Q: What added benefit high flow nasal cannula oxygen provides beside relief of hypoxemia?

Answer: High flow oxygen (HFO) therapy via high flow nasal cannula (HFNC) serves many purposes. It is a very effective therapy in preventing invasive ventilation while clinicians work on treating underling causes of impending respiratory failure. It not only improve oxygenation or decrease the work of breathing, but also decreases atelectasis and counteracts intrinsic PEEP. In HFNC, gas inlet flow prevents secondary room-air entrainment, provides anatomic oxygen reservoirs using nasopharynx and oropharynx and washes out airway dead spaces.

References:

1. Parke R, McGuinness S, Eccleston M. Nasal high-flow therapy delivers low level positive airway pressure. Br J Anaesth. 2009;103(6):886-90.

2. Kernick J, Magarey J. What is the evidence for the use of high flow nasal cannula oxygen in adult patients admitted to critical care units? A systematic review. Aust Crit Care. 2010;23(2):53-70.