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Sample Chapter - Basics Of Anesthesia,  6/e by Miller

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    Sample Chapter - Basics Of Anesthesia,  6/e by Miller Sample Chapter - Basics Of Anesthesia, 6/e by Miller Document Transcript

    • Chapter14 CHOICE OF ANESTHETIC TECHNIQUE Ronald D. MillerANESTHETIC TECHNIQUE General Anesthetic Regional Anesthetic Peripheral Nerve Block Monitored Anesthesia Care T he preoperative anesthetic evaluation (see Chapter 13) provides a database with which to make decisions regarding risk assessment and perioperative management. Regardless of the site (dedicated preanesthesia clinic, inpa-PREPARATION FOR ANESTHESIA tient hospital visit, or primary care clinic) and health carePHARMACOECONOMICS provider performing the preoperative evaluation, the final assessment is the responsibility of the anesthesia providerQUESTIONS OF THE DAY rendering the anesthetic care for the patient.1 The anesthe- siologist is ultimately responsible for (1) determining the medical status of the patient, (2) developing a plan of anesthesia care, and (3) reviewing with the patient or a responsible adult the proposed care plan. After review of the patient’s medical history and laboratory and other test results from the patient’s medical record, confirmation by a focused physical examination, and review of the patient’s fasting status, the anesthesia care provider can then select the anesthetic technique. This chapter provides a broad view of the decision-making process necessary for deciding which anesthetic technique to select. The reader of this chapter will be directed to other chapters for details regarding many of the factors involved with selection of an anesthetic technique. ANESTHETIC TECHNIQUE The anesthesia care provider has several options available including (1) general anesthetic, (2) regional anesthetic (see Chapter 17), (3) peripheral nerve block (see Chapter 18), or (4) monitored anesthetic care (MAC). The choice of anesthetic technique (or combination of techniques) should be based on surgical and patient considerations; frequently, more than one anesthetic technique is ap- propriate (Table 14-1). Patient safety (see Chapter 47), the ability of the surgeon to perform the procedure, and patient comfort during and after the procedure are im- portant issues. Intraoperative and postoperative monitor- ing (see Chapter 20) considerations may influence the choice of anesthetic technique. For example, if a rapid190
    • Chapter 14 Choice of Anesthetic Technique the chosen technique would be low in cost, allow early Table 14-1 Considerations That Influence the Choice of Anesthetic Technique transfer or discharge from the postanesthesia care unit (see Chapter 39), optimize postoperative pain control Preference of patient, anesthesiologist, and surgeon (see Chapter 40), and permit optimal operating room effi- Coexisting diseases that may or may not be related to the ciency, including turnover times. The anesthesia provider reason for surgery (e.g., gastroesophageal reflux, diabetes must evaluate the medical condition and unique needs of mellitus, asthma) each patient, select an acceptable anesthetic technique, Site of surgery and make this recommendation to the patient. An informed patient who has an understanding of the Body position of the patient during surgery anesthetic techniques available and the needs for accom- Elective or emergency surgery plishing the surgery is likely to be comfortable with the Likelihood of increased amounts of gastric contents at the anesthetic technique recommended by the anesthesia time of induction of anesthesia provider. Consent for anesthesia requires an informed patient, and “coercion” by the anesthesiologist should Suspected difficult airway management and tracheal not be used to obtain consent for an anesthetic technique intubation that the patient does not desire. On reaching this deci- Duration of surgery or procedure sion, the anesthesiologist should document the relevant Patient age findings, American Society of Anesthesiologists (ASA) classification, anesthetic technique, and a statement not- Anticipated recovery time ing that the patient understands and accepts the plan and Postanesthesia care unit discharge criteria accompanying risks. III General Anestheticpostoperative neurologic evaluation is needed, a general General anesthesia may be initiated by the administrationanesthetic with short-acting anesthetic drugs or a regional of intravenous drugs or inhalation of a volatile anestheticanesthetic may be selected. Conversely, if intraoperative with or without nitrous oxide. The usual handwrittentransesophageal echocardiography is required, a general anesthetic record is progressively being replaced by elec-endotracheal anesthetic will probably be preferred. There tronic anesthetic records, which sometimes are connectedare few circumstances in which a specific anesthetic tech- to a hospital computer system. Paperless, computerizednique may be safer or more efficacious than another tech- medical records are being adopted by increasing numbersnique.2,3 The anesthesia care provider may perform better of medical centers.6with techniques with which they are more experienced.During anesthesia training, learning as many anesthetic INTRAVENOUS INDUCTION OF ANESTHESIAtechniques as possible adds to the ability of anesthesia General anesthesia is usually induced in adult patients byproviders to be as flexible as possible to unique patient the intravenous administration of an anesthetic (propo-needs. fol, thiopental, or etomidate) that produces rapid onset Unpleasant side effects associated with anesthesia may of unconsciousness (see Chapter 9). Then, ventilationinfluence the choice of anesthetic technique. Because the can be sustained via a face mask or a laryngeal mask air-relative levels of safety for different anesthetic tech- way (LMA) may be inserted or a neuromuscular blockingniques are frequently similar, patient satisfaction may drug may be given intravenously to facilitate direct laryn-become the principal determinant of the anesthetic tech- goscopy before tracheal intubation (see Chapter 16).nique selected. Assuming equivalent safety (also see Although a face mask and LMA are important componentsChapter 47), both the anesthesia provider and patient of airway management, they do present challenges. Forare likely to place prime importance on analgesia, fol- example, in some patients with anatomically difficult orallowed by vomiting, nausea, and to a lesser extent, uri- cavities (e.g., edentulous patients), a leak around thenary retention, myalgia, and pruritus. For some patients, mouth or nose can occur.7 Also the LMA should not haveavoiding being awake (see Chapter 46) is the predomi- cuff pressure exceeding 44 mm Hg.8 The intravenousnant concern, perhaps because of anxiety. For these injection of an anesthetic to produce unconsciousnesspatients, even in the absence of pain, the sights, sounds, followed immediately by a neuromuscular blocking drugand smells of the operating or procedure room are an that produces a rapid onset of skeletal muscle paralysisexperience to be avoided.4,5 (succinylcholine, rocuronium) is referred to as “rapid- An ideal anesthetic technique would incorporate opti- sequence” induction of anesthesia (see later discussionmal patient safety and satisfaction, provide excellent for details). Frequently, the patient is breathing oxygenoperating conditions for the surgeon, allow rapid recov- (3 to 5 L/min) via a face mask (preoxygenation) beforeery, and avoid postoperative side effects. In addition, rapid-sequence induction of anesthesia. Administration 191
    • Section III PREOPERATIVE PREPARATION AND INTRAOPERATIVE MANAGEMENTof oxygen (preoxygenation) is intended to replace nitro- Table 14-2 Evidence of a Patent Upper Airway aftergen (denitrogenation) in the patient’s functional residual Induction of Anesthesiacapacity (about 2500 mL of 21% oxygen) with oxygen.This practice should increase the margin of safety during ▪ The upper part of the chest expands and the reservoirperiods of upper airway obstruction or apnea that may bag partially empties during inspiration.accompany induction of anesthesia. In healthy awake ▪ The reservoir bag refills during exhalation.patients, the increase in arterial hemoglobin oxygen ▪ Capnography reveals cyclic waveforms decreasing tosaturation achieved with eight vital capacity breaths of zero during inhalation and a plateau peak (>20 mm Hg)100% oxygen over a period of 60 seconds is similar to during exhalation.that achieved by breathing 100% oxygen for 3 minutes ▪ The pulse oximeter continues to read >95%.at normal tidal volumes.9 Four vital capacity breaths over ▪ Bilateral breath sounds are present.a 30-second period also increases arterial oxygenation,but the time until hemoglobin desaturation is shorterthan in patients breathing oxygen for 3 minutes or taking Monitoring of arterial hemoglobin oxygen saturationeight deep breaths. with a pulse oximeter provides early warning should arterial oxygen desaturation occur during the period ofRapid-Sequence Induction of Anesthesia10 apnea required for tracheal intubation. Proper placementBefore inducing anesthesia of any type, the equipment of the tube in the trachea must be confirmed after directmust be checked to ascertain lack of any defects.11,12 This laryngoscopy (Table 14-2). After tracheal intubation,evaluation especially includes use of equipment that facili- a gastric tube may be inserted through the mouth totates effective airway management (also see Chapter 16).13 decompress the stomach and remove any easily accessi- A typical rapid-sequence induction of anesthesia ble fluid. This orogastric tube should be removed at theincludes preoxygenation and subsequently cricoid pres- conclusion of anesthesia. When gastric suction is neededsure may be applied by an assistant just before the onset postoperatively, normally the tube should be insertedof drug-induced unconsciousness and loss of protective through the nares rather than the mouth.upper airway reflexes. An opioid (e.g., fentanyl, 1 to2 mg/kg IV or its equivalent) is often given 1 to 3 minutes INHALED INDUCTION OF ANESTHESIAbefore administration of a drug to induce anesthesia. The An alternative to rapid-sequence induction of anesthesiaopioid is intended to blunt the subsequent hypertensive is the inhalation of sevoflurane (nonpungent) with orand heart rate responses to direct laryngoscopy and without nitrous oxide.16 Prior administration of a “sleeptracheal intubation and also to initiate possible preemp- dose” of an anesthetic (e.g., propofol) may be used if antive analgesia. Because remifentanil and alfentanil intravenous catheter is in place. Desflurane produces aundergo more rapid blood-brain equilibration than fenta- rapid onset of effect but is not often selected for annyl these opioids may be more reliable in blunting the inhaled induction of anesthesia because of its airway irri-sympathetic nervous system responses evoked by direct tant effects. Inhaled or “mask induction” of anesthesia islaryngoscopy and tracheal intubation.7 most often selected for pediatric patients when prior With the onset of unconsciousness, the patient’s head insertion of a venous catheter is not practical (see Chap-is positioned to provide optimal patency of the upper air- ter 34). Sevoflurane may also be useful when difficultway. Positive-pressure inflation of the patient’s lungs airway management is anticipated because of the absencewith oxygen is then instituted. Direct laryngoscopy for of salivation and preservation of spontaneous breathing.tracheal intubation is initiated only after the onset of The traditional “awake look” in a patient with a suspectedskeletal muscle paralysis (often verified by a peripheral difficult airway, which included titration of intravenousnerve stimulator), which is typically 45 to 120 seconds anesthetics until the patient tolerated direct laryngoscopy,after the intravenous administration of sucinylcholine, has been modified to include spontaneous ventilation of1.0 to 1.5 mg/kg, or rocuronium, 0.6 to 1.2 mg/kg. Rocur- high concentrations of sevoflurane until laryngoscopiconium, 0.6 mg/kg, has slower onset time than succinyl- evaluation is possible.choline. Increasing the dose of rocuronium to 1.0 to 1.2mg/kg creates an onset time similar to that of succinylcho- Characteristics of Inhaled Induction ofline (see Chapter 12). All other muscle relaxants have an Anesthesia with Sevofluraneonset time of 3 to 5 minutes. With experienced anesthesia Loss of consciousness typically occurs within about 1 min-providers, use of neuromuscular blocking drugs (e.g., suc- ute when breathing 8% sevoflurane. Insertion of a LMA cancinylcholine or rocuronium) actually increases the safety usually be achieved within 2 minutes after administeringof endotracheal intubation.14 Yet once again, use of neu- 7% sevoflurane via a face mask. The addition of nitrousromuscular blocking drugs without adequate doses of oxide to the inspired gas mixture usually does not improveanesthetic drugs is a prime cause of “awareness” during the induction of anesthesia sequence. Prior administrationanesthesia (see Chapter 46).15 of benzodiazepines may facilitate an inhaled induction of 192
    • Chapter 14 Choice of Anesthetic Techniqueanesthesia, whereas opioids may complicate this technique produce a desired response, including skeletal muscleby increasing the likelihood of apnea.10 relaxation and prompt awakening. The excessive sympa- A technique for induction of anesthesia with sevoflur- thetic nervous system responses evoked by noxiousane includes priming the circuit (emptying the reservoir stimulation are predictably attenuated by volatile anes-bag and opening the adjustable pressure-limiting [“pop- thetics. Yet, dose-dependent cardiac depression is a majoroff”] valve), dialing the vaporizer setting to 8% while disadvantage of volatile anesthetics (see Chapter 8). Indeed,using a fresh gas flow of 8 L/min, and maintaining this a volatile anesthetic is seldom administered alone butflow for 60 seconds before applying the face mask to the usually in combination with nitrous oxide. Substitution ofpatient. At this point a single breath from end-expiratory nitrous oxide for a portion of the dose of the volatilevolume to maximum inspiration followed by deep breath- anesthetic allows a decrease in the delivered concentrationing typically produces loss of consciousness in 1 minute. of the volatile anesthetic, resulting in less cardiac depres- After an inhaled induction of anesthesia, a depolariz- sion despite the same total dose of anesthetic. Volatileing or nondepolarizing neuromuscular blocking drug is anesthetics may provide an inadequate analgesic effectadministered intravenously to provide the skeletal muscle and be associated with postoperative hepatic dysfunction.relaxation needed to facilitate direct laryngoscopy for In certain instances, neuromuscular blocking drugstracheal intubation. If endotracheal intubation is not can be given to ensure lack of patient movement and per-accomplished, anesthesia can be maintained by inhala- mit a decrease in the delivered concentration of volatiletion via a facemask or LMA. anesthetics. This use of neuromuscular blocking drugs, however, must be in the presence of an adequate doseMAINTENANCE OF ANESTHESIA of anesthetic. In this regard, intraoperative awareness isThe objectives during maintenance of general anesthesia are a recognized risk of minimal concentrations or doses of IIIamnesia, analgesia, skeletal muscle relaxation, and control anesthetic drugs (“light anesthesia”), especially whenof the sympathetic nervous system responses evoked by patient movements are obscured by drug-induced skele-noxious stimulation. These objectives are achieved most tal muscle paralysis (also see Chapter 46).often by the use of a combination of drugs that may include Opioids that generally do not depress the cardiovascu-inhaled or intravenously administered drugs (or both), with lar system are combined most often with nitrous oxideor without neuromuscular blocking drugs. Each drug (see Chapter 10). In patients with normal left ventricularselected should be administered on the basis of a specific function, however, the lack of opioid-induced cardiovas-goal that is relevant to that drug’s known pharmacologic cular depression and the absence of attenuation of sym-effects at therapeutic doses. For example, it is not logical pathetic nervous system reflexes may be manifestedto administer high concentrations of volatile anesthetics to as systemic hypertension. When this occurs, the additionproduce skeletal muscle relaxation when neuromuscular of low concentrations of a volatile anesthetic is oftenblocking drugs are specific for achieving this goal. Likewise, effective in returning arterial blood pressure to anit is not acceptable to obscure skeletal muscle movement by acceptable level. Neuromuscular blocking drugs are oftenadministering excessive amounts of neuromuscular block- necessary, even in the absence of the need for skeletaling drugs because of insufficient doses of anesthetics. The muscle relaxation, because adequate doses of opioidsselective use of drugs for their specific pharmacologic administered in the presence of nitrous oxide are unlikelyeffects permits the anesthesia provider to tailor the anes- to prevent patient movement in response to painful stim-thetic to the patient’s medical condition and any unique ulation. Another disadvantage of intravenously adminis-needs introduced by the surgery. tered anesthetics versus inhaled anesthetics is an inability Despite its lack of potency, nitrous oxide is the most fre- to accurately titrate and maintain a therapeutic concen-quently administered inhaled anesthetic. Typically, nitrous tration of the injected anesthetic. This disadvantage canoxide (50% to 70% inhaled concentration) is administered be offset to some extent by continuous intravenousin combination with a volatile anesthetic or opioid, or both. infusion of the intravenous anesthetic at a rate previ-The partial pressure of an inhaled anesthetic that produces ously determined in other patients to be associated withits pharmacologic effect should be understood. For exam- therapeutic concentrations in blood. Brain function mon-ple, 60% inhaled nitrous oxide administered at sea level itoring (bispectral index, entropy, auditory evoked poten-exerts a partial pressure of 456 mm Hg (60% of the total tials) may be helpful in titrating the dose of inhaled orbarometric pressure of 760 mm Hg). The same inhaled con- injected anesthetic drugs to produce the desired degreecentration of nitrous oxide (or a volatile anesthetic) admi- of central nervous system depression (see Chapter 20).nistered at an altitude where the barometric pressure isless than 760 mm Hg exerts a decreased pharmacologic Regional Anestheticeffect because the partial pressure of the anesthetic thatcan be achieved in the brain is lower. A neuraxial regional anesthetic (spinal, epidural, caudal) Volatile anesthetics have the advantage of high is selected when maintenance of consciousness duringpotency, and their “dose” easily altered and titrated to surgery is desirable (see Chapter 17). Spinal anesthesia 193
    • Section III PREOPERATIVE PREPARATION AND INTRAOPERATIVE MANAGEMENTand epidural anesthesia each have advantages and disad- may be used.2 IVRA provides reliable anesthesia for bothvantages that may make one or the other technique better the upper and lower extremities, although the latter maysuited to a specific patient or surgical procedure. Spinal be more problematic because of the size of the loweranesthesia (1) takes less time to perform, (2) produces a extremities in adults. After the application of a tourni-more rapid onset of better-quality sensory and motor quet and exsanguination of the extremity, lidocaineanesthesia, and (3) is associated with less pain during sur- (0.5%) is commonly administered into a catheter previ-gery. Unlike epidural anesthesia, a continuous spinal ously placed in the involved extremity. Double tourni-technique is rarely used because of postspinal headache quets (distal cuff inflated over the area where localand concern about the proper maintenance of the cathe- anesthetic has infiltrated with time) help ameliorate tour-ter in the subarachnoid space. niquet pain. Intravenous analgesics such as ketorolac The principal advantages of epidural anesthesia are (1) may be useful for treatment of patient discomfort duringa lower risk for post–dural puncture headache, (2) less IVRA. IVRA is more cost-effective than general anesthe-systemic hypotension if epinephrine is not added to the sia or brachial plexus block for outpatient hand surgery.local anesthetic solution, (3) the ability to prolong orextend the anesthesia through an indwelling epidural Peripheral Nerve Blockcatheter, and (4) the option of using the epidural catheterto provide postoperative analgesia. Skeletal muscle relax- A peripheral nerve block is most appropriate as a tech-ation and contraction of the gastrointestinal tract are also nique of anesthesia for superficial operations on theproduced by a regional anesthetic. extremities (see Chapter 18). Advantages of peripheral Patients may have preconceived and erroneous con- nerve blocks include maintenance of consciousnessceptions about regional anesthesia that will require the and the continued presence of protective upper airwayanesthesiologist to reassure them regarding the safety of reflexes. The isolated anesthetic effect produced bythis technique. The only absolute contraindication to a peripheral nerve block is particularly attractive inspinal or epidural anesthesia is when a patient wishes patients with chronic pulmonary disease, severe cardiacanother form of anesthesia. Certain preexisting condi- impairment, or inadequate renal function. For example,tions increase the relative risk of these techniques, and insertion of a vascular shunt in the upper extremity forthe anesthesia provider must balance the perceived bene- hemodialysis in a patient who may have associated pul-fits of this technique before proceeding (Table 14-3). Dis- monary and cardiac disease is often accomplished withadvantages of this anesthetic technique include the anesthesia provided by a peripheral nerve block of theoccasional failure to produce sensory levels of anesthesia brachial plexus. Likewise, avoidance of the need for neu-that are adequate for the surgical stimulus and hypoten- romuscular blocking drugs in this type of patient circum-sion that may accompany the peripheral sympathetic vents the possible prolonged effect produced by thesenervous system blockade produced by the regional anes- drugs in the absence of renal function.thetic, particularly in the presence of hypovolemia. A disadvantage of peripheral nerve block as an anes- A regional anesthetic technique is most often selected thetic technique is the unpredictable attainment of ade-for surgery that involves the lower part of the abdomen quate sensory and motor anesthesia for performance ofor the lower extremities in which the level of sensory the surgery. The success rate of a peripheral nerve blockanesthesia required is associated with minimal sympa- is often related to the frequency with which the anesthe-thetic nervous system blockade.17,18 This should not, sia provider uses this anesthetic technique. Patients musthowever, imply that a general anesthetic is an unaccept- be cooperative for a peripheral nerve block to be effec-able technique for similar types of surgery. tive. For example, acutely intoxicated and agitated For procedures lasting between 20 and 90 minutes, patients are not ideal candidates for a peripheral nerveintravenous regional anesthesia (IVRA, or Bier block) block. The use of ultrasound guidance in regional anes- thesia has become a routine technique and has increased its use for perioperative care.19 Table 14-3 Conditions That May Increase the Risk Associated with Spinal or Epidural Anesthesia Monitored Anesthesia Care Hypovolemia MAC is defined by the American Society of Anesthesiol- Increased intracranial pressure ogists (ASA) as a procedure in which an anesthetic pro- vider is requested or required to provide anesthetic Coagulopathy (thrombocytopenia) services, which include preoperative evaluation, care Sepsis during the procedure, and management after the proce- Infection at the cutaneous puncture site dure.20,21 This responsibility includes (1) diagnosis and treatment of clinical problems during the procedure; (2) Preexisting neurologic disease (e.g., multiple sclerosis) support of vital functions; (3) administration of sedatives, 194
    • Chapter 14 Choice of Anesthetic Techniqueanalgesics, hypnotics, anesthetic drugs, or other medica- Table 14-4 Routine Preparation before Induction oftions as necessary for patient safety; (4) psychological Anesthesia Independent of the Anesthetic Techniquesupport and physical comfort; and (5) provision of other Selectedservices as needed to complete the procedure safely. Thecare of a patient undergoing MAC is held to the same Anesthesia Machine (see Table 15-9)standard as any other anesthetic technique, given that ▪ Attach an anesthetic breathing system with a properlythe level of sedation may progress rapidly, go beyond sized face maskconsciousness, and lead to an “unplanned” general anes- ▪ Occlude the patient end of the anesthetic breathingthetic (specifically defined by the ASA as any instance in system and fill with oxygen from the anesthesiawhich the patient loses consciousness as defined by the machine (“flush valve”) (applying manual pressure to theability to respond purposefully). When this occurs, extra distended reservoir bag checks for leaks in the anestheticcare may be needed in monitoring to prevent airway mis- breathing system and confirms the ability to providehaps such as upper airway obstruction and arterial hy- positive-pressure ventilation of the patient’s lungs withpoxemia, as reflected by the pulse oximeter reading. oxygen) While caring for a patient under MAC, the total dose ▪ Check the anesthetic breathing system valvesof local anesthetic administered by the surgeon and the ▪ Calibrate the oxygen analyzer with air and oxygen andrisk for local anesthetic toxicity must be monitored (see set alarm limitsChapter 11). In addition to monitoring the patient, sup- ▪ Check the carbon dioxide absorbent for color changeplemental oxygen (may not be necessary if pulse oxime- ▪ Check the liquid level of vaporizerster readings are acceptable while breathing room air), ▪ Confirm proper function of the mechanical ventilatortypically by nasal cannula, should be given. In addition ▪ Confirm the availability and function of wall suction IIIto oxygen, anesthetic drugs can be given intravenously ▪ Check the final position of all flowmeter, vaporizer, andto provide anxiolysis (midazolam), sedation (propofol), monitor (visual and audible alarm) settingsand analgesia (remifentanil, ketorolac, ketamine). MonitorsDepending on the patient and the procedure, fulfilling ▪ Blood pressureone or all of these goals (anxiolysis, sedation, and anal- ▪ Pulse oximetrygesia for arthroscopic surgery) may be needed. Opioid ▪ Electrocardiographyadministration during MAC may be useful but also ▪ Capnographyrequires careful monitoring of oxygenation and ventila- Drugstion. Inhaled anesthetics (nitrous oxide, sevoflurane) ▪ Local anesthetic (lidocaine)administered in concentrations below the threshold of ▪ Induction drug (propofol, thiopental, etomidate)loss of consciousness may be useful during surgical infil- ▪ Opioid (fentanyl, sufentanil, alfentanil, remifentanil)tration of local anesthetic solutions, especially for brief ▪ Benzodiazepine (midazolam, diazepam)periods while patients are not tolerating the procedure ▪ Anticholinergic (atropine, glycopyrrolate)because of agitation or inadequate analgesia. MAC may ▪ Sympathomimetic (ephedrine, phenylephrine)facilitate avoidance of side effects (sympatholysis, respi- ▪ Succinylcholineratory depression, delayed emergence) and may be par-ticularly cost effective in comparison to general or ▪ Nondepolarizing neuromuscular blocking drug (rocuronium, vecuronium, cisatracurium, pancuronium)regional anesthetics in the ambulatory care setting. ▪ Anticholinesterase (neostigmine, edrophonium) ▪ Opioid antagonist ▪ Benzodiazepine antagonist PREPARATION FOR ANESTHESIA ▪ Catecholamine to treat an allergic reaction (epinephrine)After the preoperative medication has been given,regional anesthesia may be administered in the preopera- Equipmenttive area. With all other anesthetic techniques, the patient ▪ Intravenous solution and connecting tubingwill be transported to the operating room for induction of ▪ Catheter for vascular cannulationanesthesia (Table 14-4). On arrival in the operating room, ▪ Suction catheterthe patient is identified and the planned surgery recon- ▪ Oral and/or nasal airwayfirmed. In fact, all of the checks performed in the preop- ▪ Laryngeal mask airwayerative area should be reconfirmed in the operating room. ▪ Tracheal tubeThe patient’s medical record, including the nurse’s notes, ▪ Nasogastric tubeshould be consulted by the anesthesia provider to learn of ▪ Temperature probeany unexpected changes in the patient’s medical condi-tion, vital signs, or body temperature and to determinethat the preoperative medication and, if indicated, 195
    • Section III PREOPERATIVE PREPARATION AND INTRAOPERATIVE MANAGEMENTprophylactic antibiotics have been administered. Like- especially airway management has received considerablewise, any laboratory data that have become available attention for at least 40 years. Examination of multiplesince the preoperative visit should be reviewed. reports reflects the increasing safety to patients and skills Initial preparation for anesthesia, regardless of the of anesthesia providers. The Institute of Medicine hastechnique of anesthesia selected, usually begins with complimented anesthesiology for its attention to safetyinsertion of a catheter in a peripheral vein and applica- (see Chapter 47). However, termination of anesthesiation of a blood pressure cuff. This initial preparation and transport of the patient to the postanesthetic caremay be accomplished in a holding area or in the unit (see Chapter 39) can be associated with adverseoperating room. The use of separate rooms (anesthetic events and also needs the same intense attention by theinduction rooms) distinct from the operating room for anesthesia provider as given during the induction ofinduction of anesthesia is not recommended by some anesthesia.22because of the questionable safety of routinely movinganesthetized patients with the necessary attached equip-ment from one area to another. An exception to this rec- PHARMACOECONOMICSommendation may be the performance of peripheralnerve blocks or epidural anesthesia in a holding or pre- The desire for cost containment often leads to recommen-operative area so that the block is in place when the dations that low-cost drugs (antiemetics, intravenousoperating room becomes available. Likewise, an epidural drugs to induce anesthesia, volatile anesthetics, neuromus-catheter for postoperative pain management may be cular blocking drugs) be used in preference to newer, butplaced in the holding area before transport of the patient more expensive, drugs with desirable pharmacologic pro-to the operating room and induction of general anesthe- files.23 The ultimate goal must be to obtain the best resultssia. Monitors such as the pulse oximeter, electrocardio- (low toxicity, rapid awakening, absence of nausea andgram, and peripheral nerve stimulator are also applied vomiting) at the most practical cost A useful method towhile the patient is still awake. Immediately before decrease the cost of volatile anesthetics is the use of lowinduction of anesthesia, baseline vital signs (systemic fresh gas flow (2 L/min) during maintenance of anesthesia.blood pressure, heart rate, cardiac rhythm, arterial hemo-globin oxygen saturation, breathing rate) and thecorresponding time are recorded. QUESTIONS OF THE DAY Regardless of the anesthetic technique selected, theprovider should verify that the anesthesia machine is 1. A patient requires a thorough neurologic evaluationpresent and functional (in certain circumstances such as immediately after surgery. How does this influenceanesthesia for cardioversion, a breathing circuit may suf- the choice of anesthetic technique?fice) and that specific drugs and equipment are always 2. What are the potential advantages of inhaled induc-immediately available (see Table 14-4), including suc- tion of anesthesia compared to intravenous induction?tioning capability, adequate monitoring (systemic blood 3. What are the responsibilities of the anesthesia pro-pressure, electrocardiography, pulse oximetry, capnogra- vider before, during, and after monitored anesthesiaphy, body temperature), airway equipment (appropriately care (MAC)?sized face mask, oral airway, nasal airway, LMA, laryn-goscope with appropriate functional blades), materialsfor venous access, and drugs appropriate for emergency ACKNOWLEDGMENTintravenous induction and resuscitation (induction drugs,neuromuscular blocking drugs, vasopressors, including The editors and publisher would like to thank Dr. Donaldephedrine and phenylephrine). Taylor for contributing a chapter on this topic to the prior Prime emphasis of this chapter is on induction and edition of this work. It has served as the foundation formaintenance of anesthesia. Induction of anesthesia and the current chapter.REFERENCES 1. Practice Advisory for Preoperative anesthesia, and axillary block for 4. 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