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Perioperative management of morbidly obese patient for non geriatric surgery


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Perioperative management of morbidly obese patient for non geriatric surgery

  1. 1. Perioperative management of morbidly obese patient for non bariatric surgery Dr vivek pushp Deptt. of anesthesiology & ccm BRD medical college gorakhpur
  3. 3. OBESITY OBESITY A metabolic disorder that is primarily induced and sustained by an over consumption or under utilization of caloric substrate.  Obesity is a complex multifactorial (genetic,enviorment al,psychological)dise ase 
  4. 4. “Across the globe Obesity become the most common Nutritional disorder and it is second only to smoking as a preventable cause of death. In anesthetic practice it present special challenges for both regional and general anaesthesia”.
  5. 5. INCIDENCE INCIDENCE Worldwide adult population 7%  In Affluent cultures, the poor have the highest prevalence (27% US and 17% UK population)  In Developing world, affluent are at the highest risk.  Obese school children 60-85% 
  6. 6. CAUSES    Genetic predispositio n Sex/ Race/ Economic status Psychological Environment al/ Emotional/ Cultural
  7. 7. Lean Body Mass Formula Lean Body Mass = Body Weight – (Body Weight x Body Fat %) :  Lean body mass is comprised of everything in your body besides body fat.  Your lean body mass includes:  ◦ ◦ ◦ ◦ ◦ organs blood bones muscle skin
  8. 8. Quantifying Obesity Height/ Weight  nomograms  The Broca Index  Body mass Index 
  9. 9. The Broca`s Index  Ideal body weight(IBW) (kg) ◦ For Female = Height (cm) – 105 ◦ For Male = Height (cm) – 100
  10. 10. BMI=Body Weight (kg)/ Height2 (meters) BMI is defined as the patient's weight, measured in kilograms, divided by the square of the patient's height, measured in meters, which yields a measurement bearing the unit kg/m2.  Overweight is defined as a BMI of >25 kg/m2  Obesity as a BMI >30  Extreme obesity (old term "morbid obesity") as a BMI of >40. 
  11. 11. BMI (kgm-2) Definition <18.5 18.5-24.9 25-29.9 30-39.9 40-49.9 Underweight Ideal Weight Overweight Obese Morbidly Obese 50-59.9 60-69.9 >70 Super Obese Super Super Obese Hyper Obese  Other method for quantifying obesity includeSkin fold thickness,Densiometry(under water weighing),DEXA,CT,MRI,Electrical Impedence.
  13. 13. Cardiovascular Changes       Increased blood volume and cardiac output leading to cardiomegaly, left ventricular hypertrophy and a potential for left ventricular failure. Hypertension and ischaemic heart disease Venous access can sometimes be difficult. Thromboembolism risk is increased. The risk of pulmonary embolus and DVT is doubled Venous return is reduced.
  14. 14. Cardiomyopathies  Cardiac failure  Arrhythmias  Sudden cardiac death  Dyslipidaemias  Venous insufficiency  Cerebrovascular disease  Peripheral vascular disease  Atherosclerotic changes 
  15. 15. Respiratory Changes     Reduced compliance (both chest wall and lung), in the airway resistance and reduced FRC will pre-dispose to atelectasis, increased shunt and hypoxia. 70% in work of breathing and a four fold in the Oxygen cost of breathing occur in case of morbid obese. Pulmonary vasoconstriction, pulmonary hypertension and right ventricular hypertrophy. These patients must be pre-oxygenated as they desaturate much quicker than non-obese (3–5 times).decrease in FRC impairs the ability of obese pts to tolerate periods of apnea ,such as during direct laryngoscopy for tracheal intubation.
  16. 16. Pulmonary mechanics:   Inspiratory reserve volume(IRV), expiratory reserve volume(ERV), functional residual capacity(FRC), vital capacity(VC), total lung capacity(TLC) and minute ventilation(MV)( ) but tidal volume(TV) and residual volume(RV) (→). FRC may be below the closing capacity resulting in the small airway closure→ V/P mismatch→ right to left shunting and hypoxemia
  17. 17.  General anesthesia will accentuate these changes such that a 50% decrease in FRC occurs in obese anaesthetised pts compared with a 20% decrease in non obese individuals.. Worsened in: Improved by: ◦ Supine Position PEEP ◦ Trendelenberg position Reverse Trendelenberg Normal Lung volume  Obese, awake Closing volume Functional residual capacity Obese anaesthetized Residual volume
  18. 18. Oxygen consumption and carbon dioxide production are increased.  There is a higher incidence of difficult laryngoscopy and intubation.  The incidence of difficult intubation in morbid obesity is around 13% Altered anatomy:  ◦ ◦ ◦ ◦ ◦ ◦ ◦ Increase in soft tissue Reduced head and neck mobility Large tongue Short neck Large breasts Anterior larynx Restricted mouth opening
  19. 19. Obstructive sleep apnoea- 5% Airflow cessation of >10 secs. and characterised by frequent episodes of apnea or hypopnea during sleep.  RISK FACTORS:  ◦ Large collar size (over 16.5 inches) ◦ Evening alcohol consumption ◦ Pharyngeal abnormalities PATHOPHYSIOLOGY:Passive collapse of the pharyngeal airway during deeper planes of sleep.  CLINICAL FEATURES:  ◦ ◦ ◦ ◦ Snoring and intermittent airway obstruction Resultant hypoxaemia and hypercapnia Arousal and disruption of sleep Daytime somnolence.
  20. 20. Pathophysiology of Sleep Apnea Awake: Small airway + neuromuscular compensation Sleep Onset Hyperventilate: correct hypoxia & hypercapnia Loss of neuromuscular compensation + Airway opens Decreased pharyngeal muscle activity Pharyngeal muscle activity restored Airway collapses Arousal from sleep Apnea Hypoxia & Hypercapnia Increased ventilatory effort
  21. 21. Clinical Consequences Sleep Apnea Sleep Fragmentation Hypoxia/ Hypercapnia Cardiovascular Complications Excessive Daytime Sleepiness Morbidity Mortality
  22. 22. Obstructive Sleep Apnea Hypopnea Syndrome(OSAHS)  5 or more apneic(complete cessation of air flow) events or 15 or more hypopneic(50% reduction of air flow) events per hour of sleep despite of maintaining adequate ventilatory capacity associated with a decrease in SpO2 ≥ 4%.  Regular hypopneic and apneic events → hypoxemia and hypercarbia → rptd stimulation of resp centre → gradual desensitisation of resp centre→ hypoventilation,Hypercapnia ( OHS)  Pickwickian Syndrome is OHS with cor pulmonale. Alveolar
  23. 23. Obesity hypoventilation syndrome (pickwickian syndrome) Loss of the sensitivity to hypercarbia resulting in a combination of hypoxia, Cor Pulmonale and Polycythaemia,respiratory acidosis,pulmonary hypertension,and right ventricular failure.  Diagnosis –Polysomnography (Apnea-Hypopnea index (AHI)), A score of 5-15 is „mild OSA‟, 15-30 „moderate‟, and „severe OSA‟ is over 30  Treatment  ◦ Removal of precipitants ◦ Surgical(uvulopalato pharyngoplasty) ◦ Weight loss ◦ Nocturnal CPAP
  24. 24. Obesity OSA or OHS Increased blood volume Increased cardiac output Hypoxia/hypercarbia LV enlargement Pulmonary arterial hypertension RV enlargement and hypertrophy LV Hypertrophy Hypertension RV failure Pulmonary venous hypertension LV failure Ischaemic heart disease Adams jp murthy PG;obesity in anesthesia and intensive j anaesth 2000;85;91-108
  25. 25.  This presents the anaesthetist with a patient who may be difficult to bag-mask ventilate, difficult to intubate and will desaturate quickly
  26. 26. Anatomic changes affecting the Airway  Deposit of adipose tissue in the lateral pharyngeal walls  Deposit of adipose tissue external to the upper airway  Presence of hypopharyngeal adipose tissue  Presence of pretracheal adipose tissue  Alteration in the shape of the pharynx(long axis of ellipse transverse to ellipse ant- post)  ↓efficiency of the anterior pharyngeal dilator muscles .
  27. 27. Gastrointestinal Changes       Increased acidity and volume of gastric contents. Hiatus hernia and gallstones(due to hypercholestrolemia) are common Increased intra-abdominal pressure. There is a higher risk of regurgitation and aspiration requiring rapid sequence induction if a difficult airway is not anticipated. Fatty infiltration of liver (denoting the duration of obesity) Tracheal extubation should be undertaken with the patient awake
  28. 28. Endocrine Changes There is an association with glucose intolerance.  Hypercholesterolaemia  Hypothyroidism  Cushing syndrome  Insulinoma  tumor involving Hypothalamus  Metabolic Syndrome and  PCOD. 
  29. 29.  “ Morbidly obese individuals have limited mobility and may therefore appear to be asymptomatic even in the presence of significant respiratory and cardiovascular impairment.”
  30. 30. Morphological Changes Positioning  Transferring  Monitoring (arterial line may be needed if NIBP is problematic) 
  31. 31. Surgical and Mechanical Issues Reduced surgical access  Difficult visualisation of underlying structures  Excess bleeding  Longer operating times  Higher risk of infection  Wound infection and wound dehiscence 
  32. 32. OTHERS Gout  Osteoarthritis of weight bearing joints  Back pain  Hepatic impairment/gallstones  Abdominal herniae  Breast and endometrial malignancies 
  33. 33. Preoperative evaluation 
  34. 34.       Detailed history Physical examination Suspect OSA ( h/o- Snoring). Examination of calf muscles for tenderness Examining signs of cardiac failure and diabetes.(Waist-to-hip ratio >1 in women & >0.8 in men increases the risk for IHD, Stroke, Diabetes & Death) Prior anesthetic records should be obtained. ◦ History of previous surgeries ◦ Anesthetic challenges (i.e. ease or difficulty in securing the airway, intravenous access) ◦ Need for ICU admission, Surgical outcomes ◦ Weight of the patient at that time.
  35. 35. The Upper Airway Assessment         Atlanto-occipital joint extension Mallampati classification Temporomandibular joint (TMJ) assessment with interincisor distance Mentohyoid distance Dentition Pretracheal adipose thickness Neck circumference Hypertrophic tonsils and adenoids.
  36. 36. Special attention should be paid to Circulatory, Pulmonary, and Hepatic function
  37. 37. Circulatory evaluation        Signs and symptoms of left or right ventricular failure Classic physical signs of cardiac failure (e.g. sacral edema) may be difficult to identify. History of Hypertension and Diabetes Blood pressures must be taken with the appropriate size cuff. Intravenous and intraarterial access sites should be checked in anticipation of technical difficulties Electrocardiographic abnormalities Echocardiogram
  38. 38. Respiratory evaluation         Smoking history History of hypoventilation and somnolence Pulmonary function tests with spirometry baseline arterial blood gases Chest x-ray Patients with a history of heavy snoring should have a formal sleep study or Polysomnogram (PSG). Severity of obstructive sleep apnea and hypopnea syndrome (OSAHS), apneahypopnea index (AHI) Home Oxygen therapy with continuous positive airway pressure (CPAP) ,response and compliance should be noted.
  39. 39. Hepatic function tests Serum albumin and globulin  Serum aspartate aminotransferase  Serum alanine aminotransferase  Direct and total bilirubin  Alkaline phosphatase  Prothrombin time, and  Cholesterol levels. 
  40. 40. Recommended Preoperative Laboratory Evaluations
  41. 41.  Routine investigations  ECG is mandatory  2D-Echo  CXR  X-ray neck  Baseline ABG(will help evaluate carbon dioxide retention and provide guidelines for perioperative oxygen administration and possible institution of and weaning from postoperative ventilation)  Screening for diabetes  LFT  Lipid Profile  PFT (if needed)  Polysomnogram (if history of heavy snoring)
  42. 42. Preparation Challenges for the Anesthesiologist
  43. 43.          Airway management: Awake fibreoptic intubation Positioning, Monitoring Choice of anesthetic technique and anesthetic agents Pain control Fluid management Consider asking for Assistance. A typical operating table will support 150 kg, but the tilting/tipping may not function. The sphygmomanometer cuff width should be 20% greater than the diameter of the arm Invasive blood pressure monitoring may be required
  44. 44. Dvt Heparin, 5000 IU subcutaneously, administered before surgery and repeated every 12 h until the patient will be fully mobile, or low molecular weight heparins (LMWH) injected subcutaneously 40 mg every 12 h resulted in a decreased incidence of postoperative DVT complications  Stockings, Early mobilization. 
  45. 45. NPO status, and a large bore intravenous access inserted.  An experienced Assistant  The full complement of alternate airway, noninvasive and invasive (e.g. cricothyriodotomy set and surgical tracheotomy set) airway devices should be available. 
  46. 46. Monitors  ECG  NIBP ◦ Cuffs with bladders that encircle ideally of 75% or minimum of 50% of the upper arm circumference should be used  Invasive BP  Pulse oxymetry  EtCO2  Temperature  Neuromuscular monitoring  Central Venous pressure monitoring  Hourly urine output is evaluated to assess fluid balance
  47. 47. Premedication
  48. 48. Preoperative medications  Avoid CNS and respiratory depressants.(sedatives or narcotics).  Antibiotic prophylaxis; increased risk of postoperative wound infection  Anticholinergics(Glyco) if awake intubation is planned.  Aspiration prophylaxis(H2-receptor antagonists and proton pump inhibitors).  Continue antihypertensive medications.  If required O2 supplementation and monitoring.  Premedication should not be given IM as it may be inadvertently administered into adipose tissue leading to unpredictable absorption.
  49. 49. Positioning  Strapping to the operating table in combination with a malleable bean bag  Padding of pressure areas  Special tables for extra load (two tables)  The head up reverse trendelenburg position provides the longest safe apnea period during induction  Lateral tilt to avoid compression of vena cava
  50. 50.  “Stacking” using towels or folded blankets under the shoulders and the head to compensate for the exaggerated flexed position of posterior cervical fat .  The object is to position the patient so that the tip of the chin is at the higher level than the chest to facilitate laryngoscopy and intubation.
  51. 51. Troop Head Elevation Pillow
  52. 52. Anaesthetic management
  53. 53. Intubation technique  Anticipate for difficult airway and prepare in same line  Awake intubation in morbid obese patient LA  DL  Glottis visualized  GA  intubate Not visualized Awake intubation or Awake fiberoptic We should be ready for emergency tracheostomy
  54. 54. Drug handling in obesity Unpredictable Volumes of distribution  Binding  Elimination of drugs  Reduction in total body water  Higher fat mass  Higher lean mass  Higher GFR  Increased renal clearance 
  55. 55. PHARMACOKINETICS OF DRUGS  Drugs are dosed in the morbidly obese on the basis of their lipophilicity.  Highly Lipophilic drugs have increased volume of distribution so drug doses are calculated on the basis of the patients Total Body Weight (TBW). Examples are:         Thiopentone Propofol Benzodiazepines Fentanyl Sufentanyl Succinylcholine Atracurium Cisatracurium
  56. 56.  Weakly lipophilic or lipophobic drugs have unchanged volume of distribution so drug doses are calculated on the basis of the patients lean body weight (LBW). Examples are:  Alfentanil  Ketamine  Vecuronium  Rocuronium  Morphine sulphate  Certain Lipophilic drugs are adminstered according to LBW are Digoxin,Procainamide,Remifentanyl((Vd) remain same).  Calculating initial doses based on LBW with subsequent doses determined by pharmacologic response to the initial dose is a reasonable approach.
  57. 57. Anaesthetic drugs    Insoluble anesthetic gases resistant to metabolic degradation and without lipid depot compartmentalization, combined with rapid return of reflexes are preferred. For intubation muscle relaxants with rapid sequence induction should be used. Succinylcholine and Rocuronium are the available choices. For maintenance of anesthesiaDesflurane/sevoflurane+ Cisatracurium +intravenous infusion of Remifentanyl is prefered.N2O should be avoided particularly in Pt with Pulm HTN.
  58. 58.  Desflurane and Remifentanil infusion are used for maintenance anesthetic because of rapid onset, consistent profile, and rapid offset
  59. 59. Extubation Criteria       Intact neurologic status, fully awake and alert, with head lift greater than 5 seconds Hemodynamic stability Normothermia. The core temperature >36°C. Train-of-four (TOF) reversal documented by peripheral nerve stimulator (T4/T1 >0.9). Full reversal of neuromuscular blocking agents. Respiratory rate (>10 and < 30 breaths/minute)
  60. 60.       Baseline Peripheral Oxygenation, as judged by pulse Oximeter (SPO2 >95% on FIO2 of 0.4). If an arterial line is present, an arterial blood gas may be checked. Acceptable blood-gas results (FIO2 of 0.4: pH, 7.35 to 7.45; PaO2, >80 mm Hg; PaCO2, < 50 mm Hg). Acceptable Respiratory Mechanics: negative inspiratory force (NIF) (>25 to 30 cm H2O; vital capacity (VC) >10 mL/kg IBW; tidal volume (VT) >5 mL/kg ideal body weight [IBW]). Acceptable Pain Control No demonstrated or suspected Laboratory abnormalities
  61. 61. Post-operative Considerations Extubate awake, sitting up.  ICU care, may need CPAP.  Oxygen and oximetry.  Obstructive sleep apnoea is most common some days after surgery.  Adequate analgesia to allow deep breathing/coughing.  Physiotherapy  DVT prophylaxis 
  62. 62. Postoperative analgesia  There is no clear data proving the superiorty of one technique over other for post op analgesia.It depends on type ,site , duration, severity of surgery. Multi Modal Perioperative Analgesia(MMPA) I,e preemptive infiltration local anesthetic at the incision site +NSAIDS+ PCEA(patient controlled epidural analgesia)/PCIA(patient controlled intrathecal analgesia) is a new and advanced method to deal with post op pain.  In certain situation where sedation is to be avoided Dexmedetomidine,Ketorolac,Clonidine,Magnesiu m sulphate are better alternative of Opoids. 
  63. 63. Postoperative complications Postanesthetic hypoxemia Respiratory depression Early ventilatory failure with need for reintubation  Positional ventilatory collapse  Hemodynamic instability  Postoperative nausea and vomiting (PONV)  Venous thromboembolism  Anastomotic leak  Wound infection.   
  64. 64. Regional anesthesia  May be impossible with standard equipment and techniques due to; ◦ Obscured landmarks ◦ Difficult positioning ◦ Extensive layers of adipose tissue ◦
  65. 65. Regional Anaesthesia Engorged extradural veins and extra fat constricting the potential space, less local anaesthetic 7580% of the normal dose is needed for epidurals  Leave extra catheter in the space as it may be subject to drag as the flexed patient relaxes. 
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