Hypoxemia, which can lead to cardiac arrest and death, occurs in a high percentage of critically ill patients undergoing tracheal intubation in the ICU. A nearly 50-year debate has surrounded the use of positive-pressure ventilation with a bag-mask device (bag-mask ventilation) during the interval between medication administration and initiation of laryngoscopy. The aim is to prevent hypoxemia without increasing the risk of aspiration, but this practice is controversial, and guidelines differ.

In a multicenter, randomized trial conducted in seven ICUs, researchers compared bag-mask ventilation with no ventilation during tracheal intubation of critically ill adults. A total of 401 patients were enrolled in the trial. Oxygen saturation at the time of enrollment didn't differ significantly between the groups. All patients received an induction medication (a sedative), and most received a neuromuscular blocking agent.

The median lowest oxygen saturation, the primary outcome, was 96% in the bag-mask ventilation group compared with 93% in the group that didn't receive ventilation. Severe hypoxemia (defined as oxygen saturation of less than 80%) was the secondary outcome and occurred in 21 patients receiving bag-mask ventilation compared with 45 receiving no ventilation. The incidence of operator-reported aspiration didn't differ significantly between the groups, nor did the presence of a new opacity on chest radiography in the 48 hours after tracheal intubation.

The nature of this trial prevented it from being blinded. The authors note that they did not examine the use of noninvasive ventilation in lieu of bag-mask ventilation. Also, this trial only involved ICU patients, so the results may not be generalizable to patients who are intubated in the ED or prehospital setting.

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