In 2012, it has announced the availability of the new ventilator (BiPAP- A40), which could offer potential advantages over fixed level pressure support, in particular, in patients with obesity hypoventilation syndrome (OHS). One of the key benefits of the BiPAP A40 is an innovative ventilation mode called AVAPS-AE, which automatically maintains airway patency while delivering the correct level of ventilation each user requires, whatever their body position or sleep stage. AVAPS-AE mode is also aimed to help the clinicians during the initial titration of therapy, while providing long term comfort and assuring therapy compliance. However, studies on the physiologic and clinical effects have not yet been performed. The aim of our singled-blind randomised multicentre controlled trial is to prospectively investigate the effects of BiPAP with the spontaneous/timed (S/T) or the AVAPS-AE ventilation mode over 8 weeks on sleep quality, ventilation pattern, gas exchange, symptoms, body composition, level of physical activity and health-related quality of life in OHS patients.

Efficacy on sleep quality, symptoms, physical activity and quality of life

Inclusion Criteria:

• Man or woman, stable patient with obesity hypoventilation syndrome, naives of non invasive ventilation.
• PaCO2 ≥ 45 mmHg.
• PaO2 < 70 mmHg
• BMI ≥ 30Kg. m2

Exclusion Criteria:

• Chronic obstructive pulmonary disease
• Neuromuscular disease
• Scoliosis
• Cardiac insufficiency
• Significant psychiatric disease
• Sleep apnea syndrome with central apnea index > 10%
• Treatment with benzodiazepines at the inclusion