Obesity Hypoventilation Syndrome

• Awake alveolar hypoventilation in an obese individual that cannot be attributed to other conditions associated with alveolar hypoventilation

Signs and Symptoms

• Symptoms: hypersomnolence, sleep disturbances, symptoms of OSA
• Signs: obesity

Investigation (must meet all 3)

• Obesity (BMI > 30)
• Awake alveolar hypoventilation (PaCO₂ > 45 mmHg)
• Exclusion of alternative causes of hypercapnia and hypoventilation

Management

• Weight loss + CPAP
• May consider BiPAP if CPAP fails to improve symptoms
• Treatment of concurrent OSA if applicable
• May consider bariatric surgery
• Tracheostomy is last resort

Reference: First-Aid for the USMLE step 2 CK (10th Edition)