Chronic Obstructive Pulmonary Disease (COPD) patients are more likely to develop acute hypercapnic respiratory failure. In the acute phase, non invasive ventilation has been shown to improve mortality and reduce intubation rate. Few studies are available about long term benefits of home non invasive ventilation in COPD patients with chronic hypercapnic respiratory failure who survived after an acute episode. The purpose of this study is to determine whether home non invasive ventilation can reduce recurrent acute hypercapnic respiratory failure in COPD patients who survived an acute hypercapnic respiratory failure episode treated by non invasive ventilation.

Inclusion Criteria:

• COPD patients who survived after an acute episode of hypercapnic respiratory failure
• patients weaned from ventilation ( non invasive ventilation or mechanical ventilation) prescribed for acute episode since at least five days with following arterial blood gas : pH > 7.35 and PCO2 > = 45 mmHg

Exclusion Criteria:

• severe obstructive sleep apnea ( DI > 30/h)
• Non COPD cause of respiratory failure
• Serious comorbidity
• Adverse psychological status