High-flow Nasal Cannula: Mechanisms of Action and Adult and Pediatric Indications

The use of the heated and humidified high-flow nasal cannula has become increasingly popular in the treatment of patients with respiratory failure through all age groups. This article will examine the main mechanisms of actions attributed to the use of the high-flow nasal cannula and review the indications in adult and pediatric populations (outside of the neonatal period). It is unclear which of the mechanisms of action is the most important, but it may depend on the cause of the patient’s respiratory failure. This article describes the mechanism of action in an easy to remember mnemonic (HIFLOW); Heated and humidified, meets Inspiratory demands, increases Functional residual capacity (FRC), Lighter, minimizes Oxygen dilution, and Washout of pharyngeal dead space. We will also examine some of the main indications for its use in both the adult and pediatric age groups. The data for the use of high-flow nasal cannula is growing, and currently, some of the main adult indications include hypoxemic respiratory failure due to pneumonia, post-extubation, pre-oxygenation prior to intubation, acute pulmonary edema, and use in patients who are "do not resuscitate or intubate". The main pediatric indication is in infants with bronchiolitis, but other indications are being studied, such as its use in asthma, croup, pneumonia, transport of a critically ill child, and post-extubation.