Topics in Lung Disease: Obesity-Hypoventilation Syndrome.

Obesity-hypoventilation syndrome is characterized by daytime hypercapnia (arterial partial pressure of carbon dioxide of 45 mm Hg or more) in a patient with a body mass index of 30 kg/m2 or more, in the absence of alternative causes of hypoventilation. It should be suspected in patients with obesity who have daytime somnolence, dyspnea, fatigue, snoring, apnea, and sleep-related and daytime hypoxemia. The diagnosis is confirmed with overnight polysomnography. Additional tests such as measurement of arterial blood gases, serum bicarbonate, and arterial oxygen saturation can further support the diagnosis. Patients with obesity-hypoventilation syndrome have higher rates of intensive care unit admission and health risks; therefore, early diagnosis and specialist referral are crucial to reduce morbidity and mortality. Management includes weight loss (eg, through a comprehensive weight loss pro-gram or bariatric surgery) and positive airway pressure therapy (eg, continuous or bilevel positive airway pressure) to address hypercapnia and concurrent sleep-disordered breathing, if present.