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The Effect of High-Flow Nasal Cannula Oxygen Therapy on Mortality and Intubation Rate in Acute Respiratory Failure: A Systematic Review and Meta-Analysis

Monro-Somerville, Thalia MBBS; Sim, Malcolm MD; Ruddy, James MBBS; Vilas, Mark MBChB; Gillies, Michael A. MD

doi: 10.1097/CCM.0000000000002091
Online Review Articles

Objective: High-flow nasal cannulae are used in adults with or at risk of acute respiratory failure. We conducted a systematic review and meta-analysis to evaluate the evidence for their use in this setting.

Data Sources: Ovid Medline, Embase, and Cochrane Database of Systematic Reviews.

Study Selection: Databases were searched for randomized controlled trials comparing administration of high-flow nasal cannulae with usual care (i.e., conventional oxygen therapy or noninvasive ventilation) in adults with respiratory failure. The primary outcome was hospital mortality; the rate of intubation and assessment of delirium and comfort were secondary outcomes.

Data Extraction: One hundred forty-seven nonduplicate citations were screened, 32 underwent full screening and data extraction, and 14 trials were eligible for inclusion in the review. Nine trials were used in the meta-analysis, including a total of 2,507 subjects.

Data Synthesis: When high-flow nasal cannulae were compared with usual care, there was no difference in mortality (high-flow nasal cannulae, 60/1,006 [6%] vs usual care, 90/1,106 [8.1%]) (n = 2,112; p = 0.29; I2, 25%; fixed effect model: odds ratio, 0.83; 95% CI, 0.58–1.17) or rate of intubation (high-flow nasal cannulae, 119/1,207 [9.9%] vs usual care, 204/1,300 [15.7%]) (n = 2,507; p = 0.08; I2, 53%; random effect model: odds ratio, 0.63; 95% CI, 0.37–1.06). A qualitative analysis of 13 studies on tolerability and comfort suggested that high-flow nasal cannulae are associated with improved patient comfort and dyspnea scores. Trial sequential analyses on primary and secondary outcomes suggested that required information size was not reached.

Conclusions: No difference in mortality or intubation was detected in patients with acute respiratory failure treated with high-flow nasal cannulae compared with usual care. High-flow nasal cannulae seem well tolerated by patients. Further large randomized controlled trials are required to evaluate their utility in this setting.

Supplemental Digital Content is available in the text.

1Department of Anaesthesia, Critical Care and Pain Medicine, Royal Infirmary of Edinburgh, Edinburgh, United Kingdom.

2Department of Anaesthesia, Critical Care and Pain Medicine, Queen Elizabeth University Hospital, Glasgow, United Kingdom.

3Department of Anaesthesia, Critical Care and Pain Medicine, Monklands General Hospital, Airdrie, United Kingdom.

All authors contributed equally to the study design, study conduct, and preparation of the article. Drs. Monro-Somerville and Gillies take responsibility for the conduct of the study and the integrity of the results. All authors read and approved the final article.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website (

Dr. Monro-Somerville disclosed other support (Drs. Sim and Gillies are Chief Scientist’s Office (Scotland) research fellows). Drs. Monro-Somerville, Sim, and Ruddy have received funding from Fisher-Paykel to attend conferences. Dr. Sim received funding from Fisher and Paykel (no money paid directly to Dr. Sim, but accommodation and travel were organized for speaking at a respiratory CARE conference and for being a delegate at another respiratory care conference). His institution received funding from Fisher and Paykel (manufacturers of a high-flow nasal oxygen device and Scottish Infection Research Network [small grant examining metabolomics in sepsis]). Dr. Ruddy disclosed other support (expenses paid to present at CARE conference). Dr. Gillies’ institution received funding from Chief Scientist’s Office (Scotland). Dr. Vilas disclosed that he does not have any potential conflicts of interest.

Address requests for reprints to: Thalia Monro-Somerville, MBBS, Michael A. Gillies, MD, Department of Anaesthesia, Critical Care and Pain Medicine, Royal Infirmary of Edinburgh, Little France Crescent, Edinburgh, EH16 4SA, United Kingdom. E-mail:;

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