Does Maximal Exhalation Decrease Time Required for Preoxygenation?

Preoxygenation is fundamental to emergency airway management using rapid sequence intubation. Of the various techniques that have been promoted to rapidly accomplish preoxygenation, tidal volume breathing and vital capacity breathing (e.g., 4 deep breaths in 30 seconds) have been shown to be effective. Researchers examined the effect of prior maximal exhalation on preoxygenation using these two techniques in 15 healthy volunteers.

All subjects underwent periods of tidal volume breathing and deep breathing, with and without prior maximal exhalation, while wearing a tight-fitting mask and breathing through a controlled anesthesia circuit. The researchers monitored inspired and expired gases and measured the time to a predetermined, expired end…