Written by Sam Parnell
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For out-of-hospital cardiac arrest (OHCA), bag-valve-mask ventilation (BVM-only) and BVM ventilation as a rescue (BVM-rescue) after failed advanced airway placement were associated with improved survival to discharge and neurologically intact survival compared to advanced airway management (AAM, i.e. supraglottic airway or endotracheal intubation). However, given multiple possible confounders, these results should be viewed with caution.
Why does this matter?
The optimal ventilation strategy for patients with out-of-hospital cardiac arrest is controversial. PART and AIRWAYS-2 have recently indicated that supraglottic airways may result in similar or better survival than endotracheal intubation, and observational studies of pediatric and adult patients with OHCA have found improved survival with BVM compared to AAM. However, it remains unclear if these findings are due to differences in patient characteristics of those treated with BVM compared to AAM or the actual benefits of BVM ventilation.
BVM in OHCA – best strategy or just hot air?
This was a secondary analysis of data from the Pragmatic Airway Resuscitation Trial (PART) of nontraumatic adult patients with OHCA treated by several EMS agencies in the U.S. There were 282 BVM-only, 2,129 AAM, and 156 BVM-rescue cases with covariate data. The BVM-only patients had higher field ROSC (37.9% vs. 34.7%), survival to hospital admission (35.8% vs. 24.9%), 72-hour survival (31.6% vs. 14.7%), survival to hospital discharge (28.0% vs. 6.8%), and neurologically intact survival (21.6% vs. 3.6%) compared to patients with AAM.
PART randomized people to either a supraglottic airway or ETT but did not randomize to BVM-only or BVM-rescue. However, a sizable cohort received BVM in some form in a non-random way. BVM-only patients were more likely to have initial shockable rhythms (34.0% vs. 18.6%), EMS-witnessed arrests (21.6% vs. 11.3%), and public location of arrest (21.3% vs. 11.3%) compared to patients with AAM. These different patient characteristics make it difficult to interpret the improved OHCA outcomes for BVM-only patients.
However, an unexpected finding was that BVM-rescue patients had greater survival to discharge (OR = 2.15, 95% CI = 1.17 to 3.95) and neurologically intact survival (OR = 2.64, 95% CI = 1.20 to 5.81) than AAM patients, despite similar initial rates of ROSC. This seems to imply that BVM ventilation may lead to improved OHCA outcomes. Still, without a larger prospective study, a causal relationship cannot be established.
Source
Outcomes With the Use of Bag-Valve-Mask Ventilation During Out-of-hospital Cardiac Arrest in the Pragmatic Airway Resuscitation Trial. Acad Emerg Med. 2020 Mar 27. doi: 10.1111/acem.13927. [Epub ahead of print]
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