Using automated external defibrillators in hospitals on patients with sudden cardiac arrest is ineffective and potentially harmful when compared with traditional defibrillators, according to study in the Journal of the American Medical Association.
The study, led by cardiologist Paul Chan, MD, at Kansas City-based Saint Luke's Mid America Heart and Vascular Institute, examined data from the National Registry of Cardiopulmonary Resuscitation of 11,695 hospitalized patients with cardiac arrest between Jan. 1, 2000, and Aug. 26, 2008, at 204 hospitals following the introduction of AEDs on general hospital wards.
AEDs diagnose sudden cardiac arrest, judge whether defibrillation is needed, and deliver an electrical shock to restore the heart's normal rhythm. For cardiac arrest patients who respond to a defibrillation shock (19% of the study's population) there was no difference in rates of survival between those treated by an AED or a conventional defibrillator.
"It was a disappointing finding," Chan says.
In some circumstances, use of AEDs in the hospital was associated with higher death rates.
"For the majority (81%) of the cardiac arrests which do not respond to defibrillation, the use of AEDs to assess the initial rhythm in patients with cardiac arrest was associated with lower survival than with a conventional defibrillator," Chan says.
While AEDs have improved survival in out-of-hospital settings such as schools, airports, and sporting events, data on their effectiveness in hospitals—where they're increasingly used—is limited.
The findings seem surprising, Chan says, but they make sense. "Because these cardiac arrest rhythms are not treatable by defibrillation, assessment with an AED should not result in any benefit. But given that an AED takes a much longer time to assess a rhythm than a medical provider with a conventional defibrillator, their use likely deprives a cardiac arrest patient with a non-shockable rhythm of critical CPR time during the initial minutes, when perfusion to their organs (brain, liver, kidneys) is paramount. That delay may be hurting the patient, and explains why AEDs may have been associated with lower in-hospital survival."
Chan adds that the use of AEDs in public settings, however, remains essential.
"Although our study found that an AED does not appear to be useful in the hospital setting, that does not mean that an AED is not useful outside the hospital, especially in public places," Chan said. "Because hospitals are equipped with staff that can perform CPR effectively, shock patients when needed, and give important cardiac arrest medications, the benefits of AEDs in a hospital may be harder to realize than outside the hospital."
The research concludes that hospitals relying on AEDs should reconsider treatment approaches.
"Our institutional CPR committee has struggled with what to tell the first person who responds to the bedside of a patient in cardiac arrest," says Steven Kronick, MD, assistant clinical professor of emergency medicine and director of advanced cardiac life support at the University of Michigan Health System, whose investigators helped research the study.
"This study supports that continuous chest compressions should be provided immediately and without interruption until the cardiac arrest rhythm can be determined. It also shows that in the hospital setting, rhythm identification should be done by the medical provider rather than by the AED, where delays in rhythm analysis can be significant," Kronick said.
More than 50,000 AEDs have been purchased by hospitals alone since 2005.
"Time to defibrillation is an important quality metric, but there has been no silver bullet to achieve shorter times to treatment to date," Chan says. "AEDs have been touted as a logical solution, and hospitals are buying these in increasing quantities. But, they do not appear to improve survival. In order to improve the quality of in-hospital resuscitation, we need to go back to the drawing board and do the hard work to identify innovative strategies to improve survival for cardiac arrest patients."
John Commins is the news editor for HealthLeaders.