The main aim is to demonstrate whether the high flow conditioned oxygen therapy reduces the reintubation rate. Post-extubation respiratory failure risk will be stratified (as the randomization). In high risk patients high flow conditioned oxygen therapy will be compared with with not conditioned non-invasive mechanical ventilation. In low risk patients comparison will be conventional oxygen therapy. Hypercapnic patients will be excluded.

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.