Study examines effect of delayed defibrillation for CPR
Some EMTs now delay defibrillation to allow for a short period of CPR based on '05 recommendations
Reuters Health Medical News
SYDNEY — It doesn't matter whether or not EMTs do a few minutes' CPR before defibrillation of cardiac-arrest patients, researchers conclude in a meta-analysis that challenge international guidelines.
"The summary estimate of effect from this meta-analysis demonstrated not only a statistically non-significant result, but also a clinically nonsignificant result," Paul M. Simpson of the Ambulance Research Institute in Sydney, Australia, and colleagues noted online May 19 in Resuscitation.
Contrary to traditional practice, some EMTs now delay defibrillation to allow for a short period of CPR based on 2005 recommendations from the International Liaison Committee on Resuscitation. The guidelines followed findings from animals and two observational studies that suggested it would be easier to restore circulation after initial CPR.
"The prudent stance to take for many larger EMS organizations," the researchers add, "may be to maintain current resuscitation practices whether that is immediate or delayed defibrillation, and instead direct what are usually finite training resources and funding into ensuring the awareness and performance of effective CPR with uninterrupted chest compressions."
In a systematic review, Simpson and colleagues identified three randomized controlled trials that compared CPR before and after defibrillation. Each study was required to include between 90 to 180 seconds of initial CPR and to report survival discharge as the primary outcome.
Two studies were Australian and one was Norwegian; none of them found overall differences in survival regardless of whether patients received CPR first or immediate defibrillation. When pooling data from all 658 patients, the odds ratio was 0.94.
In subgroup analyses stratified according to ambulance response time (more or less than five minutes), the pooled results remained insignificant. However, the researchers note that one study did find a significant survival benefit for patients with the higher response times, and that two of the studies were underpowered.
As a result, they conclude, "EMS jurisdictions are justified continuing with current practice using either defibrillation strategy until further evidence becomes available."