• Clare Hayes-Bradley, Anthony Lewis, Brian Burns, and Matt Miller.
• Retrieval Medicine, Greater Sydney Area Helicopter Emergency Medical Service, New South Wales Ambulance, Australia. Electronic address: clarehayesbradley@yahoo.com.
• Ann Emerg Med. 2016 Aug 1; 68 (2): 174-80.

Study ObjectiveAlthough preoxygenation for emergency airway management is usually performed with nonrebreather face masks or bag-valve-mask devices, some clinicians also deliver supplemental high-flow oxygen by nasal cannula. We aim to measure the efficacy of supplemental nasal cannula oxygen delivery to conventional bag-valve-mask and nonrebreather face mask preoxygenation both with and without a simulated face mask leak.MethodsWe conducted a randomized crossover trial using healthy volunteers. We randomized subjects to preoxygenation with bag-valve-mask or nonrebreather face mask. In random sequence, subjects underwent 3-minute trials of preoxygenation with oxygen through mask alone at 15 L/min, oxygen through mask at 15 L/min with standardized leak, oxygen through mask at 15 L/min+oxygen through nasal cannula at 10 L/min, and oxygen through mask at 15 L/min+oxygen through nasal cannula at 10 L/min with standardized leak. The primary outcome was single-breath exhalation end-tidal oxygen (eto2). We compared eto2 between preoxygenation modalities, using nonparametric techniques.ResultsWe enrolled 60 subjects (30 nonrebreather face mask and 30 bag-valve-mask). In scenarios without a mask leak, eto2 was similar between bag-valve-mask and bag-valve-mask+nasal cannula (mean 79% versus 75%; difference -3%; 95% confidence interval [CI] -8% to 1%). In bag-valve-mask scenarios with a mask leak, eto2 was higher for bag-valve-mask+nasal cannula than bag-valve-mask alone (mean 66% versus 41%; difference 25%; 95% CI 21% to 29%). eto2 was higher for nonrebreather face mask+nasal cannula than nonrebreather face mask (mean 67% versus 52%; difference 15%; 95% CI 12% to 18%). In nonrebreather face mask scenarios with a mask leak, eto2 was higher for nonrebreather face mask+nasal cannula than nonrebreather face mask (mean 65% versus 48%; difference 17%; 95% CI 13% to 20%).ConclusionAlthough not aiding bag-valve-mask preoxygenation with a good mask seal, supplemental nasal cannula oxygen improved preoxygenation efficacy in the presence of a bag-valve-mask mask leak. Supplemental nasal cannula oxygen improved nonrebreather face mask preoxygenation both with and without a mask leak. Supplemental nasal cannula oxygen may be helpful for preoxygenation before emergency airway management.Copyright © 2015 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

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