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15-04-2010 | Cardiology | Article

Modified AED protocol reduces CPR pauses but fails to improve survival


Free abstract

MedWire News: A revised automatic external defibrillator (AED) protocol effectively reduced pauses in cardiopulmonary resuscitation (CPR) and improved overall hands-on time, shows a US study.

However, this failed to translate into improved survival to hospital admission in patients with ventricular fibrillation (VF) out-of-hospital cardiac arrest.

Researchers analyzed 845 out-of-hospital cardiac arrest patients with VF treated with an AED by firefighters trained in basic life support. Patients were randomly assigned to a control protocol, based on the Guidelines 2000 resuscitation protocol, or the modified study protocol, based on 2005 international CPR guidelines updates.

The control protocol involves sequences of up to three stacked countershocks, with rhythm analyses initially and after the first and second shocks; the study protocol featured 1 minute of CPR before the first shock, shorter PCR interruption before and after each shock, and no stacked shocks.

As reported in the journal Circulation, study protocol patients (n=421) had shorter preshock pauses (9 vs 19 seconds, p<0.001) and postshock pauses (11 vs 33 seconds, p<0.001) than control protocol patients (n=424). They also had a greater overall CPR hands-on ratio (61% vs 48%, p<0.001) and fewer shocks (2.5 vs 2.9, p<0.001).

However, similar proportions of patients in each group survived to hospital discharge (13.3% vs 10.6%, p=nonsignificant), achieved return of spontaneous circulation before physician arrival (47.0% vs 48.6%), and survived to 1 year after adjustment for covariates including age, place where cardiac arrest occurred, response time, and more than three AED shocks (hazard ratio=1.03).

“The lack of benefit from increased CPR in this trial, combined with experience from this and other emergency medical systems, suggest that the survival rate may be further improved by efforts focused on other changes to community resuscitation such as increasing bystander CPR, shortning response teims, ro even providing more extensive and regular CPR training to rescuers,” conclude Daniel Jost (Brigade de Sapeurs-Pompiers Paris, France) and co-authors.

In an accompanying editorial, Myron Weisfeldt (Johns Hopkins University, Baltimore, Maryland, USA) and colleagues pointed out that there was a nonsignificant trend towards improvement in the “arguably more important clinical outcome” of survival to hospital discharge in patients who were treated by the new study protocol, at 13.3% versus 10.6% of the control protocol patients.

“This suggests the possibility of a nearly 25% increase in survival to this point in time, which, if realized, would provide strong evidence to continue the change in practice,” they reasoned.

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Caroline Price

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