Obesity 

 

 

Definitions (WHO, NIH)  

 

  • Overweight: BMI ≥25.0 to 29.9 

  • Obesity: BMI ≥30 

  • Obesity class I: BMI of 30.0 to 34.9 

  • Obesity class II: BMI of 35.0 to 39.9

  • Obesity class III (severe obesity, massive obesity): BMI ≥40 

 

 

Considerations 

 

  • Potentially difficult airway 

  • Physiologic changes of obesity:

    • ↓ FRC →  fast desaturation

    • ↑ cardiac demand & output with limited reserve

    • ↑ gastric volume & abdominal pressure → ↑ aspiration risk

    • ↑ postoperative morbidity & mortality (respiratory failure, wound infections, thromboembolism risk) 

  • Co-morbid diseases:

    • Airway: OSA

    • Respiratory: obesity hypoventilation syndrome (OHS), pickwickian syndrome, pulmonary hypertension, restrictive lung disease

    • Cardiac: hypertension, coronary artery disease, left ventricular hypertrophy, biventricular failure 

    • Endocrine: diabetes

    • GI: reflux, non-alcoholic fatty liver disease 

    • Altered pharmacology:

      • Implications for loading vs. steady state infusions (IBW vs TBW)

      • Sensitivity to sedatives & opioids

      • ↓ neuraxial dose may be needed

  • Potential technical difficulties: 

    • Vascular access

    • Monitoring (NIBP)

    • Regional

 

 

Anesthetic Goals 

 

  • Safe airway management; avoid hypoxemia & aspiration

  • Evaluate physiologic impact of obesity on patient

  • Establish whether regional technique is feasible

  • Minimize perioperative complications:

    • Minimize postoperative airway obstruction/hypoventilation (ensure no residual anesthetic, extubate & nurse semi-recumbent, continuous oxygen saturation monitoring postoperatively & effective postoperative analgesia)

    • Avoid thrombotic complications

    • Avoid peripheral nerve injury 

 

 

Potential Conflicts 

 

  • Difficult airway vs. aspiration risk (RSI)

  • OSA vs. opioid requirements postoperatively & difficulty with regional procedures