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Bag-mask ventilation helps to save lives

VentilationAmong critically ill adults undergoing tracheal intubation, patients receiving bag-mask ventilation had higher oxygen saturations and a lower incidence of severe hypoxaemia, found the multi-centre PreVent trials. The authors believe the results have the potential to change practice, ending 50 years of controversy over potentialvomiting of stomach contents into the lungs.

Thousands of Americans die each year during a dangerous two-minute procedure to insert a breathing tube. Now a Vanderbilt University Medical Centre (VUMC) study shows that using bag-mask ventilation, squeezing air from a bag into the mouth for 60 seconds to help patients' breathing, improves outcomes and could potentially save lives.

"When you place a breathing tube, you have to give patients medications to make them relaxed and sleepy. And those medications take about a minute to kick in," said first author Dr Jonathan D Casey, a pulmonary and critical care fellow at VUMC. "After you give those medications, there is a big divide among doctors about whether to just wait and watch while their breathing slows and stops, or to provide ventilation (breath for the patient) with a bag-mask device. We found that providing ventilation with a bag-mask device is safe and very effective. Most importantly, it cut the rate of severely low oxygen levels in half."

Tracheal intubation, the process of placing a breathing tube, may be required to perform surgery or to support breathing during a serious illness. During tracheal intubation for illness, about 40% of people suffer low oxygen levels, which may cause damage to the brain and heart, and 2% of people suffer cardiac arrest, a sudden failure of heart function that is frequently fatal.

The PreVent trial (Preventing Hypoxemia with Manual Ventilation during Endotracheal Intubation) is a multi-centre trial of bag-mask ventilation during tracheal intubation; the results have the potential to change practice across the nation, as more than 1.5m patients undergo tracheal intubation each year in the US.

"Doctors have been performing this procedure for 50 years and there has always been controversy about the safest way to do it," Casey said. "Some doctors believe that when you squeeze the bag and force air into the lungs that will also put air into the stomach and put the patient at risk for vomiting of stomach contents into the lungs.

"That is not what we found. Our study found that bag-mask ventilation didn't cause the vomiting that people were worried about, and it was very effective at preventing low oxygen levels."

The multi-centre trial was conducted in seven ICUs across the US, with adult patients undergoing the procedure receiving either ventilation with a bag-mask device or no ventilation between induction and laryngoscopy. Among the 401 patients enrolled, the lowest median oxygen saturation was 96% in the bag-mask ventilation group as compared to 93% in the no-ventilation group.

A total of 21 patients in the bag-mask ventilation group had severely low oxygen levels, as compared with 45 patients in the no-ventilation group.

Vomiting of stomach contents into the lungs occurred during 2.5% of intubations in the bag-mask ventilation group and during 4% of the group without bag-mask ventilation.

The Medical ICU at Vanderbilt now routinely uses bag-mask ventilation during placement of a breathing tube. "It is important to act on what we learn. Not only did we immediately apply these important results to our practice, but we have started follow-up trials of other ways to improve the safety of tracheal intubation — and those new trials require that bag-mask ventilation be provided for every patient receiving a breathing tube," said Se Matthew W Semler, associate director of the Medical ICU at Vanderbilt and senior author on the study.

"The best thing about this intervention is that it is free," concluded Dr David R Janz, assistant professor of medicine at Louisiana State University and a co-author on the trial. "This is a device that is already always available when you are placing a breathing tube. In the past, we only used the bag-mask device to assist patients' breathing if we had difficulty placing a breathing tube. Now we know that it should be used in every procedure even before we make our first attempt to place a breathing tube."

Abstract
Background: Hypoxemia is the most common complication during tracheal intubation of critically ill adults and may increase the risk of cardiac arrest and death. Whether positive-pressure ventilation with a bag-mask device (bag-mask ventilation) during tracheal intubation of critically ill adults prevents hypoxemia without increasing the risk of aspiration remains controversial.
Methods: In a multicenter, randomized trial conducted in seven intensive care units in the United States, we randomly assigned adults undergoing tracheal intubation to receive either ventilation with a bag-mask device or no ventilation between induction and laryngoscopy. The primary outcome was the lowest oxygen saturation observed during the interval between induction and 2 minutes after tracheal intubation. The secondary outcome was the incidence of severe hypoxemia, defined as an oxygen saturation of less than 80%.
Results: Among the 401 patients enrolled, the median lowest oxygen saturation was 96% (interquartile range, 87 to 99) in the bag-mask ventilation group and 93% (interquartile range, 81 to 99) in the no-ventilation group (P=0.01). A total of 21 patients (10.9%) in the bag-mask ventilation group had severe hypoxemia, as compared with 45 patients (22.8%) in the no-ventilation group (relative risk, 0.48; 95% confidence interval [CI], 0.30 to 0.77). Operator-reported aspiration occurred during 2.5% of intubations in the bag-mask ventilation group and during 4.0% in the no-ventilation group (P=0.41). The incidence of new opacity on chest radiography in the 48 hours after tracheal intubation was 16.4% and 14.8%, respectively (P=0.73).
Conclusions: Among critically ill adults undergoing tracheal intubation, patients receiving bag-mask ventilation had higher oxygen saturations and a lower incidence of severe hypoxemia than those receiving no ventilation.

Authors
Jonathan D Casey, David R Janz, Derek W Russell, Derek J Vonderhaar, Aaron M Joffe, Kevin M Dischert, Ryan M Brown, Aline N Zouk, Swati Gulati, Brent E Heideman, Michael G Lester, Alexandra H Toporek, Itay Bentov, Wesley H Self, Todd W Rice, Matthew W Semler

[link url="http://news.vumc.org/2019/02/18/vumc-study-finds-helping-patients-breathe-during-intubation-prevents-life-threatening-complications/"]Vanderbilt University Medical Centre material[/link]
[link url="https://www.nejm.org/doi/10.1056/NEJMoa1812405"]New England Journal of Medicine abstract[/link]

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