High-flow nasal cannula oxygen therapy: more than a higher amount of oxygen delivery

The process of disconnecting critically ill patients from the respirator is a crucial step of patients care (1). Weaning can be initiated when stable patients have recovered enough to tolerate a spontaneous breathing trial (SBT). This requires daily identification of patients with an acceptable P/F ratio obtained with no more than 40–50% of inspiratory of oxygen, a low level of PEP (no more than 5 cm of water), hemodynamic stability (no or minimal regimen of intravenous vasopressors, no more than 5 µg/kg/min of dobutamine), and a neurologic status likely to allow spontaneous breathing (no or minimal sedation, ability to cough, absence of copious secretion) (2,3). The necessity to start SBT only in patients with a low temperature (<38 ℃) is less consensual. In patients with these criteria, a SBT of variable duration (30 to 120 mn) is performed, with different modalities (T tube, low level pressure support with or without additional low level of PEP). Some practical advantages of using pressure support in this situation (accurate monitoring of tidal volume, respiratory rate and prevention of tube occlusion) may explain why some intensivists favor this modality. At the end of a successful SBT, airways patency could be assessed by the qualitative or quantitative detection of a leak around the tube whose cuff has been deflated. When no or minimal leak is observed, extubation is postponed, and prophylactic intravenous steroids administered for no more than 24 hours could decrease the risk of post extubation stridor (1). Following this strategy the patient is extubated.