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."