Bag-Mask Ventilation Versus Apneic Oxygenation During Tracheal Intubation in Critically Ill Adults: A Secondary Analysis of 2 Randomized Trials

Abstract

Background: Hypoxemia is common during tracheal intubation in intensive care units. To prevent hypoxemia during intubation, 2 methods of delivering oxygen between induction and laryngoscopy have been proposed: bag-mask ventilation and supplemental oxygen delivered by nasal cannula without ventilation (apneic oxygenation). Whether one of these approaches is more effective for preventing hypoxemia during intubation of critically ill patients is unknown. Methods: We performed a secondary analysis of data from 138 patients enrolled in 2, consecutive randomized trials of airway management in an academic intensive care unit. A total of 61 patients were randomized to receive bag-mask ventilation in a trial comparing bag-mask ventilation to none, and 77 patients were randomized to receive 100% oxygen at 15 L/min by nasal cannula in a trial comparing apneic oxygenation to none. Using multivariable linear regression accounting for age, body mass index, severity of illness, and oxygen saturation at induction, we compared patients assigned to bag-mask ventilation with those assigned to apneic oxygenation regarding lowest oxygen saturations from induction to 2 min after intubation. Results: Patients assigned to bag-mask ventilation and apneic oxygenation were similar at baseline. The median lowest oxygen saturation was 96% (interquartile range [IQR] 89%-100%) in the bag-mask ventilation group and 92% (IQR 84%-99%) in the apneic oxygenation group. After adjustment for prespecified confounders, bag-mask ventilation was associated with a higher lowest oxygen saturation compared to apneic oxygenation (mean difference, 4.2%; 95% confidence interval, 0.7%-7.8%; P = .02). The incidence of severe hypoxemia (oxygen saturation<80%) was 6.6% in the bag-mask ventilation group and 15.6% in the apneic oxygenation group (adjusted odds ratio, 0.33; P = .09). Conclusions: This secondary analysis of patients assigned to bag-mask ventilation and apneic oxygenation during 2 clinical trials suggests that bag-mask ventilation is associated with higher oxygen saturation during intubation compared to apneic oxygenation.

Keywords: critical care; endotracheal intubation; intensive care unit; respiratory failure.

Figure 1.

Lowest oxygen saturation for bag-mask ventilation versus apneic oxygenation. Left panel: A scatterplot of the unadjusted lowest oxygen saturations for all patients included in the bag-mask ventilation and apneic oxygenation groups in the primary analysis. Right panel: the adjusted mean lowest arterial oxygen saturation and 95% confidence interval for patients in the bag-mask ventilation and apneic oxygenation. The adjusted mean lowest oxygen saturation is adjusted to the median of the remaining model covariates: age of 60 years, BMI of 28.4 kg/m², and APACHE II score of 21. Abbreviations: BMV, bag-mask ventilation; AO, apneic oxygenation; APACHE II, Acute Physiology and Chronic Health Evaluation; BMI, body mass index.

Figure 2.

Heterogeneity of treatment effect by oxygen saturation at induction. The adjusted mean and 95% confidence interval for lowest arterial oxygen saturation is displayed for patients who received bag-mask ventilation (blue) and apneic oxygenation (red) across a range of oxygen saturations at induction. This partial effect plot represents how oxygen saturation at induction potentially modifies the effect of bag-mask ventilation on lowest oxygen saturation. Predictions are adjusted to the median of the remaining model covariates: age of 60 years, BMI of 28.4 kg/m², and APACHE II score of 21. Abbreviations: APACHE II, Acute Physiology and Chronic Health Evaluation; BMI, body mass index.