Efficacy of Nasal Cannula Oxygen as a Preoxygenation Adjunct in Emergency Airway Management

Study objective: Although 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. Methods: We 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/mind-oxygen through nasal cannula at 10 L/min, and oxygen through mask at 15 L/min-Foxygen through nasal cannula at 10 L/min with standardized leak. The primaryoutcome was single-breath exhalation end-tidal oxygen (Ero(2)). We compared Ero(2) between preoxygenation modalities, using nonparametric techniques. Results: We enrolled 60 subjects (30 nonrebreather face mask and 30 bag-valve-mask). In scenarios without a mask leak, Ero(2) was similar between bag-valve-mask and bag-valve-mask-Enasal cannula (mean 79% versus 75%; difference -3%; 95% confidence interval [Cl] -8% to 1%). In bag-valve-mask scenarios with a mask leak, Ero2 was higher for bag-valve-mask-Enasal cannula than bag-valve-mask alone (mean 66% versus 41%; difference 25%; 95% Cl 21% to 29%). Ero2 was higher for nonrebreather face mask+nasal cannula than nonrebreather face mask (mean 67% versus 52%; difference 15%; 95% Cl 12% to 18%). In nonrebreather face mask scenarios with a mask leak, Ero2 was higher for nonrebreather face mask-Enasal cannula than nonrebreather face mask (mean 65% versus 48%; difference 17%; 95% CI 13% to 20%). Conclusion: Although 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.