Current application of high flow oxygen nasal cannula in acute hypoxemic respiratory failure in the emergency department

High flow oxygen with nasal cannula (HFONC) is a relatively new mode of oxygen delivery. Advantages of HFONC versus conventional oxygen therapy (COT) encompass carbon dioxide washout, generation of a slight positive end-expiratory pressure and maintenance of humidified gas flow through airways. These features are mostly shared with non-invasive mechanical ventilation (NIMV), although with lack of a clearly comparable efficacy. In the last few years, HFONC has gained interest as a third alternative to COT and NIMV in the management of acute hypoxemic respiratory failure in the critically ill patient, both in intensive care units and emergency departments. The aim of this article is to review indications, effects and existing evidence on HFONC, COT and NIMV in the setting of acute hypoxemic respiratory failure.