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Bag-mask ventilation during intubation reduces severe hypoxemia

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Bag-mask ventilation not harmful, but is it beneficial?

Debate around the question of whether to use bag-mask ventilation in critically-ill patients has been limited by the lack of high-quality evidence on the risk of aspiration or on the benefits of this approach. This study found no evidence of an increase in the incidence of aspiration, despite using multiple measures to detect it, which provide some reassurance that manual ventilation during tracheal intubation is not likely to cause significant harm.

One significant limitation of this trial, however, is that it did not standardize the preoxygenation strategy across the two groups, so significantly more patients in the bag-mask group received bag-mask ventilation before induction. Median oxygen saturation before induction was the same in the two groups, but this does not rule out the possibility of differences in the arterial pressure of oxygen.

This study may not settle the question of whether to use bag-mask ventilation during tracheal intubation, but it provides strong suggestion that the practice is not harmful.

Patricia A. Kritek, MD, and Andrew M. Luks, MD, are with the division of pulmonary, critical care, and sleep medicine at the University of Washington in Seattle. These comments are adapted from their editorial accompanying the paper by Casey et al. (N Engl J Med. 2019 Feb 18. doi: 10.1056/NEJMe1900708). Dr. Luks declared personal fees from private industry outside the submitted work. Dr. Kritek reported having nothing to disclose.



Jonathan D. Casey, MD, of Vanderbilt University, Nashville, Tenn., and his coauthors wrote that their results suggested for every nine critically ill patients undergoing tracheal intubation, bag-mask ventilation would prevent severe hypoxemia in one patient.

“These findings are important because oxygen saturation is an established endpoint in airway management trials and is a contributing factor to periprocedural cardiac arrest and death,” they wrote.

They noted that there are conflicting guidelines on the use of bag-mask ventilation during tracheal intubation, with some recommending its use for all patients – even those who are not hypoxemic – and others advising their use only for patients with hypoxemia. This study excluded patients who were identified as hypoxemic or in whom bag-mask ventilation was contraindicated.

Despite concerns about bag-mask ventilation increasing the risk the aspiration, the study showed no significant difference between the two groups in the incidence of operator-reported aspiration or the presence of a new opacity on chest radiograph in the 48 hours after intubation.

The authors acknowledged that, given the low incidence of operator-reported aspiration during tracheal intubation, a much larger study would be needed to show whether bag-mask ventilation did increase the risk of aspiration.

“However, our trial provides some reassurance, since the incidence of operator-reported aspiration was numerically lower in the bag-mask ventilation group than in the no-ventilation group,” they wrote.

There were also no significant differences between the two groups in oxygen saturation, fraction of inspired oxygen or positive end-expiratory pressure in the 24 hours after intubation. Bag-mask ventilation was also associated with similar rates of in-hospital mortality, number of ventilator-free days, and days out of the ICU as no-ventilation.

The authors noted that their trial focused on critically-ill patients in the ICU, so the results may not be generalizable to patients in the emergency department or in a prehospital setting.

The study and some authors were supported by the National Institutes of Health. Two authors declared personal fees from the pharmaceutical industry unrelated to the study, and no other conflicts of interest were declared.

SOURCE: Casey J et al. N Engl J Med. 2019 Feb 18. doi: 10.1056/NEJMoa1812405

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