In France, long term Non-Invasive Ventilation (NIV) is a widely used treatment modality in COPD patients with chronic alveolar hypoventilation who have frequent exacerbations. In France, 7000-10000 COPD patients are currently treated with NIV. Recent NIV respirators are fitted with embedded software that provides details on treatment adherence (daily use, number of sessions/day, number of days of use over a given period etc) and on a number of ventilatory parameters measured during treatment (minute ventilation, tidal volume, respiratory rate, leaks, cycles triggered by the patient, etc.).