Preoxygenation with noninvasive ventilation reduces hypoxemia during intubation

1. In this randomized controlled trial involving critically ill adults undergoing tracheal intubation, those who were preoxygenated with bilevel-positive airway pressure had a lower incidence of hypoxemia than those who received preoxygenation with an oxygen mask alone.

2. Noninvasive ventilation appeared to have greater benefit among patients with a higher body-mass index.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Hypoxemia occurs in up to twenty percent of tracheal intubations in critically ill patients. Preoxygenation is known to decrease this risk, but the masks typically used for oxygen delivery do not offer ventilatory support. They may allow the infiltration of ambient air, reducing the effective oxygen concentration received by the patient. Noninvasive positive-pressure ventilation delivered through a tight-fitting mask can theoretically address these two shortcomings, but this approach is more time-intensive and may increase the risk of aspiration. This study was designed to directly compare the effects of preoxygenation with noninvasive ventilation versus oxygen masks among critically ill adults undergoing tracheal intubation. It was found that hypoxemia occurred approximately half as frequently among those who received noninvasive ventilation versus those who received an oxygen mask. Cardiac arrest occurred in a lower percentage of patients who received noninvasive ventilation than those who received oxygen masks, and the incidence of aspiration did not differ significantly between the two groups. One limitation of this study was that about twenty percent of patients who underwent screening for trial eligibility were excluded because they required intubation before completing trial procedures. Further, patients who were already receiving positive-pressure ventilation and at increased risk for aspiration were excluded, making results inapplicable to these populations. Overall, this trial demonstrated that preoxygenation with noninvasive ventilation resulted in a lower incidence of hypoxemia than preoxygenation with an oxygen mask.

Click here to read the study in NEJM

In-Depth [randomized controlled trial]: In this multicenter trial, 1,301 critically ill adults undergoing tracheal intubation were randomly assigned in a 1:1 ratio to receive preoxygenation with either noninvasive ventilation or an oxygen mask. Oxygen was delivered at a fraction of inspired oxygen of 100% in the first group and a flow rate of 15 L/min in the second. The primary outcome was hypoxemia between induction of anesthesia and two minutes after intubation. Preoxygenation was carried out for at least three minutes in over 95% of both groups. The primary outcome, oxygen saturation of <85% during the intubation process, occurred in seven of 624 patients (9.1%) in the noninvasive ventilation group and 118 of 637 patients (18.5%) in the oxygen mask group (absolute risk difference, -9.4 percentage points; 95% CI, -13.2 to -5.6; p<0.001). An oxygen saturation of less than 80% was recorded in 39 of 624 patients (6.2%) in the treatment group and 84 of 637 patients (13.2%) in the control group (absolute risk difference, -6.9 percentage points; 95% CI, -10.2 to -3.7); an oxygen saturation of less than 70% was recorded in 15 patients (2.4%) in the treatment group and 36 patients (5.7%) in the control group (absolute risk difference, -3.2 percentage points; 95% CI, -5.4 to -1.1). Cardiac arrest occurred in one of 645 patients (0.2%) in the noninvasive ventilation group and seven of 656 patients (1.1%) in the oxygen mask group (absolute risk difference, -0.9 percentage points; 95% CI, -1.8 to -0.1). Aspiration occurred in six of 645 patients (0.9%) in the noninvasive ventilation group and nine of 656 patients (1.4%) in the oxygen mask group (absolute risk difference, -0.4 percentage points; 95% CI, -1.6 to 0.7). These results showed that, among critically ill patients requiring intubation, noninvasive ventilation may be a superior method for preoxygenation as compared to an oxygen mask.

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