BMV vs ETI for Out-of-Hospital Cardiac Arrest

— Noninferiority of bag-mask ventilation compared to endotracheal intubation inconclusive

Last Updated March 7, 2018
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Cardiac resuscitation by either bag-mask ventilation or endotracheal intubation (ETI) appears to yield similar outcomes in terms of neurologically favorable 28-day survival in patients with out-of-hospital cardiac arrest, according to results of a multicenter, randomized trial published in JAMA.

"Recent international norms have not provided a clear recommendation on the choice of bag-mask ventilation (BMV) versus ETI," wrote Frederic Adnet, MD, PhD, of Avicenne Hospital in Bobigny, France, and colleagues. "Ventilation by mask is purported to possess certain advantages, namely, being easier to initiate, interfering less with cardiac massage, and appearing to be associated with few significant complications."

Action Points

  • Cardiac resuscitation by bag-mask ventilation (BMV) or endotracheal intubation (ETI) appears to yield similar percentages (4.3% and 4.2%) of neurologically favorable outcomes in patients with out-of-hospital cardiac arrest, but results failed to meet prespecified statistical criteria for noninferiority of BMV.
  • Note that survival to hospital admission and survival at day 28 were not significantly different between the BMV versus ETI groups, 29% versus 33% for survival to admission, and 5.4% versus 5.3% for survival at day 28.

To assess for the noninferiority of BMV versus ETI for advanced airway management in terms of 28-day survival with favorable neurological function, 2,043 patients with out-of-hospital cardiac arrest (average age, 65; 32% women) were randomized to receive either initial BMV or ETI from one of 20 emergency medical services centers in France and Belgium between March 2015 and January 2017.

Among the 2,040 patients who completed the trial, 4.3% of those who received BMV had functionally favorable Cerebral Performance Category 1 or 2 status at day 28 compared with 4.2% of those who received ETI (P=0.11 for noninferiority), a difference that did not meet the noninferiority margin of 1%.

Of the parallel-group study's secondary endpoints, the only significant difference was in return of spontaneous circulation, which was noted in 39% of the ETI group compared with 34% of the BMV group (95% CI -8.8% to -0.5%).

Further study is needed, according to the authors. "Although there was a significantly higher rate of return of spontaneous circulation in the ETI group versus the BMV group, overall 28-day survival was not different. This may be related to differences in ventilation-associated complications (hyperoxia, overventilation, and hypotension) between the two randomized groups and these factors would need to be considered in future trials."

Survival to hospital admission and survival at day 28 were not significantly different between the BMV versus ETI groups, at 29% versus 33% for admission (95% CI -7.7% to 0.3%) and 5.4% versus 5.3% for survival at day 28 (95% CI -1.8% to 2.1%).

Controversy along with evidence linking ETI during cardiopulmonary resuscitation (CPR) with increased mortality have led some researchers to consider the potential of BMV as a more-easily implemented, lower-cost approach to airway management outside of hospital.

While previous research has linked ETI during CPR with significant interruptions in cardiac massage, the authors noted that a large randomized study from 2015 "found no effect on survival caused by short interruptions of cardiac massage when 2 manual ventilations occurred between cycles of cardiac massage."

Similarly, their own post-hoc analysis of a small subgroup of 115 patients found no significant difference in chest compression fraction between the two randomized groups. "The greater number of pauses longer than 2 seconds observed in the BMV group was likely the consequence of cardiac massage interrupted by manual ventilation during CPR, with a rhythm of 30:2," they wrote.

The study's direct randomized comparison allowed a clear discrimination of the two techniques' adverse events. Complications that were significantly more frequent in the BMV group compared to the ETI group, respectively, included airway-management difficulty (18% versus 13%, P=0.004), intervention failure (7% versus 2%, P<0.001), and regurgitation of gastric content (15% versus 7.5%, P<0.001).

Despite the skill and experience required for successful intubation relative to BMV, and differences in staffing out-of-hospital teams with physicians in France versus paramedics in the U.S., studies in both France and the U.S. have reported comparable rates of difficult intubation in the out-of-hospital setting of around 10%, which reflects the study's findings. Thus, the group noted and dispelled this study limitation, concluding that "staffing of out-of-hospital teams was not likely to be a determining factor in explaining these results."

Other limitations include the use of ETI in the BMV group either after return of spontaneous circulation or as a result of difficulty with airway management, and lack of comparison of inpatient management after cardiac arrest, which could vary considerably.

In an editorial that accompanied the article, Roger Lewis MD, PhD, and Marianne Gausche-Hill, MD, both of the David Geffen School of Medicine at UCLA in Los Angeles, noted that the study authors "conducted a remarkable trial that established a lower bound of -1.64% for the relative efficacy of BMV to ETI in terms of neurologically favorable survival but failed to demonstrate noninferiority of BMV," which remains unsettled, they added.

"Further, the applicability of these results for patients in emergency medical services systems not routinely staffed by physicians is unclear," the editorialists wrote. "Despite the sample size limitations, these data could prove useful for other investigators in designing future trials to more definitively address the relative efficacy of BMV versus ETI for adults with out-of-hospital cardiac arrest."

  • author['full_name']

    Kate Kneisel is a freelance medical journalist based in Belleville, Ontario.

Disclosures

This work was supported by the Programme Hospitalier de Recherche Clinique 2013 of the French Ministry of Health. The Assistance Publique Hopitaux de Paris (AP-HP).

All authors reported relevant relationships with industry.

Editorialists had no conflicts of interest to disclose.

Primary Source

JAMA

Source Reference: Adnet F, et al "Effect of bag-mask ventilation vs endotracheal intubation during cardiopulmonary resuscitation on neurological outcome after out-of-hospital cardiorespiratory arrest" JAMA 2018; 319: 779-787.

Secondary Source

JAMA

Source Reference: Lewis R, et al "Airway management during out-of-hospital cardiac arrest" JAMA 2018; DOI: 10.1001/jama.2018.0155.