Bagging patients for 60 seconds while waiting to intubate dramatically reduces the odds of low oxygen levels without increasing the risk of aspiration, according to a new multicenter randomized ICU study.
The findings, reported February 18 online in The New England Journal of Medicine and released at the Society of Critical Care Medicine’s Annual Congress in San Diego, may help resolve the 50-year-old controversy over the safest way to perform intubation.
While 21 of 193 patients had severely low oxygen levels with bag-mask ventilation between induction and laryngoscopy, 45 of 197 patients experienced severe hypoxemia when ventilation was withheld during that brief period.
Vomiting with aspiration occurred in 2.5 percent of cases where bag-mask ventilation was used versus in 4 percent when the doctors waited for the 60 seconds or so it took for the drugs to kick in.
“People were very surprised by how effective bagging was, cutting the rate of severe hypoxemia in half,” chief author Dr. Jonathan Casey, a pulmonary and critical care fellow at Vanderbilt University Medical Center in Nashville, told Reuters Health in a telephone interview.
“Now we know that it should be used in every procedure even before we make our first attempt to place a breathing tube,” coauthor Dr. David Janz, assistant professor of medicine at Louisiana State University, said in a statement.
“In the eyes of all clinicians managing airways in the ICU, the results of this rigorous, multicenter trial may not settle the question of the safety of bag-mask ventilation during rapid-sequence intubation,” said Drs. Patricia Kritek and Andrew Luks of the University of Washington, Seattle, in a Journal editorial. “However, the findings provide a strong suggestion that the practice is not harmful.”
More than 1.5 million tracheal intubations are performed annually in the United States and about 40 percent of patients suffer low oxygen levels as a result. Two percent experience cardiac arrest during the procedure.
Dr. Casey said the question hadn’t been studied earlier because research done under emergent conditions can be difficult and because “a lot of groups were convinced they knew the answer,” even though they disagreed on what it was.
When the issue comes up in an operating room, where patients are often getting elective procedures and their stomachs are empty, there’s a much lower risk of vomiting anyway, so doctors there thought bagging was safe. In contrast, guidelines for emergency physicians, who were more likely to see patients with full stomachs, “are pretty strong and recommend against doing this unless you have problems,” said Dr. Casey. “So opinion has largely been divided by specialty.”
The study, known as PreVent and conducted at seven ICUs in the United States, found that when bag-mask ventilation was performed, the lowest median oxygen saturation was 96 percent. Without bagging, it was 93 percent.
The difference in rates of aspiration between the two groups was not statistically significant.
“We’re talking about bagging for one minute. We’re talking about squeezing a bag nine times,” said Dr. Casey. “If you bag for many minutes, maybe eventually vomiting would be a problem. The period doesn’t seem to be long enough to cause problems. If there is an effect, it does appear to be small, not the large effect people worry about.”
The study was funded by the Vanderbilt Institute for Clinical and Translational Research.