Aug 19, 2022

Human factors specialists working in the medical device industry loathe blaming the user. We agree that to err is human, but we also believe that most use errors involving medical devices (including combination products and in vitro diagnostic or IVD devices) are due to design shortcomings. Shortcomings range from poor labeling to computer screens congested with too much information to pushbuttons that provide little feedback.

Of course, users have a responsibility to operate medical devices with due care. When preparing an injection, they should check the medication vial’s expiration date. When filling an intravenous line, they should prime it with fluid to remove all the air in accordance with the procedure. When entering a child’s birth weight into an electronic health record, they should make sure they are doing so using the right units of measurement (i.e., 8 lbs., 4 oz. versus 3.7 kg).

But remember, to err is human. Developers need to be mindful of the worst-case user and worst-case scenarios and, therefore, design medical devices with a defensive mindset. This is what use-related risk analysis and mitigation are all about.

The risk mitigation greatest hits include such user interface design solutions as these:

  • Use color, texture and shape coding to help ensure users properly connect components.
  • Add format checks, data range checks and confirmations to ensure that users enter data correctly into forms.
  • Design hand tools to accommodate users with hands of varying size and strength.
  • Add simple illustrations to instructions for use to clarify procedures.
  • Alert users to hazards and problems via salient warnings and alerts without causing information overload.

These are a small fraction of the things you can do to make medical devices safer to use. Many more principles for safe design can be found in textbooks and guidance documents.

However, the key to successful use-related risk mitigation is having the right mindset, which is:

Don’t Blame the User

It is easy to observe a use error and conclude that the person using the given medical device made the error because of one or more of these conditions: careless, forgetful, unqualified, rushing, non-compliant, unintelligent, fatigued, distracted and more. However, human factors specialists view these conditions in much the same way a mechanical engineer would view ambient temperature regarding an engine’s performance. They would have to account for running an engine on the most frigid and hottest days of the year. Similarly, human factors specialists--working collaboratively with other specialists--should be focused on designing a medical device that stands up to use by people who might not always be at their best. Sometimes, this means reminding people to perform an operational step and not letting things progress until they do so; a simple solution to the common human vulnerability to forgetfulness.

In summary, don’t blame the user for use errors. Instead, eliminate opportunities for use errors, warn users to be cautious and put safeguards in place. In parallel, we’ll count on users to do their very best to operate medical devices with due care, noting that people are not perfect.

Additional human factors engineering and usability resources from Emergo by UL:

  • Human factors analysis for medical devices, IVDs and combination products
  • Human factors design and prototype development support
  • Medical device, IVD and combination product evaluation


  • Michael Wiklund