Table 1 Diagnostic criteria for adverse respiratory events

Upper respiratory tract obstruction requires manual intervention

Mild to moderate hypoxemia (blood oxygen saturation of 90–93%)

Severe hypoxemia (blood oxygen saturation < 90%)

Signs of respiratory distress or respiratory failure (respiratory rate > 20 times /min, with the involvement of accessory respiratory muscle).

Unable to follow instruction to perform deep breathing

Symptoms of upper respiratory muscle weakness (difficulty breathing, swallowing, speaking)

Repeated intubation

Reflux and aspiration after extubation (gastric solute was found in oropharynx)