Pinch Hitting with a Defibrillator
The Importance of How AED Manufacturers Test Usability with Human Factors Testing
As you board an airplane, instantly the flight attendant rushes over, shouting, “Hey, it’s an emergency! The pilot didn’t show up today so we need you to fly the plane!” He grabs you and drags you into the cockpit, where a baffling array of instruments, knobs, and displays abound, as the co-pilot sits awaiting your instructions. What do you do?
Having to pinch hit in this high-stakes flying situation is a pretty unlikely scenario! But what about saving a life with an automatic external defibrillator?
We don’t expect people to have to perform like pros in most situations, but expectations are different when it comes to saving a life using an AED. And that’s where human factors design comes into play. By virtue of its design, an AED has to be easy to use by an untrained person during a time of crisis when panic is high and the user might not be thinking clearly. Everything from the pace of voice prompts, visual alerts, the color and shape of buttons, the illustrations on the box and on the pads, even the size of fonts or loudness of tones can have an effect on how well an AED functions in the hands of a novice user.
In my 6 years as the Branch Chief for the Pacing, Defibrillators and Leads Branch at FDA’s Center for Devices and Radiological Health, I found the science of “human factors engineering” to be one of the most interesting parts of my job. It was always fascinating to see how well AED manufacturers worked to improve the usability of their devices. My team would review company’s “human factors evaluation” studies, a required part of the clinical evaluation of every AED. In these tests, companies would bring in naïve subjects to interact with their AED during a simulated emergency, while videotaping and scoring their success at each step, documenting the kinds of mistakes they made.
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At the FDA, my team also learned what happens when human factors was not optimal. Even when devices were well designed for usability, we’d see reports of real-life users struggling to use an AED successfully, suggesting that there could always be some room for improvement. For example, users sometimes pressed the power button off, rather than the shock delivery button. In a panic, they’d forget to take the adhesive backing off the pads prior to placing them on the chest. Or they’d forget to take the person’s shirt off, placing pads on top of clothing instead. We heard of one case where the AED couldn’t be opened on an airplane in flight because the change in pressure caused the case to seal excessively tight. Making sure the AED can work in its use environment – including on airplanes – is part of the human factors design goal.
Few technologies require the level of human factors design that an AED does. But knowing that AEDs are designed to be intuitive to use as a requirement for FDA approval should give most people comfort that – if the emergency arises – they’ll be able to use one successfully the very first time.
About the Author: Megan is Revive Solutions’s FDA Strategist, and advises the company on its regulatory strategy and participates in all FDA interactions. Most notably, Megan was the former FDA Branch Chief of Cardiac EP Devices, where she led the Cardiac Electrophysiology and Monitoring Network. Specifically, she was responsible for ensuring coordinated regulation of pacemakers, defibrillators, EP devices, and cardiac monitoring systems at FDA.