What every intensivist should know about using high-flow nasal oxygen for critically ill patients

The most conventional forms of oxygen delivery rely on facemasks, a nasal cannula or nasal prongs. However, the use of these methods is limited by certain drawbacks, including the need for a flow of oxygen higher than 15L/min in case of severe hypoxemia or the dilution of administered oxygen by entrained room air in cases of high inspiratory flow. An alternative to conventional oxygen therapy has received growing attention: heated, humidified, high flow nasal oxygen (HFNO), a technique that can deliver heated and humidified oxygen, with a controlled fraction of inspired oxygen (FiO2), at a maximum flow rate of 60L/min via a nasal cannula. For a decade, the use of HFNO has been considered for patients with hypoxemic de novo acute respiratory failure (ARF). Recent reports suggest that HFNO can also be used to secure intubation and to prevent post-extubation ARF. The purpose of the present review is to provide clinicians with the most recent information on HFNO and to discuss its benefits and risks in its most common indications.