Comparison of Corticosteroids vs Placebo on Duration of Ventilatory Support During Severe Acute Exacerbations of COPD Patients in the ICU

Inclusion Criteria: 1. Patients aged ≥ 40 years 2. Strongly suspected or documented COPD, defined by the presence of the following criterias: * Persistent respiratory symptoms (dyspnoea, chronic cough or sputum) * History of exposure to a risk factor such as tobacco smoke * If available, pulmonary function tests showing airflow limitation not fully reversible (post-bronchodilator ratio of FEV1/ FVC ratio \< 0.7) 3. ACRF, defined by the presence of the two following criteria: * COPD exacerbation defined by a change in the patient baseline respiratory symptoms at least 24 hours and requiring a change in regular respiratory medication * Acute respiratory failure \<24h (polypnea ≥ 30 breaths.min-1 or use of accessory respiratory muscles) requiring ventilatory support, either invasive (implemented because of respiratory distress) or NIV (implemented because of hypercapnic acidosis with PaCO2 ≥ 45 mmHg and pH ≤ 7.35). 4. Admission to an ICU, a step-up unit or a respiratory care unit 5. Inform consent from the patient or his surrogates. In patients who are not able to consent on admission an emergency inclusion procedure will be allowed, with a mandatory delayed consent. 6. Affiliation to (or benefit from) French health insurance system Exclusion Criteria: * Previous diagnostic of asthma, according to "GINA" international guidelines (40) * Recent use of systemic corticosteroids, defined by systemic corticosteroids use in the past 7 days * Contra-indication of systemic corticosteroids treatment: allergy to corticosteroids, uncontrolled severe arterial hypertension, uncontrolled diabetes mellitus, gastro-intestinal ulcer bleeding * Pneumothorax at randomization * Extracorporeal life support (ECMO or ECCO2R) at inclusion * Moribund patient life expectancy \< 3 months * Pregnancy * Patients protected by law * Exclusion period due to other interventional clinical trial enrolment which can influence primary outcome * Previous inclusion in the present study