AEDs Efficient and Effective

Automated external defibrillators appear efficient and effective for responding to cardiac arrest

March 6, 2001

Literature supports expanded role of AEDs in emergency care

The automated external defibrillator (AED) represents an efficient method for delivering defibrillation to people who suffer cardiac arrest outside a hospital, and studies on its use by both traditional and non-traditional first responders suggest that it is safe and effective, according to an article in the March 7 issue of The Journal of the American Medical Association (JAMA).

John P. Marenco, M.D., and colleagues from the New England Cardiac Arrhythmia Center, New England Medical Center, Boston, examined advancements in AED technology, reviewed the impact of AEDs on time to defibrillation and survival, and explored the future role of AEDs in the effort to improve survival following sudden cardiac arrest. The authors searched MEDLINE for relevant articles published from 1966 through December 2000, and selected 101 articles for critical review. Reference lists of relevant articles, news releases, and product information from manufacturers were also reviewed.

According to background information cited in the article, cardiovascular disease is the major cause of death in the United States, resulting in nearly 1 million deaths a year. Between 250,000 and 500,000 of these deaths are sudden and unexpected. Most sudden deaths from cardiac arrest occur outside the hospital, and only 1 to 5 percent of these patients are estimated to survive to hospital discharge. Most people experiencing cardiac arrest have no history of severe heart disease, and sudden cardiac death is frequently the first manifestation of cardiovascular disease. Early defibrillation has been shown to be critical to improving survival.

According to the authors, the use of AEDs has become an important component of emergency medical systems. The AED is a lightweight portable device containing a battery, capacitors, and circuitry designed to analyze cardiac rhythm and inform the operator whether a shock is indicated. Information is transmitted to the device by electrode pads used for both monitoring and shock therapy. Once activated, AEDs have voice and text prompts to guide the user through a few simple steps.

Based on their evaluation of the available studies, the authors write that "recent advances in AED technology and design have resulted in marked simplification of AED operation, improvements in accuracy and effectiveness, and reductions in cost."

"Use of AEDs by first responders and laypersons has reduced time to defibrillation and improved survival from sudden cardiac arrest in several communities," the authors report. And they continue: "Initial studies of the cost-effectiveness of AED use in comparison with other commonly used treatments are favorable."

The authors report initiatives at the state and federal level are paving the way for more widespread access to defibrillation, as legal barriers to public access defibrillation (PAD), both perceived and real, are slowly eliminated. "The success of manufacturers in developing more advanced AEDs has reduced concerns over inappropriate shocks and potential harm of defibrillation by laypersons," they write.

"These improvements have buoyed the efforts to pass Good Samaritan laws, and currently 45 states have passed legislation protecting laypersons who use an AED in good faith," they continue. "On May 20, 2000, the president proposed an initiative directing the creation of criteria for the placement of AEDs in federal buildings and on all commercial airlines in an effort to save up to 20,000 lives each year."

The American Heart Association (AHA) promotes the placement of AEDs in such areas as airports, convention centers, sports arenas, casinos, shopping malls, and large office buildings. The AHA supports the concept of PAD. "This concept promotes the expansion of the role of defibrillation to both minimally trained first responders (police officers, firefighters, security guards, flight attendants) and to trained laypersons who witness an arrest," the authors write.

"Additional studies are needed to determine how widespread the deployment of these lifesaving devices should be, provide more data on the cost-effectiveness of PAD, and further define the role of the AED in children and infants," they recommend.

(JAMA. 2001; 285:1193-1200)

Editor's Note: Study co-author N.A. Mark Estes III, M.D., has received an honorarium from Medtronic for a talk.