High-flow Conditioned Oxygen Therapy Versus Non-invasive Ventilation: Prevention of Post-extubation Failure

Inclusion Criteria: * Low Risk Patients: * Any extubated patients after tolerating a spontaneous breathing trial. * High Risk Patients: * Any extubated patients after \>48 hours under mechanical ventilation and any of the following: * \>65 years * cardiac failure as the primary indication of mechanical ventilation * COPD * APACHE II \>12 points the extubation day * BMI \>30 * inability to manage respiratory secretions * 1 failed spontaneous breathing trial * 1 comorbidity * 7 days under mechanical ventilation Exclusion Criteria: * \<18 years * thacheotomized patients * recent facial or cervical trauma/surgery * active gastro-intestinal bleeding * lack of cooperation and patients with any failed spontaneous breathing trial because of hypercapnia development.