BMC: Meta-analysis supports chest compressions before defibrillation

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Overall, there were no significant differences in outcomes in patients suffering out-of-hospital cardiac arrest (OHCA) when initially given either chest compressions or defibrillation. However, subgroup analyses showed a trend toward superiority of chest compressions when emergency response time was greater than five minutes, according to a meta-analysis published Sept. 9 in BMC Medicine.

Current guidelines of the European Resuscitation Council and the American Heart Association (AHA), last updated in 2005, emphasize the importance of early defibrillation for OHCA. The AHA does allow chest compressions first in cases of nonwitnessed events (class IIb recommendation). In addition, small clinical and preclinical studies have suggested the superiority of delivering chest compressions first before defibrillation.

To help clarify these data, Pascal Meier, MD, from the division of cardiovascular medicine at University of Michigan Medical Center in Ann Arbor, Michigan, and colleagues from various international facilities identified four randomized, controlled clinical trials published between Jan. 1, 1950, and June 19, 2010, enrolling 1,503 subjects to compare the two approaches.

"This is the first meta-analysis to systematically review the current research on chest compressions first compared to defibrillation first on outcomes in patients with OHCA," researchers wrote.

The investigators found no significant difference between the chest compression-first versus defibrillation-first approach regarding the primary endpoint (survival to hospital discharge) or the secondary endpoints (return of spontaneous circulation and favorable neurologic outcomes).

Regarding the secondary endpoint of long-term survival, researchers found a favorable trend for chest compressions first, but the "95 percent confidence interval crossed 1.0, suggesting insufficient estimate precision."

Additionally, there was a favorable trend for chest compression-first for the primary and secondary endpoints when the EMS response time was greater than five minutes. Conversely, defibrillation-first was favored when response time was under five minutes. Again, however, the 95 percent confidence interval crossed 1.0, making theses differences not statistically significant.

"Current evidence does not support the notion that chest compression first prior to defibrillation improves the outcome of patients in out-of-hospital cardiac arrest. It appears that both treatments are equivalent. However, subgroup analyses indicate that chest compression first may be beneficial for cardiac arrests with a prolonged response time," the researchers concluded.

"The implications are that chest compressions really matter and that we need to make a stronger emphasis to the community to perform chest compressions," said senior author Comilla Sasson, MD, formerly with the University of Michigan and now with the University of Colorado in Denver, in an interview.

The AHA will be updating CPR guidelines later this year, Sasson said. "Hopefully, with this meta-analysis and other work being done, the new guidelines will place a greater importance on chest compressions."