Study: One-fifth of AED failures traced to battery, power problems

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An analysis of reports of automated external defibrillator (AED) failures in which a patient died found that nearly half of the failures occurred during an attempt to charge and deliver a shock, and more than a fifth involved battery and power problems. But authors of the report, published Aug. 29 in the Annals of Emergency Medicine, cautioned that the federal database’s limitations made calculating failure incidence rates problematic.

“Survival from cardiac arrest depends on the reliable operation of AEDs,” lead author Lawrence A. DeLuca, MD, of the Arizona Emergency Research Center at the University of Arizona’s Department of Medicine in Tucson, Ariz., said in a statement. “AEDs can truly be lifesavers but only if they are in good working order and people are willing to use them.”

DeLuca and colleagues set out to first determine the number and types of AED failures in which a death occurred and then to place the failure within the AED’s power on-analyze-shock sequence. They also wanted to examine the frequency of unexpected shutdowns and use of backup devices.

They performed a retrospective analysis of AED adverse event reports filed in the FDA’s Manufacturer and User Device Experience (MAUDE) database between January 1993 and October 2008. By law, any AED failure that involves a fatality is required to be reported in MAUDE. The researchers developed and applied an internally validated data abstraction tool that included descriptive and analytic questions and a multiple step review process.

DeLuca et al identified 1,150 failures within the total 40,787 reports filed during the study period that were fatality events. Of the 1,150 cases, 45 percent of AED failures occurred during an attempt to charge and deliver a shock. AEDs powered on but failed to give a complete rhythm analysis in 22 percent of the cases. Backup devices delivered charges to patients in 13 percent of the cases.

While only 4.7 percent of malfunctioning AEDs gave a battery-low indication, 9.6 percent powered off unexpectedly. The analysis showed that battery and power problems were the cause of failures in 23.2 percent of cases, while pads and connectors were cited for 23.7 percent of failures.

“Regardless of the cause, these errors went unrecognized during the automated external defibrillator self-test sequence,” they wrote.

MAUDE presented many limitations. Data were incomplete and raw, it was unclear if reports were filed by witnesses or other parties and information could not be corroborated, they claimed.

“It is tempting to calculate a failure rate based on the number of reports and manufacturer reports of units sold,” they wrote. “However, failures are underreported for many types of devices.”

The authors recommended earlier and better detection of problems within the charging and discharging sequence and called for backup units in public AED access sites, if feasible, with sufficient reporting to determine their cost-effectiveness.