Oral Prednisolone in Severe Acute Exacerbation of Chronic Obstructive Pulmonary Disease (COPD)

Inclusion Criteria: * All COPD patients (according to the ATS definition) experiencing acute exacerbation originating in acute respiratory failure and requiring ICU admission will be included in the study. COPD exacerbation is defined by the increased frequency of cough, volume and purulence of sputum and that of wheeze. Acute respiratory failure is defined by the presence of hypercapnia with PaCO2 \>45mmHg associated with pH \> 7.35 and signs of respiratory muscle fatigue (contraction of accessory respiratory muscles, thoracoabdominal swinging ,..). Exclusion Criteria: * Asthmatic patients defined by a reversible obstructive disease following nebulized bronchodilators, * Patients with uncontrolled left heart failure, * AECOPD patients with a radiologically documented pneumonia, * Systemic corticotherapy within 30 days before screening, * contra-indication to corticosteroids (active gastroduodenal ulcer, uncontrolled sepsis, etc. ..)