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Table 14-1 Obesity Categories Based on the Body Mass Index (BMI)

Physiologic Effects

Table Graphic Jump Location
Table 14-2 Physiologic Effects of Obesity

  • 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




  • 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 ...

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