High-flow nasal cannula and conventional oxygen therapy provided similar benefits in patients with acute respiratory failure, according to a review of a recent meta-analysis, published in the Annals of Emergency Medicine.

Brit Long, MD, and Michael D. April, MD, DPhil, both from the Department of Emergency Medicine at the San Antonio Uniformed Services Health Education Consortium, Fort Sam, Houston, Texas, reviewed a meta-analysis originally conducted by Zhu et al and published in BMC Pulmonary Medicine in 2017.

The authors of the original analysis searched EMBASE, MEDLINE, the Cochrane Library, and Wanfang databases for randomized controlled trials that compared high-flow nasal cannula and convention oxygen therapies in adults with acute respiratory failure. The investigators identified 4 studies involving 703 patients.

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Two of these studies evaluated the use of high-flow nasal cannula for 24 hours or more, and 2 evaluated this use for less than 24 hours. Outcome measures included escalation of respiratory support, intubation, mortality, and transfer to the intensive care unit.

Although the investigators found no difference for the 2 different modes of respiratory support in the random effects model, subgroup analysis revealed that patients treated with high-flow nasal cannula for 24 hours or more experienced a 29% decrease in escalation of respiratory support. However, rates of intubation, mortality, and transfer to the intensive care unit were similar between the 2 groups.

Dr Long and Dr April noted that acute respiratory failure can be life-threatening and that respiratory support, usually by nasal cannula or face mask, is standard treatment. However, both provided limited maximal flow rate. The high-flow nasal cannula provides humidified and heated supplemental oxygen at a maximal flow rate of 60 L/min.

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The meta-analysis is limited by the small number of included studies and by the variation in the criteria for acute respiratory failure among the studies included in the analysis. It is also limited by heterogeneity in a number of other factors, including study setting, patient selection, acute respiratory failure severity, high-flow nasal cannula starting flow, criteria for escalation of respiratory support, and duration of therapy. Dr Long and Dr April also suggested that the high-flow nasal cannula may affect patients with acute respiratory failure with hypoxia differently than those with hypercapnia.

Dr Long and Dr April called for larger studies with similar criteria for acute respiratory failure, high-flow nasal cannula flow rate, and criteria for respiratory support escalation.


Long B, April MD. Is high-flow nasal cannula more effective than conventional oxygen therapy for preventing escalation of respiratory support in patients with acute respiratory failure [published online April 20, 2018]. Ann Emerg Med. doi:10.1016/j.annemergmed.2018.03.011