Extubation Failure Prevention in High Risk Patients by High-flow Conditioned Oxygen Therapy vs. Standard Oxygen Therapy

Inclusion Criteria: * Patients mechanically ventilated for \> 48 hours and at least one of the following: * \>65 years * cardiac failure as the primary indication of mechanical ventilation * Chronic Obstructive Pulmonary Disease * Severity score (APACHE II \>12 points) the extubation day * Body Mass Index \>30 * inability to manage respiratory secretions * 1 failed spontaneous breathing trial * 1 comorbidity * 7 days under mechanical ventilation Exclusion Criteria: * \<18 years * tracheotomized patients * recent facial or cervical trauma/surgery * active gastro-intestinal bleeding * lack of cooperation * patients with any failed spontaneous breathing trial because of hypercapnia development.