Post-extubation Nasal Humidified High-flow Oxygen Versus Non-invasive Positive Pressure Ventilation

All patients assigned to the HFNC group will receive HFNC immediately after extubation. Researchers will need to choose the suitable size nasal catheter. The initial airflow will be set to 50 L/min and adjusted according to patient tolerance with an absolute humidity setting to 44 mgH2O/L and the temperature setting to 37 °C.The patient's respiratory rate will be maintained below 30 beats/min or the baseline level before extubation with a SpO2 at 88-92%. HFNC failure is defined as escalation to NIV or invasive mechanical ventilation due to respiratory failure.

All patients assigned to the control group will receive NIV immediately after extubation. Researchers will use a standard oronasal mask to connect the patient to the ventilator. The patients will be on Spontaneous/Timed (S/T) mode, with the initial end-expiratory pressure setting to 4 cmH2O. The pressure level will gradually increase to ensure that the patients can trigger the ventilator with each inhalation. The initial inspiratory pressure will be set at 8 cmH2O and adjusted according to the tidal volume with 6-8 ml/kg and tolerance of patients. The pres- sure level and the fraction of inspiration oxygen will be adjusted in order to maintain the respiratory rate ≤ 30/ min or the baseline level before extubation, a partial pressure of carbon dioxide (PaCO2) at 45-60 mmHg or the last PaCO2 level recorded before extubation, and a pulse oxygen saturation at 88-92%. NIV treatment failure is defined as a return to invasive mechanical ventilation.