Study Shows Use of Automated External Defibrillators on Hospitalized Patients is Not Associated with Improved Survival
The use of automated external defibrillators (AEDs) has been proposed as a strategy to reduce times to defibrillation and improve survival from cardiac arrests that occur in the hospital setting. However, current evidence to support the use of AEDs in hospitals has been mixed and limited to single-center studies. Further, the use of AEDs requires the manual application of defibrillator pads and automated rhythm analysis to determine whether a cardiac arrest rhythm is “shockable” or not. Both steps may lead to interruptions in continuous chest compressions that are delivered during the critical first minutes of acute resuscitation and may adversely affect survival. Therefore, before endorsing their widespread dissemination in hospitals, it becomes critical to demonstrate that AED use improves survival. This study evaluated the association of AED use and survival for patients with cardiac arrests in general hospital wards. Using data from the National Registry of Cardiopulmonary Resuscitation (NRCPR), investigators identified hospitalized patients who experienced cardiac arrests between 1/00 and 8/08 at 204 hospitals, comparing outcomes for patients in whom AEDs were used (n=4,515) to those in whom AEDs were not used (n=7,180).
- The use of AEDs to assess and treat hospitalized patients with cardiac arrest was not associated with improved survival. Overall, the use of an AED in this study population was associated with a lower rate of survival after in-hospital cardiac arrest compared with no AED use (16% vs. 19%).
- Among cardiac arrests due to non-shockable heart rhythms (e.g., asystole, pulseless electrical activity), AED use was associated with lower survival (10% vs. 15%). In contrast, for cardiac arrests due to shockable heart rhythms (e.g., ventricular fibrillation, pulseless ventricular tachycardia), AED use was not associated with survival (38% vs. 40%).
- There were no differences by age or gender, but there was a slightly higher rate of AED use among African Americans.
- This study used an observational design, so the possibility of confounding remains.
- The NRCPR did not collect data on the time of arrival of an AED to a patient, the time required for automated rhythm analysis, or the extent of interruptions of chest compressions; these data also did not have information as to why an AED was or was not used for a given cardiac arrest.
Dr. Nallamothu is part of HSR&D’s Center for Clinical Management Research in Ann Arbor, MI.
Chan P, Krumholz H, Spertus J, Jones P, Cram P, Berg R, Peberdy M, Nadkarni V, Mancini M, and Nallamothu B. Automated External Defibrillators and Survival after In-Hospital Cardiac Arrest. JAMA November 17, 2010;304(19):2129-36.