SLEEP DISORDERS

Obesity hypoventilation syndrome (OHS) is defi ned by the association of obesity (BMI 30 kg/m 2), daytime hypercapnia (Pa co 2. 45 mm Hg), and var-ious sleep-disordered breathing in the absence of all other causes of alveolar hypoventilation (severe obstructive or restrictive pulmonary diseases, chest wall disorders, neuromuscular diseases). 1-3 Fifteen per-cent of patients with OHS present with pure sleep hypoventilation, whereas up to 85 % of patients with OHS are exhibiting sleep apnea, a disease condition linked with cardiovascular diseases. Furthermore, OHS is characterized by mild hypoxemia during Objective: Open studies suggest that treatment of obesity hypoventilation syndrome (OHS) by noninvasive ventilation (NIV) restores sleep quality and daytime vigilance and reduces cardiovas-cular morbidity. However, to our knowledge no randomized controlled trial (RCT) comparing NIV to conservative measures is available in the fi eld. The goal of this study was to assess i