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Chapter 79. Bariatric Surgery

Jamey J. Snell, MD

  • Indications: BMI 30–35 kg/m2 if co-morbidities, or BMI >35 kg/m2 if no co-morbidities, after having failed non-surgical therapy
  • Procedures: Roux-en-Y gastric bypass, gastric banding, sleeve gastrectomy, partial gastrectomy, gastroplasty—vast majority performed laparoscopically unless patient too large
  • Weight loss achieved by mechanical (restricted volume) and/or metabolic (malabsorption) mechanisms
  • Know pathophysiologic and pharmacologic implications of obesity (see Chapter 14)
  • Be aware of the anesthesiologist’s role in assisting bariatric surgery and be vigilant regarding monitors and instruments

  • Pre-surgical testing
    • Assess co-morbid conditions of obesity; further work-up as indicated
    • Some institutions allow patient to bring and use own NIPPV device on day of surgery
  • Pre-operative holding
    • History
      • Many patients w/ OSA are undiagnosed (see Chapter 13)
      • If patient uses CPAP at night, obtain settings and have available in PACU. Also have available if highly suspected but not diagnosed
      • Ask about ability to breathe lying flat for induction considerations
      • Ask about GERD symptoms
      • Prior bariatric surgery warrants evaluation for nutritional deficiencies & electrolytes. Determine whether patient is on liquid diet and/or had bowel prep to anticipate hypovolemia
    • Physical examination
      • Assess for potential difficulties w/ vascular access
      • Mallampati ≥ 3, increased neck circumference (>40–60 cm), BMI > 30 highest predictors of difficult intubation
      • Chest auscultation important to determine baseline lung sounds and to assess for pulmonary congestion
    • Labs/Studies
      • Elevated hematocrit and elevated bicarbonate suggestive of chronic hypoxemia and respiratory acidosis from sleep disordered breathing
      • Review EKG and CXR for evidence of cardiomegaly, right heart overload from pulmonary hypertension, or LV dysfunction; Echo if needed. Daytime, awake ABG on room air with evidence of hypoxia and hypercarbia is suggestive of obesity-hypoventilation syndrome (OHS) in addition to OSA, with even greater risk for post-operative respiratory complications
      • Review data pertinent to co-morbidities
    • Discuss plan with patient and surgery team as additional time frequently needed for induction
  • Pre-medication
    • If awake or sedated intubation planned, begin airway topicalization 30 minutes prior and administer glycopyrrolate 0.4 mg IV, as an antisialagogue, 10 minutes prior to surgery
    • Clonidine (2 mcg/kg PO the night before, and 2 hours before induction) has been shown to reduce intraoperative anesthetic and analgesic requirements

  • BP cuff can be placed at wrist on forearm if arm circumference too large to prevent overestimation of blood pressure (inflatable bladder portion should be 80% of limb circumference)
  • Invasive monitors only if co-morbid conditions suggest intolerance of large fluid shifts, decreased pre-load, or hypercarbia
  • Place CVL if unable to obtain adequate peripheral access; usually poor landmarks, use US guidance
  • Neuromuscular monitoring indicated
    • Muscle relaxation required for pneumoperitoneum, via CO2 insufflation, of a sufficient volume (˜3 L) for operative visualization with intra-abdominal pressure limited to <15–18 mm Hg due to impedance of flow through the IVC
    • Frequent discrepancy between surgical assessments of relaxation versus NMB monitor
    • Apply electrodes to facial nerve rather than ulnar/PT (subcutaneous adipose tissue increases electrical resistance)
  • Avoid esophageal stethoscope/temperature probes to prevent accidental incorporation into the stomach by sutures or stapler
  • Orogastric tubes (OGT) may ...

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