The patients affected by severe chronic respiratory failure can develop hypercapnic decompensation leading to coma and death in a few hours. At present, the main treatment is noninvasive or invasive ventilation. The noninvasive invasive ventilation requires a minimum of consciousness to insure spontaneous ventilation. In case of noninvasive ventilation impossibility, invasive mechanical ventilation is proposed to patients, which is an aggressive therapy. Regularly, the patients undergo this aggressive therapy without having expressed their opinion. Indeed, a great majority of these patients with severe respiratory insufficiency did not anticipate directives in case of respiratory decompensation (acceptation of aggressive treatments). Efficiency of these aggressive therapies is still uncertain but certainly alters quality of life (discomfort, loss of autonomy…). After complete, clear, loyal and adapted information, a majority of patient do not wish to go on these aggressive therapies. At the time of the decompensation, the patients are incapable to express an opinion because of the hypercapnic narcosis. An extracorporeal CO2 remover device, such as the DECAP CO2, would quickly decrease the hypercapnia what would allow the patient to improve his state of consciousness and so to find the conditions of spontaneous ventilation required for the noninvasive ventilation. The DECAP CO2 device can be used to stop quickly the hypercapnic narcosis and to collect the wills of the patient on the choice of possible aggressive therapies. It is in this last condition that we wish to estimate the DECAP CO2 device.

After validation of the inclusion and exclusion criteria, the patients include in this clinical trial will be randomized between the two arms of the study:

• Noninvasive ventilation alone
• Noninvasive ventilation associated with the DECAP CO2 device

Inclusion Criteria:

Adult patient suffering from severe chronic respiratory failure

• Chronic obstructive pulmonary disease : stage III
• Hypercapnic respiratory decomposition
• No anticipated directive with the treating physician, pulmonologist or his family.
• Challenged for invasive ventilation by critical care doctor, emergency doctor or pulmonologist ; due to the respiratory pathology severity or other (age, comorbidity)
• Not challenged for a noninvasive ventilation
• Failure of the noninvasive ventilation in intensive care unit (pH decrease due to hypercapnia after 2 hours of noninvasive ventilation

Obtaining of the consent of the patient or the reliable person or the close relation

Exclusion Criteria:

• - Patients who made anticipated directives (decision of the patient to have no tracheotomy, intubation, noninvasive ventilation)
• Contraindication to heparin (active bleeding, Heparin-induced thrombocytopenia)
• Patients < 18 years and > 90 years
• Patients already included in another therapeutic trial
• Pregnant woman or breast feeding
• Legal incapacity