AEDs Do Not Improve Survival from In-Hospital Arrest
During the year after one hospital switched from standard to automated external defibrillators, overall survival from in-hospital cardiac arrest dropped from 23% during the previous year to 18%.
Use of automated external defibrillators (AEDs) in the out-of-hospital setting saves lives, and a recent study suggested a survival benefit from use of AEDs in hospitals. Investigators compared time to first shock and survival rates from cardiac arrest at a large teaching hospital in Michigan during the year before and after standard monophasic external defibrillators were replaced with biphasic AEDs.
No differences in predominant rhythm or medical comorbidities were noted between the 277 patients in the standard-defibrillator group and the 284 patients in the AED group. After the switch to AEDs, rates of survival to discharge did not change significantly in patients with ventricular fibrillation or tachycardia (29% before and 31% after) but declined significantly in patients with initial asystole or pulseless electrical activity (from 23% to 15%). Time to first shock did not differ between the two periods.
AEDs save lives when deployed appropriately in the outpatient setting. This study is not the first to dampen enthusiasm for AED use in other settings: One study showed that AED use in the home did not improve survival in patients with prior anterior myocardial infarction who were not candidates for implantable defibrillators (JW Emerg Med Apr 11 2008). Pausing cardiopulmonary resuscitation (CPR) to apply AED pads might not be beneficial in the hospital, where arrests are less often caused by "shockable" rhythms (ventricular fibrillation and pulseless ventricular tachycardia) than they are outside the hospital. Alternatively, performance of standard defibrillators might be so good that AEDs do not save additional time. For now, the emphasis in the hospital should be on an organized, rapid response with early CPR and defibrillation, either by AED or standard defibrillator.
Daniel J. Pallin, MD, MPH
Published in Journal Watch Emergency Medicine April 3, 2009
Forcina MS et al. Cardiac arrest survival after implementation of automated external defibrillator technology in the in-hospital setting. Crit Care Med 2009 Apr; 37:1229.