The first-line treatment for hypoxemic respiratory failure is oxygen, which is commonly administered by a nasal cannula or a face mask. High-flow nasal cannula (HFNC) oxygen treatment, in which appropriately heated and humidified oxygen is provided at high flow rates of up to 60 L/min, has lately gained popularity. HFNC treatment provides several advantages over standard low-flow oxygen therapy, including lower positive-end expiratory pressure, flushing of anatomical dead space, a greater and more predictable proportion of inspired oxygen, and improved patient tolerance and compliance. 

The majority of the available evidence for its clinical utility comes from its use in neonatal and pediatric settings, but HFNC therapy has also been studied in adults with acute hypoxemic respiratory failure, patients with chronic obstructive pulmonary disease and heart failure, and for preoxygenation before intubation, as well as post-extubation to avoid or treat respiratory failure in high-risk groups. 

There are currently just a few high-quality trials investigating the effects of HFNC treatment in these patient categories, and a number of crucial concerns remain unanswered, making it impossible to make firm recommendations about its usage. Nonetheless, this is an exciting and unique advancement in the realm of respiratory assistance for adult patients suffering from a range of respiratory diseases.