The study's authors point out "numerous confirmed AED malfunctions occurred during the past decade." However, they also note "the total number of device malfunctions is small compared with the number of lives saved."

"Indeed, hundreds of thousands of patients underwent attempted resuscitation of ventricular arrhythmias by an AED during the study period, accounting for thousands of lives saved," conclude the study's senior author, William Maisel, M.D., MPH, director of the Pacemaker and Defibrillator Service at Beth Israel Deaconess Medical Center in Boston, and co-author Jignesh Shah, M.D., of the Beth Israel Deaconess Medical Center's Cardiovascular Division.

That point is one John Hinson, president of Bothell, Wash.-based Cardiac Science Corp., emphasized in an interview with Occupationalhazards.com.

"I'm hoping the benefits of deploying AEDs to save lives will not get lost in some of the buzz surrounding the study itself," Hinson said.

Advisory Rate Did Not Significantly Increase

Maisel and Shah examined Weekly Enforcement Reports issued by the Food and Drug Administration (FDA) from January 1996 through December 2005 and tallied the recalls and safety alerts (collectively referred to as advisories) affecting AEDs and AED accessories.

According to Maisel and Shah, there were 52 advisories – which affected 385,922 AEDs and AED accessories – during the study period. Every major AED manufacturer recalled products during the study period, the authors note.

Still, while the annual number of AED advisories and AEDs affected by those advisories went up between 1996 and 2005, Maisel and Shah point out "despite increasing AED complexity, the AED advisory rate did not significantly increase during the study period."

A total of 164,102 AEDs – 21.2 percent of AEDs – were affected by advisories during the study period. According to the study's authors, the most frequent reason for an AED advisory was "electrical" (eight advisories), followed by "software" (six) and "failure to shock" (five).

More Advisories May Be Due to Improved Self-Diagnostics

FDA, in a statement released Aug. 10, said most of the conclusions reached in the study "are consistent with FDA's own findings." However, the agency believes the increase in AED advisories may be attributed to improvements in the devices' ability to self-diagnose hardware and software problems.

"This capability may result in users reporting problems before a device is ever used on a patient," according to FDA.

The agency also noted while 21.2 percent of AEDs were affected by an advisory, that does not necessarily mean every affected device malfunctioned.

Indeed, Maisel and Shah point out advisories "are a surrogate marker of device reliability."

"Importantly, some advisories are issued even when the risk of device failure is less than 1 percent," Maisel and Shah wrote.

FDA recommends AED users continue to report device malfunctions to the manufacturer and the agency. FDA also advises AED users to "heed device error messages and warnings during regular device self-checks and respond appropriately to recall notices and safety alerts."

Study Highlights Need for AED Systems

Speaking on behalf of the American Heart Association, Lance Becker, M.D., a professor of emergency medicine at the University of Pennsylvania, said Maisel and Shah conducted "an important study" that highlights the need for employers who purchase AEDs to implement AED management systems governing AED training, maintenance and proper usage.

"Quite honestly, I think the largest threat to the unit not working is failure to properly place it – sticking it in a locked cabinet, not having it accessible when you need it – and not performing maintenance on it," Becker told Occupationalhazards.com.

According to Becker, the four critical components of an employer's AED system should be:

• Training on the proper use of AEDs and in CPR;
• Practice on using the device in mock emergency situations;
• Making sure a plan is in place to quickly notify EMS in the event of an emergency; and
• Continuous quality improvement, which includes a plan for regular, onsite maintenance and ready-for-use-checks.

Becker also urged AED users to register the device with the manufacturer and comply with all the manufacturer's guidelines.

Cardiac Science's Hinson agreed that training users on how to properly deploy and maintain AEDs plays an important role in keeping the devices functioning properly.

"If you simply are following the manufacturer's guidelines or are well-trained in their use, they're pretty reliable devices in that kind of context," Hinson said. "Since we're talking about laypeople performing what previously was a medical procedure, you want to make sure the risk of error is reduced to the lowest amount possible. The best way to do that is to make sure the device is operational."

Study Authors Worry About Tracking of AEDs

Maisel and Shah fret that it is nearly impossible to track who the end user of an AED will be during an emergency, making it "impossible to know how many AED units were actually fixed or taken out of service during the study period because of those advisories."

They note implantable cardioverter-defibrillators (ICDs) "are routinely 'registered' with the manufacturer" when they are implanted into a patient, but "no such process reliably occurs with AEDs."

Therefore, Maisel and Shah conclude, FDA and the AED industry need "to develop a reliable system that will permit timely, accurate communication to potential users and identification of affected advisory devices."

FDA objects to the authors' assertion, pointing out FDA regulations require manufacturers to track AEDs, while manufacturers have "processes in place to identify the location of a device in the event of a recall."

"Our records show that these devices are being tracked with a high level of accuracy," FDA said in a statement. "In fact, more than 95 percent of the AEDs affected by Class 1 recalls in 2005 were returned to the manufacturers or taken out of service. Fewer than 3 percent were lost or stolen."

- Josh Cable, occupationalhazards.com