Does Nasal Cannula Oxygen Improve Preoxygenation?

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: ba…