Chapter 14. Obesity

Classification

Physiologic Effects

• Focused history and physical examination to detect and to assess the severity of any obesity-related comorbidities:
  • Exercise tolerance, CAD, HTN, NIDDM, cardiomyopathy
  • Presence of snoring at night (may suggest undiagnosed hypoventilation syndrome); formal diagnosis of OSA not needed: in doubt, treat as such
  • Assess for difficult airway and prepare specialized airway equipment as necessary (i.e., awake fiber-optic):
    • Assess for difficult mask ventilation (morbid obesity with redundant tissue, OSA, beard, edentulous)
    • Special focus on:
      • Mallampati class
      • TM distance
      • Neck range of motion
      • Size of tongue
      • Redundancy of soft tissue in and around airway
      • Neck circumference at the level of thyroid cartilage >60 cm2
• Elicit history of past diet medication use (fenfluramine with risk of valve thickening and pulmonary hypertension, amphetamines)
• Chem 7, CBC (polycythemia), EKG, and CXR (cardiomyopathy); consider TTE (although often poor quality)
• Ensure medical equipment appropriately sized (e.g., blood pressure cuff)
• OR table certified for patient’s weight (if needed, use special table, or two tables)
• Ensure personnel available for positioning
• Consider aspiration prophylaxis
• Discuss increased anesthetic risk with patient

Induction

• Vascular access:
  • Potentially very difficult; consider use of ultrasound
• Preoxygenation:
  • Decreased FRC leads to rapid desaturation during even brief periods of apnea
• Mask ventilation:
  • May be difficult/impossible
  • Use two-person mask, oral airway, head strap
  • Use head of bed elevation, CPAP
• Intubation:
  • Position in head-elevated laryngoscopy position (HELP) using pillows/towels: align tragus with sternum (Figure 14-1)
  • Large chest may necessitate use of short-handle laryngoscope
  • Advanced airway techniques/rescue devices (e.g., video laryngoscopy, LMA) should be ...