JEMS.com is excited to give you an advance look at a noteworthy new article set to appear inResuscitation, (Edelson DP, Abella BS, Kramer-Johansen J, et al: "Shallow chest compressions and long pre-shock pauses predict defibrillation failure during cardiac arrest." Resuscitation. 2006; in press).
Dana Peres Edelson, MD, lead author of the prospective, multi-center, observational study of adult in-hospital and out-of-hospital cardiac resuscitations conducted between March 2002 and December 2005, has also given JEMS.com an exclusive perspective on the potential implications of the study and its findings against the backdrop of an ever-increasing need to measure and ensure the quality of CPR in the prehospital arena.
How would you sum up the major findings of your article?
Edelson: We found that CPR quality in the time preceding defibrillation is correlated with defibrillation outcomes. Specifically, the longer the pre-shock pause in chest compressions and the shallower the chest compressions immediately preceding defibrillation, the less likely a defibrillation attempt is to be successful in converting a patient out of ventricular fibrillation.
Why was the study undertaken?
Edelson: Several studies in animal models have shown that prolonged pre-shock pauses correlate with worse outcomes, but little data existed in human subjects.
What are your thoughts on the potential/actual impact of the findings on prehospital care?
Edelson: The impact of this study is likely twofold. First, automated external defibrillators (AEDs) vary greatly in the amount of time that they require to analyze and administer a shock during which no chest compressions can be administered. This translates into prolonged pre-shock pauses (greater than ten seconds) in most AEDs in circulation. If we are to believe that these pauses are detrimental, then many of today's AEDs may be offsetting the benefit of early defibrillation with prolonged pre-shock pauses and may be one of the reasons that we haven't see more benefit from the widespread availability of AEDs.
The other important implication for this study is that compression depth matters. We've long believed that to be the case and certainly have some animal data to support it, but this is the first time, to my knowledge, that compression depth has been correlated with outcomes in people. Until recently, the technology to accurately measure compression depth during CPR in clinical care was not possible, but now that it is and we can see the clinical benefits, we need to be finding ways to improve it.
Any further comments to add or post-study developments to note?
Edelson: This study adds to the growing body of literature that CPR quality is important.
Download "Shallow chest compressions and long pre-shock pauses predict defibrillation failure during cardiac arrest,"Resuscitation. 2006; in press