Prompt response to cardiac arrest is critical; seconds lost reduce the chances for patient recovery. While other rescue procedures like CPR do help and buy rescuers time, when a shock is needed, it’s imperative for the equipment to work well and, in some cases, provide rescuers with feedback.
Automated external defibrillation (AED) saves lives when applied correctly, and as not every responder is a medical professional, efforts to improve AED safety, utility and responsiveness have lead manufacturers to develop real-time feedback to responders. These can include directions and assistance regarding depth and timing of CPR compressions and information on patient condition.
The devices themselves read the victim’s heart rhythm and some models use this information to work independently of rescuer efforts. The directions for use being simply to apply the pads correctly, press a button and step back. Fully automated models are intended to better provide assistance when the first responder to the arrest isn’t a medical professional.
However, things can and do go wrong with AEDs. And, when they do, appropriate responses to those errors are important to avoid history repeating with another patient.
Recently, the U.S. Food and Drug Administration (FDA) strengthened regulations surrounding preapproval of AEDs and their components. These regulations would make premarket approval (PMA) for AEDs and accessories mandatory. Once in effect, manufacturers are required to provide assurance of quality and safety of devices by providing quality systems information and to allow the FDA to inspect manufacturing facilities. “Reviewing PMAs will allow the FDA to more closely monitor manufacturers’ Quality System design practices and manufacturing changes that have contributed to recalls and adverse events associated with AEDs,” says William H. Maisel, MD, MPH, of the FDA. Maisel is the chief scientist and deputy center director for science at FDA's Center for Devices and Radiological Health based in Washington, D.C.
Maisel notes that the requirement to submit the new PMAs does extend to currently marketed—and previously approved—devices. "Each manufacturer of a currently marketed AED device was required to submit a notice of intent to file a PMA within 90 days of the effective date of FDA’s order for any device that it intends to continue to distribute. After submitting an intent to file, the manufacturer must submit its PMA within 18 months of the effective date of the FDA’s order,” he says.
Maisel stresses that by and large, AEDs are safe. These new regulations, like the recalls prompted by reported device failures are intended to make available devices even safer, “FDA believes that consumers should have confidence in using AEDs that are in public places. Through the manufacturers’ quality systems and the FDA’s recall process, most problems with AEDs are found before the device is ever used,” he says. This should, in turn, reduce the number of reported device failures.
Between 2005 and 2011, around 72,000 AED device failures were reported to the FDA’s MAUDE (Manufacturer and User Facility Device Experience) database, leading to 111 manufacturer recalls of devices (www.FDA.gov, 2015). As part of the new regulations, Maisel says that “Class III devices (including AEDs) that were put into commercial distribution after September 24, 2014, are subject to Unique Device Identification (UDI) requirements. One of the primary anticipated benefits of the UDI System is that it will allow more accurate reporting, reviewing and analyzing of adverse event reports so that devices that have performance concerns can be identified and corrected more quickly. In addition, it is intended to enhance analysis of devices on the market by providing a standard and clear way to document device use in electronic health records, clinical information systems, and registries.”
This should improve reports to MAUDE and similar databases maintained by the manufacturer. Reporting to the FDA is mandatory when the patient dies, particularly if the device is considered to be at fault. Communication of reporting requirements to groups and individuals using or maintaining AEDs is important, as not everyone who uses or maintains AEDs is clear to whom they should report failures. But, reporting is key to improving problems with devices as quickly as possible.
According to Maisel, AEDs are subject to “tracking regulation (21 CFR part 821), which requires manufacturers to establish tracking systems that will enable them to promptly locate devices in commercial distribution.” Tracking information may be used to facilitate notifications and recalls ordered by FDA in the case of serious risks to health presented by the devices.
Still, no unified database of all AED device failures across all manufacturers exists, making the study of trends difficult. While a good resource, MAUDE wasn’t designed specifically for AEDs. The database is intended to encompass medical device reports to the FDA from manufacturers and device user facilities as well as voluntary reporters, such as clinicians and consumers (www.accessdata.fda.gov). The hope is to monitor for safety all devices approved by the FDA and provide a warning system if something goes wrong. However, the MAUDE database covers a broad spectrum of devices, not just AEDs, so teasing apart that data alone can be difficult.
The FDA notes on the MAUDE website that the information they provide shouldn’t be the sole source for researching device failure trends and may not show the full picture.
A device failure opens a line of inquiry
It was an AED failure that led Lawrence A. DeLuca, EdD, MD, to exploring the question of frequency and type of device failures. DeLuca, who works for the University of Arizona in Tucson, had first-hand experience in trying to report faulty AEDs to the FDA and to a manufacturer. He was one of the responders treating an arrest in a camp in Pennsylvania. “All of the things we teach people to do as lay rescuers happened properly. Someone noticed right away there was a problem. This was a witnessed arrest. Someone saw this person collapse. Two people who were good, solid CPR, medical people got down there on the floor immediately that should have bought us time,” he says.
However, even though they got the AED to the patient around three minutes in, when the time came to deliver the shock, the device went dead. The device was brand new, installed per the directions that morning and the batteries should have been within their usage parameters. Unfortunately, by the time a second AED arrived, the patient had been in arrest for nine minutes. And by the time the paramedics arrived on the dark night in the middle of nowhere, the patient had been in arrest for 30 minutes.
Most people’s ability to survive cardiac arrest declines about 7 to 10 percent a minute that they are in abnormal heart rhythm, DeLuca notes. “The CPR buys you some time but it doesn’t usually take you out of the abnormal rhythm. So what happened was we kind of crossed over from the point where the first AED arrived on the greater than 50 percent likelihood of getting this person out of this rhythm alive, to the point where the likelihood of getting this person back alive was much less.“
DeLuca deemed the problem a battery fault. He decided to report it to both the manufacturer and the FDA, but didn’t know about the reporting requirement at the time. When he spoke to the manufacturer, it became clear that part of the problem was the way the system checked to make sure Lithium-ion batteries were functional and would carry enough charge to shock a heart into rhythm. Along with sending the device back to the manufacturer, his feedback helped instigate a change to how the AEDs perform self-tests.
The incident drove DeLucas curiosity to explore AED failures reported to the MAUDE system in which patients died. He and his team found that 45 percent of reported failures between 1993 and 2008 occurred during attempts to charge and deliver a shock. Some 22 percent of failures involved AEDs that powered on but did not completely give rhythm analysis. The most frequently identified cause of failure was pads and connectors in 23.7 percent of total cases. And, as for the device failure that put DeLuca on the line of inquiry, 23.2 percent were related to battery or power malfunctions (Ann Emerg Med. 2012; 59:103-111).
However, DeLuca notes that the self-reported nature of the data in MAUDE made it difficult to obtain even this level of understanding of fatal device failures. Current technology could help make reporting much easier. To that end, he envisions using internet connectivity to allow devices to report in after every firing, both to the manufacturer and to a common database.
Recording failures, gaining better feedback
In Belgium, there is no central reporting for AED failures. This was part of the problem faced by Paul Calle, MD, PhD, of the University of Ghent when he looked into treatment decisions made by responders in his region. Calle is an emergency physician in the University’s Maria Middelares General Hospital and serves as the region’s hub for reviewing and training emergency medical services on the use of AEDs.
Calle has created his own database of incidents where AEDs were used for his region. “This is only a very local activity because there is no funding and no reporting obligation here in Belgium and in most countries in Europe to do larger surveillance,” he says. His database of more than 3,000 cases has meant that he can review positive and negative influences in rescues happening with AEDs in his area, find areas where more training is necessary and, in the case of research published in Resuscitation, when there is an issue with the algorithms being used by the AEDs.
Among the issues he has seen with the devices used in his region, algorithms in some devices misinterpreted 16 percent of shockable rhythms and 4 percent of non-shockable rhythms leading to inappropriate shocking decisions (Resuscitation. 2015; 88:68-74). In response, he recommends higher sensitivity and specificity for algorithms and filters that keep caregiver’s actions from inadvertently creating artifacts that may be misinterpreted by the device. “If something is not the way it should be with the defibrillator’s decision to shock or not to shock, about 50 percent of the time it’s related to the caregiver and 50 percent the device,” he says. “These two things should be improved and when you look at the elements that can be provided by the manufacturer, filters and a better algorithm could make the difference between interpreting shockable and not shockable rhythms.”
Calle says he believes a large part of ensuring future successes is feedback: Feedback to the manufacturers and to responders through post-action reporting. Training to cover situations caregivers may experience provides both with a better understanding of how to avoid future problems before they happen. More oversite may be needed globally to insure patients and providers have the best equipment and trained professionals possible at times of crisis.
Back in the U.S., Maisel concurs. “This level of oversight is appropriate for the level of risk these devices present and the importance of their reliability in life-threatening emergencies.”