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Obesity hypoventilation syndrome — SCE Respiratory MCQ

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ModerateSleep medicineObesity hypoventilation syndromeSCE Respiratory

A 58-year-old man with BMI 48 kg/m² presents with morning headaches, ankle swelling and daytime somnolence. SpO2 is 89% on air and ABG shows pH 7.36, PaCO2 7.2 kPa, PaO2 7.4 kPa and HCO3− 33 mmol/L. Overnight oximetry shows prolonged desaturation, and spirometry excludes severe COPD. He has no acute infection. What is the most likely diagnosis?

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Correct answer: B — Obesity hypoventilation syndrome

Daytime hypercapnia in severe obesity with sleep-disordered breathing and exclusion of other causes supports obesity hypoventilation syndrome. Uncomplicated OSA does not cause persistent daytime hypercapnia. OHS carries cardiopulmonary risk and often needs positive airway pressure plus weight-management intervention.

Reference: NICE NG202 OSAHS/OHS; BTS/ICS acute hypercapnic respiratory failure guideline