Post-extubation High-flow Nasal Oxygen for Preventing Extubation Failure

Intubated patients recovering from primary acute hypoxemic respiratory failure who have passed a spontaneous breathing trial will be included in the study. Following extubation, patients will be randomized assigned to one of two study groups. Heart rate, breathing rate, median arterial pressure, FiO2, SpO2, and dyspnea and comfort levels will be measured at defined intervals after extubation (basal, 1 hour, 2 hours, 3 hours, 6 hours, 12 hours, 24 hours, and 48 hours). An arterial blood gas test will be performed 60 minutes and 24 hours after extubation. The number of patients fulfilling certain preset criteria regarding extubation failure will be determined. Extubation failure shall be defined as the need for using invasive mechanical ventilation again within two days following extubation based on the criteria below: * Breathing rate over 25 breaths per minute for more than two hours. * Heart rate above 140 beats per minute or with a sustained increase or decrease greater than 20%. * Clinical data showing fatigue of the respiratory muscles or an increase in breathing work. * SaO2 \<90%; PaO2 \<80 mmHg with a FiO2 \> 50%. * Hypercapnia (PaCO2 \>45 mmHg or \>20% compared to the value before extubation) with a pH below 7.33. Patients who do not fulfill the extubation failure criteria after the first 48 hours of admission may receive extra supplementary oxygen through any device (e.g., nasal cannula, face mask, reservoir mask, etc.). Every day, SpO2 will be measured and the moment when the patient reaches SpO2 \>94% with no need for oxygen will be determined.