Automated external defibrillation by first-responders

This review examines whether the use of automated external defibrillators by first-responders improves the survival of adults who suffer cardiopulmonary arrest. We also examined the risks associated with these devices, based on a review of the literature using the standard Prescrire methodology. Automated external defibrillators detect ventricular fibrillation with almost perfect sensitivity and specificity. Several studies showed that the use of automated external defibrillators by trained first-responders is associated with increased survival among patients who suffer out-of-hospital cardiac arrest in public places. A retrospective study suggests that installing automated external defibrillators in public places would only allow about one-fifth of all victims of cardiac arrest to be treated; this would increase the average survival rate after cardiac arrest from about 5% to 6.5%. The main risks associated with these devices are burns to the patient's skin at the electrode contact points, and inappropriate shock to the user--a rare occurrence. Interactions between automated external defibrillators and implantable defibrillators have been described. Drug delivery patches on the patient's chest can prevent electrode-skin contact and may block delivery of the electric discharge. In the United States, about 1 in 5 functioned over a 10-year period, mainly due to electrical or software problems. In summary, automated external defibrillators have a favourable risk-benefit balance, at least in trained hands. Specific training helps first-responders to act purposefully and without delay, and to implement the chain of survival until medical help arrives.