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Obesity hypoventilation syndrome — SCE Respiratory MCQ

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ModerateSleep MedicineObesity hypoventilation syndromeSCE Respiratory

A 58-year-old woman with BMI 48 kg/m2 has morning headaches, hypersomnolence and ankle oedema. Awake ABG on air shows pH 7.36, PaCO2 7.1 kPa and PaO2 8.3 kPa. Sleep study shows severe OSA with sustained nocturnal hypoventilation. What is the most likely diagnosis?

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Correct answer: A — Obesity hypoventilation syndrome

Obesity with awake hypercapnia and sleep-disordered breathing defines obesity hypoventilation syndrome. Uncomplicated OSA does not cause persistent daytime hypercapnia, and COPD-overlap needs obstructive spirometry or COPD history. PAH and opioid-related central apnoea do not fit the BMI-linked daytime ventilatory failure.

Reference: NICE NG202