Characteristics and Outcomes of Patients Admitted to ICU for a Severe Acute Exacerbation of COPD.

Inclusion Criteria: 1. Age ≥ 40 years old 2. COPD documented or strongly suspected * Chronic respiratory symptoms (dyspnoea, cough and/or sputum) * Exposure to a known risk factor for COPD (such as tobacco smoke) * If available, respiratory function tests showing non- or partially reversible obstructive syndrom (post-bronchodilator ratio FEV1/CV \< 0.7) 3. Severe acute exacerbation, defined as a worsening of the patient's usual respiratory symptoms with signs of acute respiratory distress (polypnoea ≥ 30 cycles.min-1 or use of accessory respiratory muscles) and/or hypercapnic acidosis (with PaCO2 ≥ 45 mmHg and pH ≤ 7.35) 4. Admission to an ICU, a step-up unit or a respiratory care unit Exclusion Criteria: 1. Known asthma (according to the criteria of the international "Global initiative for asthma" guidelines) 2. Patient refusal to participate (information note, application for non-opposition)