AAMI News January 2018

Preventing Device Misuse Starts with Understanding Users, Experts Say

Misused Devices
Medical devices pass through the hands of people with different skills, priorities, cultures, and expertise, often resulting in misuse, abuse, and ultimately broken equipment.

Not all medical devices live happy lives. Too often, they are misused, abused, and ultimately broken. Although training, cleaning practices, and organizational culture can help mitigate this risk, medical device manufacturers hold the keys to preventing the issue from ever occurring—designing a device that is either less likely to break and/or uses human factors principles to reduce the likelihood of misuse.

“The best way to ensure a device can’t be misused is to design it in a way that prevents misuse,” said Mark DeSilets, vice president of research and development at Mizuho OSI.

Specific human factors considerations that manufacturers may take into account include the force required to initiate a device action. Providing reasonable control forces and feedback to users when a device is actively processing commands can help prevent pounding on buttons when a quick response is not observed.

“Any product that triggers frustration may likely be abused, so attention to design for usability is important,” said Pete Doyle, a human factors engineer at The Johns Hopkins Hospital in Baltimore, MD.

Other considerations include how securely multiple devices and their accessories are mounted, keeping the center of gravity in mind to prevent, for example, an anesthesia machine from tipping when it is wheeled over an elevator gap.

“From a human factors standpoint, it seems pretty clear. From a manufacturing standpoint, it can be hard for us to implement these human factors principles. But we’re getting better at that,” said Pachu Cuesta, clinical manager for medication management solutions at Becton Dickinson and Company in Vista, CA.

Building Solutions into Devices

Trying to get the human factors design just right for a new medical device requires a substantial investment of time and money. At Mizuho OSI, the process begins with simulated use testing and in-house validation, where clinicians come in to try out the new product. That’s followed by a limited release of the device to a select few customers who can let the designers and engineers know what issues, discomforts, or annoyances slipped through the cracks before the full market release. Three-dimensional printing and modeling also assist in the application of good human factors principles.Even with all that effort, many manufacturers will admit that they sometimes get design elements wrong.

“I’d love to tell you we always get it right the first time, but that’d be a lie,” DeSilets said. “Users find ways to handle equipment in ways that were unforeseen by the development team and undiscovered during the clinical evaluation process. Therefore, we are left to remedy discovered misuse through product updates subsequent to release.”

DeSilets gave the example of healthcare workers who pulled out critical pins that supported the carbon fiber spinal frame from a surgical table. These “T-pins,” explained DeSilets, secure a frame to which supports for the head, arms, chest, hip, and leg are attached. Removing the pins opened the possibility of an anesthetized patient falling to the floor.

“They were confused because there were two sets of pins. It’s difficult to imagine how people could be confused about which pins support which part of the device, and even so, that they could remove the pins accidentally under load,” DeSilets said. “I’m a bodybuilder, and I’ve tried to pull those pins out under load—it’s really hard. I can’t imagine how they managed to do that by accident.”

The immediate response from Mizuho OSI was to retrain users so they would not pull out the wrong set of pins. The permanent solution was redesigning the next generation of tables to lock automatically. “That’s the mindset we have to keep … to make it impossible for all but the most malicious of users to do any harm,” DeSilets said.

This article was excerpted from the cover story of the November/December 2017 issue of BI&T, www.aami.org/bit.