Authors: Hayes-Bradley C et al., Ann Emerg Med 2015 Dec 31;
Adding nasal cannula to nonrebreather mask or bag-valve-mask preoxygenation improved end-tidal oxygen levels.
Preoxygenation is used to fill the lungs with oxygen and wash out nitrogen before emergency endotracheal intubation. Investigators assessed the contribution of supplemental nasal cannula–delivered oxygen to end-tidal oxygen levels in a randomized crossover trial of 60 healthy volunteers who received either bag-valve-mask or nonrebreather mask ventilation in each of four scenarios: with and without nasal cannula oxygen and with and without mask leak. End-tidal oxygen levels were measured after 3 minutes of preoxygenation.
Oxygenation was not improved by the addition of nasal cannula oxygen to bag-valve-mask ventilation in the absence of mask leak. However, the addition of nasal cannula oxygen did improve oxygenation in the other scenarios: bag-valve-mask with leak (mean end-tidal oxygen, 66% with nasal cannula oxygen vs. 41% without) nonrebreather mask with leak (65% vs. 48%), and nonrebreather mask without leak (67% vs. 52%).
These results support the common practice of adding nasal cannula oxygen to bag-valve-mask or nonrebreather preoxygenation in emergency airway management scenarios.