High Flow Nasal Oxygen Therapy for Hypoxemy After Cardiac Surgery

Inclusion Criteria: * Patient with indication of coronary artery bypass * Absence of preoperative respiratory failure * Hypoxia after extubation defined as SpO2 \< 96% with Venturi mask 50% 8L/min * Age \> 18 years * Signed informed consent Exclusion Criteria: * Patients requiring an imminent intubation, in coma or respiratory exhaustion, in a state of shock or severe rhythm disorders * Hemodynamic instability, low flow rate * Pneumothorax or hemothorax * Bleeding major, ischemic signs * Ventricular arrhythmia * Respiratory failure * Non controlled hyperalgia * Alteration of mental status * Cardiac surgery patients in post-operative valve surgery associated with coronary artery bypass surgery or isolated valve surgery * Pregnancy * Major under guardianship