In our knowledge there is only few data about the cough determinants in mechanically ventilated patients. However some failure of extubation is due to inefficiency cough. In order to determine some determinants of cough, the investigators propose to evaluate systematically different physiological parameters before and after extubation.

In order to evaluate, and identify the cough determinants, the investigators propose a physiological evaluation for each patients who were intubated and mechanically ventilated during at least 72 hours. Indeed inefficacy of cough after extubation is one of the main reason of extubation failure. However there is no any mean to evaluate it simply now.

Inclusion Criteria:

• Patients mechanically ventilated since 72h
• Age > 18 years
• Hospitalized in Intensive care Unit
• In weaning phase - with the classically criteria to be extubated
• Patients who passed the weaning test (T tube test or other)

Exclusion Criteria:

• Hemodynamic instability
• Absence of consent
• No cooperation of the patient
• Hemodynamic instability
• pH < 7,30
• Severe hypoxemia