considerations bypass surgery was unable to conﬁrm this.140 There was no difference between the groups with regard toExtubation pain control, time to ambulation, time to ﬁrst ﬂatus, occurrence of nausea or pruritus, and length of hos-The trachea should be extubated postoperatively pital stay. Wound infection was 85% in the epiduralonly when the patient is fully awake and in a semi- group, but only 38% in the PCA group (P Ͻ 0.01).recumbent position. Supplemental O2 should be admin- Epidural analgesia is not warranted in laparoscopicistered and pulse oximetric monitoring continued bariatric surgery, since there is only little pain and theuntil it is certain that there is no longer a risk of alve- procedures are designed to be minimally invasive andolar hypoxia and hypoxaemia that would increase pul- permit earliest possible ambulation.monary vascular resistance. A course of nasal CPAPmight be beneﬁcial, particularly during the third toﬁfth night when rapid eye movement (REM) sleep Thromboprophylaxisrebound and sleep apnoea phases reach a maximumeven when opioids are avoided.139 Morbid obesity is a major independent risk factor for death from postoperative pulmonary embolism on the basis of deep vein thrombosis.141 SubcutaneouslyPostoperative analgesia administered heparin (5000 IU every 12 h) reduces the incidence of thrombosis. Low molecular weightIt is important to provide not only adequate pain relief heparins are as effective as non-fractionated heparinat rest, but also to allow deep breathing and coughing. in reducing postoperative deep vein thrombosis butThis is of particular importance in the obese patient more cost effective and with fewer side effects.142 Bothdue to the higher likelihood of alveolar collapse and enoxaparin and nadroparin were effective in random-atelectasis. The pain potential of laparoscopic oper- ized studies.143,144 A recent survey of the preferredations is much lower than that of their conventional method used to prevent thromboembolism in a largeopen counterparts. Regimens for postoperative pain association for bariatric surgery showed that 50% usedtherapy will have to take this into account and rely subcutaneous unfractionated heparin, 5000 IU everymore on minor analgesics than on opiates. 8–12 h, 33% used pneumatic compression stockingsWe take a multimodal approach to postoperative pain and 13% used low molecular weight heparin.145therapy. Our ﬁrst line analgesic is a more or less spe- Although the main responsibility of thromboprophy-ciﬁc cyclo-oxygenase (Cox) 2 inhibitor. This can be laxis rests with the surgeon, the anaesthetist can con-diclofenac, naproxen, rofecoxib, valdecoxib or some- tribute to the efforts by giving an anaesthetic thatthing similar. Ibuprofen is more speciﬁc for Cox-1, as allows earliest possible mobilization of the patient.is acetylsalicylic acid, and will inhibit thrombocytefunction to a greater degree and cause more bleeding.Our initial analgesic is diclofenac 100 mg given as a Referencessuppository after induction of anaesthesia, or rofe- 1. Wittgrove AC, Clark GW, Schubert KR. Laparoscopiccoxib 50 mg or valdecoxib 40 mg given orally together gastric bypass, Roux-en-Y: technique and results in 75with the premedication. The latter alternative is easier patients with 3–30 months follow-up. Obes Surg 1996;to comply with, less likely to be forgotten and thus 6: 500–504.preferable. The effect of the ﬁrst agent is augmented 2. Belachew M, Jacqet P, Lardinois F, Karler C. Verticalpostoperatively with intravenous paracetamol (acet- banded gastroplasty vs adjustable silicone gastric band-aminophen). This combination is frequently sufﬁcient ing in the treatment of morbid obesity: a preliminary report. Obes Surg 1993; 3: 275–278.to reduce the postoperative pain to a tolerable level 3. Chua TY, Mendiola RM. Laparoscopic verticaland to make the patient comfortable. If not, the banded gastroplasty: the Milwaukee experience. Obesresidual pain is treated by intravenous bolus injec- Surg 1995; 5: 77–80.tions of morphine (2 mg) as requested by the patient. 4. Lonroth H, Dalenback J, Haglind E, Lundell L.Subcutaneous injections should be avoided, since Laparoscopic gastric bypass. Another option inabsorption is extremely unreliable. bariatric surgery. Surg Endosc 1996; 10: 636–638.
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MINIMALLY INVASIVE THORACIC SURGERY 9Minimally invasive endoscopic surgery of thoracic pneumonology in the treatment of airway tumoursorgans can be performed by bronchoscopy, medi- (see Chapter 10).astinoscopy or thoracoscopy and usually involves the The modern rigid bronchoscope is a metal tube,lungs, the pericardium, the oesophagus, the thymus, available in various sizes, with a bevelled, slightlythe thoracic part of the sympathetic nervous system and flared distal end, and a proximal end with a side-armoccasionally the thoracic spine. The following, non- for attaching the anaesthetic breathing system (Figureinclusive list gives an idea of the scope of present indi- 9.1). The open proximal end can be occluded with ancations for endoscopic thoracic surgery (Table 9.1). eyepiece or a port, which allows the introduction of the rod telescope and permits simultaneous bron-Bronchoscopy choscopy and ventilation. Since the bronchoscope does not have a snug ﬁt in the trachea there is always aBronchoscopy is possibly the oldest endoscopic pro- gas leak of variable magnitude. Some bronchoscopescedure used in the diagnosis and treatment of intratho- incorporate a channel to allow Venturi jet ventilation.racic disease processes. In 1897, Gustav Killian used a Rigid bronchoscopy causes signiﬁcant surgical stimu-Mikulicz-Rosenheim oesophagoscope to extract a bone lation and requires hyperextension of the neck, and islodged in the right main bronchus of a 63-year-old therefore routinely performed in general anaesthesia.man.1 Chevalier Jackson and Victor Negus were instru- The rigid bronchoscope in combination with a rodmental in the introduction of the technique in the US telescope gives a very detailed view and permitsand the UK. Innovations in ﬁbre-optics led to the extensive endobronchial instrumentation, such asdevelopment of a ﬂexible bronchoscope and its intro- removal of foreign bodies, placement of stents andduction into clinical practice by Shijeto Ikeda in 1968. resection of airway tumours. Lasers are frequently usedThe rise of the ﬁeld of interventional pneumonologyis directly related to improvements of bronchoscopicinstruments. There is considerable overlap of thedepartments of otorhinolaryngology and interventional Table 9.1 Techniques and indications in endoscopic thoracic surgery Bronchoscopy Rigid • Removal of foreign bodies, stent placement, resec- tion of airway tumours, diagnosis and treatment of haemoptysis, removal of granulations Flexible • Diagnostic, bronchial alveolar lavage, removal of secretions in intensive care patients Mediastinoscopy • Diagnostic biopsies (e.g. lung malignancies, lymphomas), treatment of retrosternal masses (e.g. Figure 9.1 Rigid bronchoscopes in various sizes for patients thymus, thyroid gland) ranging from the neonate to the adult. The instrument for Thoracoscopy the adult patient is equipped with a ﬁbre-optic cable to the light source and has an attachment for connecting it to the • Diagnostic, lung resection, (segment, lobe), peri- anaesthesia machine. The end piece with a slider containing cardectomy, thoracic sympathectomy, oesophagus resection, resection of masses in lower mediastinum, a closed glass observation port, an open aperture for insert- spinal surgery ing instruments and a self-sealing port for inserting the rod telescope is seen below the adult instrument.
122 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Figure 9.2 Flexible broncho- scopes for adult and paediatric patients. The thumb lever for manipulating the bronchoscope tip is seen at the lower edge of the headpiece adjacent to the eyepiece. The port for the instru- ment channel is visible on the upper distal edge of the head- piece. The larger instrument has a separate side-port for attach- ing and activating suction.for the latter indication (see Chapter 10). The rigid for bronchoscopy other than for removal of a foreignbronchoscope is the instrument of choice in small body frequently have a long history of cigarette smoking,children and in patients with massive endobronchial and consequently a hyper-reactive bronchial system,bleeding. Rigid bronchoscopy was displaced by ﬂex- impaired pulmonary function and probably concomi-ible bronchoscopy in the 1970s and early 1980s, but tant cardiovascular disease.the work of Jean-François Dumon in France brought The preoperative assessment of these patients shouldabout a renaissance of the technique in Europe. be aimed at determining the severity of their cardiopul-The ﬂexible bronchoscope consists of a long, tubular monary impairment, and whether it can be improved.structure, available in various diameters, with a tip The routine preoperative investigation includes athat can be moved up and down in one plane. Bundles standard laboratory work-up, 12-lead electrocardio-of glass ﬁbres are incorporated into this structure gram (ECG) and chest radiograph. The latter maywhich conduct light from a cold-light source for illu- reveal atelectatic or consolidated areas, pneumothorax,minating the ﬁeld under observation, and transmit pleural effusions, or a localized hyperinﬂated areathe picture to the eyepiece. Larger instruments have a indicative of a foreign body obstructing a bronchus insuction channel, which can also be used to introduce a ball-valve fashion (Figure 9.5(b)). Pulmonary func-instruments, apply drugs or remove secretions. The tion testing and a preoperative blood gas analysis areview obtained with the ﬂexible bronchoscope is not frequently indicated.as deﬁned as that of the telescopes used in rigid Rigid bronchoscopy requires hyperextension of thebronchoscopy, and the thinner the bronchoscope the neck and the preoperative examination should includepoorer the view. One is also limited in the manipula- an assessment of the mobility of the cervical spine.tions that are possible through the instrument chan- Patients with cervical ankylosis, or micro- or retrog-nel. On the other hand, ﬂexible bronchoscopy can be nathism may not be suited for rigid bronchoscopy.performed on the awake patient under topical anaes- Cervical involvement of chronic polyarthritis predis-thesia. Flexible bronchoscopy is typically performed poses to luxation of the ﬁrst and second cervical verte-as an initial measure to inspect the airways and to brae with the risk of damage to the cervical spinal cord.obtain specimens for further assessment when airwaypathology is suspected. It has a number of indications Premedication for bronchoscopy might include a short-in the intensive care unit, such as removal of retained acting benzodiazepine such as midazolam to relievesecretions from the bronchi of intubated and venti- anxiety, but heavy sedation should be avoided in patientslated patients, conﬁrmation of correct endotrachealtube position, and protected collection of specimens Characteristics of patients presenting forfor the diagnosis of ventilator-associated infections.2–6 bronchoscopy • Foreign body removalPreparing the patient for bronchoscopy – Usually children, usually healthy, atelectasis possibleChildren are commonly referred for bronchoscopy for • Pulmonary or bronchial pathologyremoval of foreign bodies from the airway, diagnosis – Chronic obstructive lung disease (COLD), ischaemic heart disease, arterial hypertension, atelectasis,of airway stenosis (e.g. tracheomalacia) or for surgical pleural effusions, pneumothorax, bronchus occlu-treatment of tracheal papillomatosis. These patients sion, hyper-reactive airwaysare usually otherwise healthy. Adult patients presenting
M I N I M A L L Y I N VA S I V E T H O R A C I C S U R G E RY 123with suspected airway obstruction. An anticholinergic Anaesthesia for bronchoscopydrug, such as glycopyrrolate or atropine, is frequentlygiven in the endeavour to reduce bronchial secretions Flexible bronchoscopyand aid visualization.7 But studies have shown that Flexible bronchoscopy is commonly performed as anthey are possibly ineffective in this respect,8 and might outpatient procedure on the awake, spontaneouslyincrease the incidence of hypertension and cardiac breathing patient. General anaesthesia is reserved fordysrhythmias.9 Patients should be given their regular patients unable to co-operate or otherwise unable toantihypertensive, antidysrhythmic and bronchodila- tolerate the procedure. The bronchoscope can betory medication. introduced through the mouth or the nose. If the lat- ter is chosen, the nasal mucosa is anaesthetized with aCardiopulmonary complications are common during topically applied local anaesthetic combined with aboth ﬂexible and rigid bronchoscopy10–13 and moni- vasoconstrictor as a decongestant. The pharynx andtoring should take this into account. Monitoring should hypopharynx can be anaesthetized by direct applica-include continuous ECG and pulse oximetry, non- tion of a local anaesthetic spray. The local anaestheticinvasive blood pressure measurement and capnometry can be applied to the larynx and lower airways by trans-during general anaesthesia. Measuring end-tidal carbon cricothyroid injection, nebulization or applicationdioxide (CO2) concentrations is difﬁcult during rigid under direct vision through the instrument channelbronchoscopy due to the air leak around the instru- of the bronchoscope.14 Considerable amounts of localment. Transcutaneous measurement of arterial anaesthetic are required for adequate anaesthesia, andcarbon dioxide tension, as mentioned in Chapter 4, plasma concentrations can reach toxic, and occasionallywould be a suitable alternative during lengthy pro- lethal levels.15,16 One must be aware of this and observecedures. Airway pressure (PAW) and expiratory gas the patient for signs of local anaesthetic toxicity.ﬂow should be monitored closely, since the bronchialirritation associated with the procedure can provoke If required, sedation can be provided by the intravenousbronchospasm. application of midazolam or propofol. Propofol is moreFigure 9.3 Flexible bronchoscopy through the endotracheal tube. The right picture shows the bronchoscope in the self-sealingadapter that allows simultaneous bronchoscopy and ventilation. The carina is visible on the video screen in the background.
124 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYexpensive than midazolam but allows better control reliably, and should be used for all longer proce-over the depth of sedation.17,18 An opioid may be added dures. Muscle relaxation can be provided during veryto provide better analgesia and suppress the cough short procedures with the repetitive administrationreﬂex to a certain degree, but one must keep the syn- of succinylcholine, but a longer acting agent, such asergistic depressive effects on respiration in mind. mivacurium, atracurium, vecuronium or rocuronium, should be used if a duration of more than 10–15 minDuring general anaesthesia, the bronchoscope can be is anticipated in order to avoid prolonged competitiveinserted through a self-sealing port in the angle piece block from succinylcholine metabolites.20connected to the endotracheal tube allowing ventila-tion to continue (Figure 9.3). The largest possibleendotracheal tube must be used, since the broncho- Anaesthesia for rigid bronchoscopy of shortscope signiﬁcantly reduces the open cross section. durationResistance to gas ﬂow is increased in the endotracheal • Oral (or intravenous) premedication with short-tube and the ventilatory pattern must be adapted acting benzodiazepineaccordingly with prolongation of the expiratory phase. • Alfentanil (20 g kgϪ1) or other suitable opioid. WaitNeuromuscular relaxation is not mandatory, but if for effect to set in (90 s)desired, a short-acting agent should be used. Flexible • Induction with propofol, methohexital or etomidatebronchoscopy can also be performed through a laryn- (thiopental gives slower recovery)geal mask airway. The stem of the mask airway nor- • Relaxation with succinylcholine (1.5 mg kgϪ1) aftermally has a larger diameter than the endotracheal tube, low-dose precurarization, if desiredand the increase in gas ﬂow resistance caused by the • Maintenance with repeated doses of hypnotic and succinylcholine as requiredbronchoscope will be less. Spontaneous respirationmight be a feasible alternative in this case. Anotheralternative is to insert the bronchoscope through the Rigid bronchoscopy can be performed under inhala-aperture of a suitably modiﬁed face mask, such as the tional anaesthesia on the spontaneously breathingPatil mask (Figure 9.4).19 There is no obstruction of patient, and this is still the method of choice in someairway tubing and little impairment of spontaneous centres. A deep plane of anaesthesia is required torespiration. abolish airway reﬂexes, and the line between excessive depth with hypoventilation on the one hand, and bronchospasm or laryngospasm due to inadequateRigid bronchoscopy anaesthesia, on the other, is narrow. Sevoﬂurane isRigid bronchoscopy is performed under general superior to halothane with regard to incidence ofanaesthesia, usually with controlled ventilation. The complications and to recovery time.21patient is positioned with the upper body slightlyelevated and the neck strongly retroﬂexed to give There are number of ways to manage ventilation duringstraight access to the larynx (Figure 9.5). Any general rigid bronchoscopy, among which are apnoeic oxy-anaesthetic regimen is possible, but intravenous tech- genation, use of the ventilating bronchoscope, andniques are preferred, since the gas leak around the various methods of jet ventilation. The apnoeic tech-bronchoscope leads to a high level of workspace air nique and jet ventilation are described in detail inpollution when volatile anaesthetics are used. A total Chapter 10. The ventilating bronchoscope can beintravenous technique with propofol and an opioid, compared to an unblocked endotracheal tube with ansuch as remifentanil or alfentanil as described in undeﬁned and changing volume of gas leakage aroundChapter 5, gives optimal control of the depth of the distal end. Large leaks can be reduced by packinganaesthesia. The plane of anaesthesia must be sufﬁ- the posterior pharynx, mouth and nose with gauze.ciently deep to prevent airway responses such as bron- The proximal end of the bronchoscope has a cap withchospasm, laryngospasm, or bucking and coughing. a slide that can occlude the opening with an eyepieceNeuromuscular relaxation is not mandatory, but with or allow introduction of the telescope through a self-its judicious use the amount of anaesthetic can be sealing port (see Figure 9.1). The slide also has anreduced considerably. For short procedures lasting not opening through which instruments can be introducedlonger than 10–15 min, intermittent bolus doses of for suctioning or removing material. The efﬁcacy ofpropofol, methohexital or etomidate can be given. ventilation with the ventilating bronchoscope is difﬁcultThere is a certain risk of intraoperative awareness with to assess, since end-tidal gas contains an unknownthis method when signs of awakening are used to guide amount of dead-space air and capnometry consistentlythe administration of the anaesthetic. Propofol admin- yields values that are too low. There is thus a highistered by continuous infusion prevents awareness more risk of hypoventilation and hypercapnia, which is
M I N I M A L L Y I N VA S I V E T H O R A C I C S U R G E RY 125 Figure 9.4 Flexible bron- choscopy through the self-sealing membrane in a face mask. The anaesthetist controls the airway and ventilation while the endo- scopist performs the bron- choscopy. Both can follow the procedure on the video screen. The bronchoscope can be inserted either orally or through the nasal passage. A bite guard is used if the instrument is inserted through the mouth. (Photograph courtesy of Dr Arnd Timmermann, Department of Anaesthesiology, Emergency and Intensive Care Medicine, Univer- sity of Göttingen.)compounded by the interruption of ventilation that patency. Patients with persisting haemorrhage oroccurs whenever the slide is opened. purulent infection in one lung should be positioned on their sides with the affected lung down in order toThe pharynx should be inspected at the end of the prevent contamination of the healthy lung.procedures performed under general anaesthesia toremove secretions and blood. Neuromuscular block is Complications of bronchoscopyreversed if necessary, the bronchoscope is removedand the airway is managed with a face mask and The rigid bronchoscope can cause structural damage tooropharyngeal tube. A laryngeal mask airway or endo- the tracheobronchial system resulting in haemorrhage,tracheal tube may also be inserted to maintain airway oedema or mucosal perforation with subsequent
126 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY(a)(b) (c)Figure 9.5 Rigid bronchoscopy. (a) Patient undergoing rigid bronchoscopy to remove foreign object. The bronchoscope isin place and the surgeon is inspecting the right bronchus with a rod telescope inserted through the bronchoscope. The ﬂex-ible connection of the anaesthesia machine with the rigid bronchoscope is readily visible. (b) Foreign object visible in projec-tion on the right main bronchus. The right upper lobe appears hyperinﬂated, which would be the case if the foreign objectobstructed the right upper lobe bronchus. (c) Dental bridge removed from the right main bronchus of the patient. (ChestX-ray and photograph of bridge courtesy of Dr Ralph Rödel, Department of Otorhinolaryngology, University of Göttingen.)
M I N I M A L L Y I N VA S I V E T H O R A C I C S U R G E RY 127 Table 9.2 Complications of bronchoscopy Mechanical effects • Damage to teeth, larynx or vocal cords on insertion, bronchial or tracheal perforation, pneumothorax, subcutaneous emphysema, barotrauma, haemor- rhage, airway obstruction Physiological reactions • Subglottic oedema, bronchospasm, laryngospasm, hypoxaemia, arterial hypertension, cardiac dysrhyth- mias, tachycardia Foreign substances • Local anaesthetic toxicity, loss of swabs or other materialsubcutaneous emphysema or pneumothorax. Incor-rectly applied jet ventilation can cause pulmonary Figure 9.6 Mediastinoscopes of different sizes. The coiledbarotrauma and pneumothorax (see Chapter 10). ﬂexible lightguide is connected to the ﬁbre-optic light con- ductor integrated into the inner wall of the instrument.Signiﬁcant cardiovascular reactions with considerableincreases of heart rate and arterial pressure and signs parasternal incision in the second intercostal inter-of myocardial ischaemia can occur during rigid bron- space, usually on the left side. This approach giveschoscopy.22,23 The magnitude and severity of the access to the lower mediastinum on the side of theresponse is reduced when propofol is employed instead incision. During cervical mediastinoscopy the instru-of thiopental. One might consider the intravenous ment is in direct contact with the great vessels of theadministration of a beta-adrenergic antagonist, such upper thorax, with the oesophagus, the trachea andas esmolol, atenolol or metoprolol, to improve cardio- the recurrent laryngeal nerve (Figure 9.7).vascular stability. Cardiac dysrhythmias are commonduring rigid and ﬂexible bronchoscopy. The intense Mediastinoscopy is primarily a procedure used tovagal stimulation can induce bradycardia which occa- obtain tissue for the histological diagnosis of a medi-sionally requires treatment with atropine or glycopy- astinal mass. This is crucial for planning therapy, sincerrolate. Other dysrhythmias are caused by sympathetic lymphomas, metastatic lung malignancies, sarcoido-stimulation, and can be aggravated by hypoventilation sis, thymomas or tuberculosis – to list the most com-with hypoxia and hypercapnia.24,25 This should be monly detected diseases – will each require a differentcorrected before pharmacological therapy is instituted. therapeutic management. Improved resolution of mag- netic resonance imaging and computed tomographyAirway obstruction due to laryngeal oedema or laryn- has reduced the need for mediastinoscopy in many cases.gospasm can occur after completion of rigid bron-choscopy. Relaxation and reintubation of the trachea Mediastinoscopy is a relatively safe procedure with anmay be required in severe cases. incidence of major complications of approximately 0.5%27 and an operative mortality of 0.1% in a series of more than 6000 patients.28 There is little postoper- ative discomfort,29 and the procedure is commonlyMediastinoscopy performed on an outpatient basis. The unscheduled postoperative hospital admission rate is between 1%Carlens introduced cervical mediastinoscopy in 1959 and 4%.30–32 Mediastinoscopy is contraindicated as aas a method to obtain biopsy material from the super- repeat procedure since the plane of dissection is oblit-ior mediastinum posterior to the great vessels without erated by scarring. Superior vena cava syndrome, severehaving to perform a thoracotomy.26 In this procedure, tracheal deviation and thoracic aortic aneurysm area small transverse incision is made cephalad to the relative contraindications to the procedure.jugulum through which the mediastinoscope (Figure9.6) is inserted behind the manubrium into the medi- Preparing the patient for mediastinoscopyastinum. In the less common approach known as theChamberlain procedure, or anterior mediastinoscopy, Patients scheduled for mediastinoscopy can presentthe instrument is inserted through a transverse with a wide variety of clinical symptoms. They can
128 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYRight common Tracheacarotid artery MediastinoscopeRightsubclavianartery Left subclavian arteryInnominatearteryAorta Figure 9.8 Patient position for mediastinoscopy. (Illustra-Figure 9.7 Topographical anatomy of upper mediastinum tions by courtesy of Dr Hilmar Dörge, Department ofduring mediastinoscopy. The mediastinoscope is in direct Cardiothoracic Surgery, University of Göttingen.) (a) Thecontact with the innominate artery, aorta and trachea. The upper body is elevated and the neck is extended to giveinnominate artery can be completely occluded by pressure direct access to the manubrium and jugulum. (b) The sur-with the instrument, which will cause loss of radial artery geon makes a small transverse incision and inserts the medi-pulse in the right arm and right-sided cerebral ischaemia. astinoscope after blunt digital dissection of the correct plane.(Adapted from Ref .)range from the totally asymptomatic patient with a possibility of these co-existing diseases and activelymediastinal mass discovered on a routine chest X-ray, search for signs or symptoms. Figure 9.8a illustratesto the dyspoeic, cyanotic patient with superior vena the positioning of patient for mediastinoscopy.cava obstruction. Numerous diseases requiring amediastinoscopy for ultimate diagnostic clariﬁcationare associated with clinically relevant, and typical, Co-existing diseases in patients presenting forco-morbidities. Patients with small-cell lung cancer mediastinoscopycan suffer from a paraneoplastic syndrome with • Lung cancer: paraneoplastic syndromes, dyspnoea,symptoms including hypercalcaemia, hyponatraemia, atelectasis, tracheal inﬁltrationhypercortisolaemia, acromegaly, encephalitis, para- or • Thymoma: myasthenia gravisquadriplegia secondary to necrotizing myelitis and • Sarcoidosis: myocardial dysfunction, cardiac dys-Lambert–Eaton myasthenic syndrome. Thymoma is rhythmias, congestive heart failure, pulmonarya common cause of an anterior mediastinal mass, ﬁbrosisand is frequently associated with myasthenia gravis.Approximately 5% of patients with sarcoidosis havesigniﬁcant cardiac dysfunction, with dysrhythmias, Mediastinoscopy carries a deﬁnite risk of haemor-conduction disturbances, pericarditis, and congestive rhage, and at least two units of blood should be typedheart failure. The anaesthetist must be aware of the and cross-matched before the operation.
M I N I M A L L Y I N VA S I V E T H O R A C I C S U R G E RY 129Anaesthetic management be left in place at least overnight. If this does not stop the bleeding and vital signs begin to deteriorate, aAn oral benzodiazepine can be given as premedica- thoracotomy is necessary. The posterolateral approachtion, but caution is advised in the patient with respira- is most commonly used, but a median sternotomy istory impairment or with myasthenia gravis. Two sometimes required.35 The role of the anaesthetist islarge-bore venous cannulae are inserted, one in the to replace blood losses, preferably with blood, ensureupper and one in the lower extremity. Blood pressure adequate perfusion pressure pharmacologically, treatmonitoring should be on the right arm, in order to cardiac dysrhythmias, and, if required, induce delib-detect compression of the innominate artery (see erate hypotension to reduce blood loss. It is not advis-below). Some authors recommend measuring blood able to lose precious time in replacing the initiallypressure on the left arm and monitoring blood ﬂow in inserted endotracheal tube with a double-lumen tube.the right arm by radial artery cannulation, continuous Transpleural surgical access can be facilitated by tem-palpation of the radial pulse, or pulse oximetry on a porarily disconnecting the anaesthesia machine, andﬁnger of the right hand. This will make it easier to compressing and retracting the lung before resumingdifferentiate between a spurious decrease in blood ventilation. Fluids and blood should be infused throughpressure due to vascular compression and hypoten- the venous cannula in the lower extremity, since itsion resulting from blood loss, while still allowing might simply drain from the injured vessel into theearly detection of innominate artery compression. mediastinum before reaching the right atrium if infusedMediastinoscopy has been performed under local into an arm vein.anaesthesia33 (not recommended) but general anaes- Pneumothorax is the second most common majorthesia with endotracheal intubation and controlled complication of mediastinoscopy. It is usually notventilation is preferable; surgery can proceed with detected until the postoperative period, and rarelyfewer interruptions, and the risk of pulmonary air requires decompression,28 but all patients shouldembolism is reduced. In patients without respiratory have a postoperative chest X-ray. Tension pneum-obstruction, anaesthesia is induced with propofol, othorax, occasionally even bilateral, can occur intraop-etomidate or a short-acting barbiturate after adequate eratively, causing an increase in PAW, hypotension,pre-oxygenation and administration of an opioid. arterial desaturation and reduced breath sounds onTracheal intubation is facilitated by the administra- the affected side. This complication requires immedi-tion of a neuromuscular blocking agent. The effect ate treatment with a chest tube.36and duration of action of these agents is enhanced inpatients with myasthenia. The dose must be reduced Compression of the innominate artery can criticallyin these patients and neuromuscular transmission reduce blood ﬂow in the right carotid artery leading tomust be monitored. Fibre-optic awake intubation or cerebral ischaemia with cerebral oedema and transientinhalation induction and tracheal intubation in deep or even permanent hemiparesis. Since compression ofanaesthesia should be considered in patients with sig- the innominate artery also causes loss of the right radialniﬁcant airway obstruction. pulse, this complication can be detected by continuous blood pressure measurement in the right arm.37A balanced anaesthetic technique with a combinationof an opioid and propofol or a volatile anaesthetic, In a series of over 2000 patients undergoing medi-such as isoﬂurane, desﬂurane or sevoﬂurane, is used astinoscopy, Puhakka found three cases of trachealfor maintenance. Nitrous oxide should be avoided due rupture and two cases of pericardial damage.27 PAWto the potential risk of pulmonary air embolism (see must be monitored closely, since compression of theChapter 6). trachea can impair ventilation. Pressure on the aorta can induce reﬂex bradycardia. Recurrent laryngeal nerve paralysis, if it occurs, is permanent in aboutComplications 50% of the cases.28 Pulmonary air embolism can occur if intrathoracic veins are opened, and the inci-Although the incidence of complications of medi- dence of this complication is likely to be higher in theastinoscopy is fairly low, those that do occur can be spontaneously breathing patient.sudden, severe and life threatening.28,34 Massive haem-orrhage from an injured or transected large, intratho-racic vessel is the most serious acute complication. ThoracoscopyAccess to the vessels through the mediastinoscope isdifﬁcult at best, and transected ends tend to retract As at the inception of laparoscopy, a cystoscope wasout of reach. The initial treatment is therefore to pack used to perform the ﬁrst recorded thoracoscopy.the mediastinum with a gauze tamponade, which can In 1910, Hans Christian Jacobeus, a Swedish internist
130 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Table 9.3 Complications of mediastinoscopy28,34 Table 9.4 Selected operations in thoracoscopic surgery • Haemorrhage, occasionally exsanguinating Lungs and pleura • Pneumothorax • Wedge resection, segmental resection, atypical • Recurrent laryngeal nerve paralysis resections • Infection • Excision of bullae • Phrenic nerve injury • Lobectomy • Left hemiparesis following compression of the • Pneumonectomy innominate artery • Removal of pulmonary metastases • Reﬂex bradycardia due to pressure on aorta • Diagnosis and treatment of pleural diseases • Oesophageal injury Heart • Chylothorax • Pericardectomy, pericardiocentesis • Pulmonary air embolism • Coronary artery surgery • Tracheal rupture, tracheal compression • Implantation of AICD devices • Pericardial injuries Oesophagus • Oesophagectomyworking in a tuberculosis sanatorium, performed a • Suture of oesophageal perforationsthoracoscopic lysis of pleural adhesions as prepar- Mediastinumation for lung collapse therapy.38 In the following years,he gathered considerable experience in the use of tho- • Removal of mediastinal massesracoscopy in the diagnosis of intrathoracic tumours.39 Thoracic spineThoracoscopy was commonly used early on to avoid • Disc herniationthe risks of general anaesthesia and thoracotomy in • Instrumentation and correction of spinal deformitiespatients with severe co-morbidity. The procedures were Miscellaneousvery short and were performed on the spontaneously • Thoracic sympathectomy for hyperhidrosisbreathing patient under local anaesthesia, perhaps with • Vagotomythe instillation of local anaesthetic into the pleural AICD: automatic implantable cardioverter deﬁbrillator.cavity. The reader is referred to Braimbridge40 for anintimate account of the early history of the technique.Although not the sole indication, treatment of pul-monary tuberculosis was the primary indication for Physiology of the lateral decubitus positionthoracoscopy, and the technique was largely aban- and open chestdoned following the advent of tuberculostatic drugs.It was resurrected in Europe in the following decades Thoracoscopic operations are performed with theas an elegant, minimally invasive procedure for the patient in the lateral decubitus position, and the lungdiagnosis of pleural tumours and treatment of pleural on the affected side is allowed to collapse to optimizeeffusions and later adopted in the US.41–43 surgical access. This combination has considerable adverse effects on respiratory physiology, and dealingThe development of video-assisted thoracoscopic with it in a competent manner is one of the primarysurgery (VATS) and the introduction of laser surgery anaesthesiological concerns during thoracoscopicled to an explosive diversiﬁcation of the indications for surgery.thoracoscopic surgery in the past 10–15 years, whichnow include procedures lasting several hours and The lateral decubitus position itself has little effectmaking great demands on the physiological reserves on the ventilation–perfusion ratio or on oxygenationof the patient and the skill of the anaesthetist. The in the spontaneously breathing patient with a closedﬁrst reports of a video-assisted thoracoscopic lobec- chest. The effects of gravity dictate that blood ﬂow istomy by Kirby in 199344 were followed shortly after greater in the dependent lung, while ventilation of theby the report of a thoracoscopic pneumonectomy by dependent lung is also greater as a result of the cepha-Walker.45 VATS has been used for operations ranging lad shift of the dependent hemidiaphragm, whichfrom the treatment of recurrent pneumothorax and shifts the respiratory mechanics of the dependentbullous lung disease, to oesophageal resection and aorto- hemithorax onto the steep slope of the pulmonarycoronary bypass surgery, thoracic sympathectomy, pressure–volume curve (Figure 9.9(a)). Both bloodinvasive assessment and therapy of thoracic injuries ﬂow and perfusion are reduced in the non-dependentin trauma patients to operations on the thoracic lung, and the ventilation–perfusion ratio is approxi-spine46–51 (Table 9.4). mately unity in both lungs. Negative pressure in the
M I N I M A L L Y I N VA S I V E T H O R A C I C S U R G E RY 131 Spontaneous Mechanical breathing ventilation V V —Ϸ1 — Ͼ1 Q Q Ventilation V V — Ͻ1 —Ϸ1 Q Q (a) Closed chest Perfusion Spontaneous Mechanical breathing ventilation V V — Ͼ1 —Ϸ0 Ventilation Q Q V V — Ͻ1 —Ͻ1 Q Q (b) Open chest PerfusionFigure 9.9 Schematic illustration of the changes in the ventilation–perfusion and pressure–volume relationships in a patientwith closed or open thorax and spontaneous breathing or mechanical ventilation in the lateral decubitus position. (Modiﬁedfrom Ref .)non-dependent pleura prevents a downward shift of active inspiration increases the negative pressure inthe mediastinum. the dependent hemithorax causing a further downward shift of the mediastinum. Tidal volume is reducedInduction of anaesthesia and institution of mechan- by the amount of the mediastinal shift. This can notical ventilation in the patient in the lateral decubitus only impair ventilation, but also venous return to theposition does not alter the distribution of the pul- right heart. Loss of negative intrathoracic pressuremonary blood ﬂow in the dependent and non- allows the non-dependent lung to collapse under thedependent lungs. The distribution of ventilation, on inﬂuence of its unopposed elastic recoil. During spon-the other hand, changes radically. The reduction in taneous breathing with an open chest, gas is essen-functional residual capacity (FRC) that occurs after tially sucked from the non-dependent lung duringinduction of anaesthesia causes each lung to move to a inspiration causing it to collapse still further. Duringdifferent position on the pressure–volume curve. The expiration, air exiting the dependent lung enters thedependent lung moves down from the efﬁcient, steep non-dependent lung inducing a slight re-inﬂation ofpart of the curve onto the ﬂat, non-compliant part, the latter. This reversal of normal lung movement iswhile the non-dependent lung shifts to a more com- referred to as “paradoxical respiration” (Figure 9.10).pliant volume (Figure 9.9(a)). This increases the venous The ventilation–perfusion ratio falls below unity inadmixture in the dependent lung and the dead-space both lungs with a subsequent increase in shunt perfu-ventilation (VD/VT) in the non-dependent lung. sion and venous admixture (Figure 9.9(b)).Opening the non-dependent hemithorax removes Positive pressure ventilation of the patient with anthe negative intrathoracic pressure and causes the open chest in the lateral decubitus position can allevi-mediastinum to shift downward in the spontaneously ate some of the problems arising in the spontaneouslybreathing patient under the inﬂuence of gravity and breathing patient. Mediastinal shift and paradoxicalthe negative intrapleural pressure in the dependent respiration are reduced, but the patient may still havehemithorax. Descent of the hemidiaphragm during a considerable ventilation–perfusion mismatch with
132 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Table 9.5 Cardiovascular effects of artiﬁcial pneumothorax with CO255 Inﬂation pressure Effects (%) 5 mmHg CI Ϫ36 SV Ϫ34 LVSWI Ϫ49 15 mmHg MAP Ϫ64 CI Ϫ81 LVSWI Ϫ95 CI: cardiac index; SV: stoke volume; MAP: mean arterial(a) pressure; LVSWI: left ventricular stroke work index. One-lung ventilation Although thoracoscopy was originally only considered a relative indication for OLV, the ventilatory technique has now become a virtual standard for all intratho- racic procedures, including thoracoscopic surgery. It is not absolutely indicated – thoracoscopy can be per- formed with two-lung ventilation in a pinch – but it has a very high priority. Lung separation OLV requires separation of the right and left lungs,(b) and the standard method for achieving this is theFigure 9.10 Schematic illustration of paradoxical lung double-lumen endotracheal tube. Bronchial blockersmovement in a patient with an open chest breathing spon- can be used in certain situations, and endobronchialtaneously in the lateral decubitus position. (Adapted from intubation with a suitably long, single-lumen tubeRef .) (a) During inspiration, the non-dependent, col- can be used to selectively ventilate one lung if otherlapsed lung in the open hemithorax collapses further as air methods are not available.moves from it into the dependent lung. (b) During expira-tion, the collapsed lung expands as exhaled air enters it A double-lumen endotracheal tube is essentially twofrom the dependent lung. tubes connected side by side, each with its own inﬂat- able cuff and its own connector for the anaesthesia machine (Figure 9.11). One tube is intended to enter a bronchus, while the other is considerably shorter andclinically relevant venous admixture and hypoxia. ends in the trachea. Double-lumen endotracheal tubesPerfusion remains higher in the dependent lung, but are available as right- or left-sided models, dependingventilation is now greater in the non-dependent lung. on which main bronchus the tip is intended to enter.The ventilation–perfusion ratio changes to shunt per- Both models permit separate inﬂation of each lung,fusion in the dependent and VD/VT in the non- but the left-sided tube is usually preferred. The pecu-dependent lung (Figure 9.9(b)). The impairment of liar anatomy of the bronchial tree makes it difﬁcult tosurgical access and progress of the operation caused avoid occluding the right upper lobe bronchus whenby the inﬂated non-dependent lung can be avoided by a right-sided tube is used. The right-sided tube hasallowing this lung to collapse and ventilating only the a separate opening at the tip (“Murphy eye”) and adependent lung, a technique known as one-lung ven- modiﬁcation of the cuff designed to prevent obstruc-tilation (OLV). Attempts have occasionally been made tion of the right upper lobe bronchus.to improve visibility even more by insufﬂating thepleural cavity with CO2, but this has been shown to The correct position is initially determined by ausculta-cause signiﬁcant haemodynamic compromise in ani- tion of the chest while selectively ventilating each lung.mal studies54 as well as in patients55 (Table 9.5). This alone is not sufﬁcient, and the proper position
M I N I M A L L Y I N VA S I V E T H O R A C I C S U R G E RY 133 Figure 9.11 Double-lumen endotracheal tubes. The devia- tion of the tips of the endo- bronchial portion is readily visible. The right-sided tube is at the top and the left-sided tube below. The inset shows the “Murphy eye”, an opening at the tip of the endobronchial catheter with a modiﬁcation of the cuff of the right-sided double-lumen endotracheal tube. This is to prevent occlu- sion of the right upper lobe bronchus when the tip is in position. Figure 9.12 Endotracheal tube with integrated endobronchial blocker. This is positioned in the bronchus to be blocked under direct vision through a ﬂexible bronchoscope and the cuff inﬂated to occlude the bronchus. The blocking catheter has an internal lumen through which the lung can be deﬂated, secre- tions can be removed and CPAP applied.must be conﬁrmed by ﬁbre-optic bronchoscopy, since Lung separation can be achieved in small patients, forstudies have shown the tube to be malpositioned in up whom the smallest double-lumen tube is too large,to almost half of the cases even though clinical signs had with a bronchial blocker, an implement that is notbeen positive.56 If not conﬁrmed by bronchoscopy and essentially different from a Fogarty catheter. In fact,corrected if necessary, troubles with intraoperative sep- Fogarty catheters are still frequently used for thisaration of the lungs and selective ventilation can arise in purpose. The bronchial blocker is introduced intoup to 25% of the patients.57 The correct position is ver- the trachea alongside the endotracheal tube and isiﬁed after intubation in the supine patient and then advanced into the desired position under direct visionreafﬁrmed after the patient has been brought into the through a ﬁbre-optic bronchoscope. Endotracheallateral decubitus position. The bronchoscope must tubes have been developed with a separate channel inremain available during surgery, since dislocation of the their wall through which the bronchial blocker can beendobronchial tip is not infrequent, particularly during passed58 (Figure 9.12). Bronchial blockade with a sim-surgical manipulation of intrathoracic organs. ple catheter has a number of disadvantages compared
134 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RYwith the double-lumen endotracheal tube for lung even though all volatile anaesthetics have a detrimen-separation, among which are incomplete collapse of tal effects on arterial oxygenation during one-lungthe non-dependent lung, and no way to effectively anaesthesia. Volatile anaesthetics do have the theore-suction or independently ventilate the non-depend- tical advantage over intravenous agents of inducingent lung. Modern blocking catheters have an internal bronchodilatation, a desired effect in patients withlumen that allows suctioning and application of con- COLD. However, airway narrowing and closure in thetinuous positive airway pressure (CPAP) to the non- typical COLD patient presenting for thoracoscopicventilated lung. In a recent study no difference was surgery is more likely to be due to inﬂammation andseen in effectiveness of lung collapse, or oxygen (O2) loss of elasticity than to increased bronchomotorsaturation and fraction of inspired O2 between a dou- tone, and the theoretical beneﬁt of the volatiles wouldble-lumen endotracheal tube and a bronchial blocker be unlikely to outweigh the impaired oxygenation.for minimally invasive coronary artery surgery.59 Practical management of OLVPhysiology of OLV OLV induces an obligatory right-to-left shunt ofAfter collapse of the non-dependent lung, there is an varying magnitude through the non-ventilated lungobligatory transpulmonary right-to-left shunt of blood with a consequent fall in arterial O2 saturation (SaO2).past non-ventilated alveoli that increases venous admix- The primary goal of optimal management of OLV isture and lowers arterial O2 tension. The alveolar– to maintain SaO2 at a safe level above 90%. Further,arterial O2 tension difference (PAO2 Ϫ PaO2) is larger secondary, goals are to ensure adequate elimination ofduring OLV than when both lungs are ventilated. But CO2 and, ﬁnally, to provide good operating condi-there are a number of factors that prevent arterial tions for the surgeon, in that order. If SaO2 is too low,oxygen tension from decreasing to dangerous levels as the ﬁrst measure is to conﬁrm the correct position ofprecipitously as one would expect based on calcula- the endobronchial tip, and to increase the inspiratorytions of blood ﬂow and ventilation.60 The most impor- O2 fraction, even to 1.0, if necessary. Faced with sig-tant of these is the increase in vascular resistance in niﬁcant shunt perfusion, the latter measure will oftenthe non-ventilated lung known as hypoxic pulmonary not be sufﬁcient to solve the problem, since blood ﬂow-vasoconstriction (HPV), which was ﬁrst described by ing through the ventilated lung will not be able tovon Euler and Liljestrand.61 This autoregulatory mech- take up enough O2 to compensate for the venousanism acts to divert blood ﬂow away from non-ventilated admixture in the non-ventilated lung. However, theareas to the ventilated lung, thereby preserving ade- beneﬁts of even a slight increase in PaO2 will out-quate arterial oxygen tension despite pulmonary weigh the theoretical adverse effects of inspiringatelectasis. The effects of HPV are enhanced by the 100% O2, such as O2 toxicity. The dependent lung isinﬂuence of gravity in the lateral decubitus position. ventilated with a tidal volume of about 10 ml kgϪ1Cross-clamping the vessels of the non-ventilated lung body weight and with a respiratory rate sufﬁcient towill completely abolish shunt perfusion and increase maintain partial pressure of arterial CO2 (PaCO2)arterial oxygen tension. near 40 mmHg.Most volatile anaesthetics have been shown to impair If hypoxia persists, the next step is to applyHPV and to cause arterial desaturation in an experi- 5–10 cmH2O of CPAP to the non-ventilated lung.mental setting.62–65 In an elegant study using perfusion This is the single, most effective measure to improvescans and separate lung ventilation with a double- arterial oxygenation and can substantially increaselumen endotracheal tube, Bjertnæs showed that arterial oxygen tension.74 Continuous pressure main-halothane inhibited HPV in humans in clinically rele- tains airway patency in the non-ventilated lung, coun-vant concentrations.66 This effect is difﬁcult to demon- teracts the development of atelectasis to a certain extent,strate in patients undergoing thoracic surgery due to and allows a degree of apnoeic oxygenation of thethe confounding effects of the anaesthetic on the cir- blood still perfusing this lung. Clinical studies haveculation, but studies seem to indicate that isoﬂurane shown that this does not interfere with the progress ofhas less effect on arterial oxygenation and HPV than surgery.other volatiles.67,68 Propofol and opioids have no effecton HPV or oxygenation,69–72 in fact, propofol might The FRC is also decreased in the dependent lungeven enhance HPV.73 Yet, strangely enough, many during OLV in the lateral decubitus position, and aauthors still recommend inhalational anaesthesia as certain amount of venous blood will ﬂow around non-the anaesthetic of choice for thoracoscopic surgery, ventilated alveoli and add to the total amount of
M I N I M A L L Y I N VA S I V E T H O R A C I C S U R G E RY 135venous admixture in the pulmonary veins. One can Preparing the patient for thoracoscopyattempt to increase FRC over closing capacity byapplying positive end-expiratory pressure (PEEP) to The approach to the patient presenting for thoraco-the ventilated lung. When doing this, however, one scopic surgery depends on the nature of the under-must remember that PEEP can compress peri-alveolar lying disease, the planned intervention and the patient’svessels, increasing pulmonary vascular resistance and general clinical condition. Determining the status ofthus diverting blood ﬂow from the ventilated to the the cardiovascular and respiratory systems is thenon-ventilated lung. The positive effects of PEEP anaesthetists’ primary concern, since many thoraco-ventilation of the dependent lung in increasing FRC scopic procedures are performed with the aim ofmight thus be offset by the diversion of blood ﬂow to evaluating and treating diseases of the lungs. The widethe non-ventilated lung with a net increase in total variety of thoracoscopic procedures means that thereshunt perfusion. If fact, this can be observed clinically: will not be a “typical” patient proﬁle. A young adultadding PEEP to the dependent lung can increase or scheduled for treatment of recurrent pneumothoraxdecrease arterial oxygen tension, or have absolutely or a patient with hyperhidrosis scheduled for thoraco-no effect at all. scopic sympathectomy will probably be otherwise healthy and require a different preoperative work-up than an older patient with a long history of smokingThe pragmatic way to proceed is to apply a CPAP of scheduled for thoracoscopic lobectomy. The young5–10 cmH2O with 100% O2 to the non-ventilated patient presenting for thoracoscopic correction oflung. If that is not effective in bringing SaO2 over kyphoscoliosis, on the other hand, might have chronic90%, a PEEP of 5–10 cmH2O is added to the venti- cor pulmonale with severe pulmonary hypertensionlated lung. If SaO2 is still below 90%, then CPAP is and a right ventricle on the verge of decompensation.increased in the non-ventilated lung to 10–15 cmH2O.A further increase in PEEP to between 10 and Preoperative evaluation includes a meticulous history,15 cmH2O is the ﬁnal step in the endeavour to raise physical examination, 12-lead ECG, chest X-ray,SaO2 from potentially hazardous low levels. standard laboratory tests and pulmonary function testing. The latter might include peak ﬂow measure-If none of these measures succeed in bringing the SaO2 ments before and after administering a bronchodilator.to around 90%, one must remember that the fastest The medical history focuses on smoking, occupationaland most successful way to improve oxygenation is to exposure to pulmonary irritants, exercise tolerance,resume two-lung ventilation. One should not hesitate episodes of angina pectoris, paroxysmal episodes ofto remove the cross-clamp and ventilate the non- dyspnoea, muscular weakness, and current and previ-dependent lung if the patient is threatened by severe ous medication. The physical examination might revealhypoxaemia. rhonchi and wheezing, prolonged expiration, engorged jugular veins, cutaneous signs of emphysema or cyanosis. The ECG is useful to detect signs of Practical management of OLV ischaemic or hypertensive heart disease, pre-existing dysrhythmias or intracardial conduction defects, • Insert double-lumen endotracheal tube and verify while the chest radiogram could reveal pulmonary correct position by auscultation and ﬂexible bronchoscopy inﬁltrates, pleural effusions, atelectatic areas, pneumo- thorax, radiolucent areas indicating hyperinﬂation or • Cross-clamp correct connector and disconnect from signs of congestive heart disease. endotracheal tube to allow the lung to collapse. Arterial saturation will fall • If arterial saturation falls below 90%, increase inspira- tory O2 fraction to 1.0 Conditions to look for in patients presenting for • If saturation remains under 90%, add static positive thoracoscopy pressure of 5–10 cmH2O to non-ventilated lung (CPAP) • Coronary artery disease: history, ECG, echocardio- • If saturation is still lower than 90%, add PEEP of graphy 5–10 cmH2O to ventilated lung. Saturation may fall • Obstructive lung disease: history, examination, pul- after PEEP ventilation is started monary function, X-ray • If saturation remains under 90%, sequentially increase • Restrictive lung disease: history, examination, pul- CPAP and PEEP by 5–10 cmH2O monary function, X-ray • If none of these measures are successful in raising • Pulmonary hypertension: auscultation, ECG, echocar- arterial saturation to at least 85–90%, reinstate two- diography lung ventilation • Paraneoplastic syndrome: history, physical examination
136 A N A E S T H E S I A F O R M I N I M A L L Y I N VA S I V E S U R G E RY Figure 9.13 Positioning the(a) patient for thoracoscopy. The amount of tilt of the upper body depends on the intrathoracic location of the surgical site. (a) Patient being prepared for thoracoscopic treatment of recurrent pneumothorax. Note the double-lumen endotracheal tube, the position of the arms and the venous cannulae. (b) Surgery in the anterior medi- astinum. (c) Surgery of the thoracic spine, oesophagus, posterior mediastinum, hilus, etc. (Schematic illustrations by courtesy of Dr Hilmar Dörge, Department of Cardiothoracic(b) (c) Surgery, University of Göttingen.)Anaesthesia Monitoring SaO2 is the single most important parameter duringPositioning the patient OLV, and pulse oximetry is therefore mandatory. Five-For thoracoscopy, the patient is in the lateral decubi- lead ECG, preferably with automated ST segmenttus position with the affected side uppermost. The analysis, capnometry and arterial cannulation forarm on the affected side is ﬂexed at the elbow and invasive blood pressure monitoring and serial bloodabducted to about the level of the ear. The arm of the gas sampling are standard. Depth of relaxation moni-dependent side is either ﬁxed alongside the patient’s toring is useful if continuous neuromuscular block isbody or brought forward in the sagittal plane until it required. Transoesophageal echocardiography (TEE)points directly away from the body (see Chapter 3). might be useful to monitor cardiac function and sur-The patient is often not positioned in the classic lat- gical progress involving the pericardium. If the radialeral decubitus position, but only tilted about 45°, artery is to be cannulated, this should be done in thedepending on the location of the surgical site – anterior elevated arm, since it is usually more easily accessible,or posterior thorax (Figure 9.13). and there is less risk of arterial compression. A large-bore
M I N I M A L L Y I N VA S I V E T H O R A C I C S U R G E RY 137venous cannula is inserted into a vein of the elevated Anaesthesia is induced with a short-acting barbit-arm. A central venous catheter can be introduced urate, propofol or etomidate after an initial injection ofthrough the brachiocephalic vein of either arm or the an opioid (for details see Chapter 5). Neuromuscularjugular vein on the non-dependent side. relaxation is achieved with a non-depolarizing agent of suitable duration. Anaesthesia is maintained with an infusion of propofol, since this does not interfere Essential monitoring for thoracoscopic surgery with HPV (see above), and continuing administration • Pulse oximetry, perhaps with additional serial blood of the opioid. The non-dependent lung is allowed to gas analyses collapse after introduction of the trocars and instru- • Five-lead ECG, preferably with automated ST seg- ments into the pleural cavity. This is done by cross- ment analysis clamping the tube the connecting the ventilator to the • Continuous blood pressure measurement (non- lumen of the double-lumen endotracheal tube sup- invasive or radial artery cannulation) plying the non-dependent lung and disconnecting it • Capnometry altogether (Figure 9.14). Useful additional monitoring Excellent postoperative pain relief can be achieved • Relaxometry with intercostal blocks in addition to intravenous opi- • Temperature oids. If a thoracic epidural catheter was inserted for • TEE anaesthesia, it can be used to great advantage in the postoperative period to reduce intraoperative opioid requirements and provide postoperative analgesia.Induction and maintenance of anaesthesiaBrief diagnostic thoracoscopic procedures can be per-formed safely under local anaesthesi