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| A depiction of how Thoratec's HeartMate II left ventricular assist device is worn by the patient--Courtesy of Thoratec |
Adverse events and recalls aren't always proof of a mechanical error. Some devices are difficult to use. Human error and patient harm can stem from unclear electronic interfaces or complicated procedures for use.
The FDA just released a draft list of devices whose applications for marketing approval should include human factors data to ensure usability is considered during the design and regulatory process. It also finalized a guidance from 2000, providing updated information on the methods by which companies should collect and submit human factors data.
Several of the devices on the list are used for drug-delivery purposes, such as anesthesia machines, auto injectors, dialysis systems, infusion pumps (including implanted ones), hemodialysis systems, insulin pumps and negative pressure wound therapy devices intended for home use.
The growing use of home healthcare poses a challenge to the FDA and makes usability even more crucial. Due to the rise of biologic medications (which typically don't come in oral formulations), patients are increasingly being asked to inject themselves, but a December 2014 study found that only 16% of patients use auto injectors properly, with more than half skipping three or four steps.
The other devices on the list are ablation generators, artificial pancreases, duodenoscopes, external defibrillators, endoscopic ultrasound systems, robotic catheter manipulation systems, robotic surgery and catheter manipulation devices, ventilators and ventricular assist devices.
Usability issues with ventricular assist devices have been particularly severe. Last year, HeartWare's Ventricular Assist Device (or HVAD) was hit by 5 Class I recalls, and in 2014 four of Thoratec's ($THOR) HeartMate II patients died after struggling to switch to backup system controllers when their external battery pack ran low on power.
But usability issues related to the devices aren't too surprising given the inherent challenges of wearing critical components of a blood pump around the waist (such as batteries), walking around with a wire underneath one's shirt that connects to an implanted pump, or being tethered to a power outlet that connects to an electrical socket (when the batteries are not in use).
Indeed, ventricular assist devices demonstrate the extent of the challenges the FDA and industry can face in designing and regulating devices for human factors.
In its final guidance containing recommendations on how to apply human factors and usability to medical devices, the FDA recommended considering device users, environments and interfaces during the design process.
Among the myriad recommendations was the performance of so-called cognitive walk-throughs. During the walk-through, participants (presumably patients or doctors) should be questioned and encouraged to discuss their thought processes, as well as any difficulties or concerns they have about using the device.
The agency also called for human factors validation testing of devices, to be collected through interviews, observation, knowledge testing, and in some cases, usability testing of a device under actual conditions of use.
The final guidance concludes with instructions for documenting and reporting the results of the testing for submission purposes, as well as considerations for determining the optimal sample size, and methods of analyzing the resulting information.
- here's the draft list of devices subject to the guidance (PDF)
- here's the final guidance on applying human factors and usability engineering to medical devices (PDF)
Special Report: Four key medical device recalls of 2015 - Patients struggle to safely use HeartWare's blood pump, leading to repeated recalls - GE recalls all of its MRI machines to prevent human errors