In the medical device world, Usability Engineering (IEC62366 The application of Usability Engineering or its 60601 counterpart IEC60601-1-6) is a required tool within the validation of a medical device. Regardless of if it’s, software, active, or IDV, Usability engineering helps us understand how the device (or system) react within a real-world application.

It draws from the risk principles outlines within ISO14971 and identifies hazardous situations that the user may be presented with while using the device, but there’s so much more than just this…..

Firstly, we see a lot of organisations struggling with the concept of the “hazard related use scenario” and “hazards”, so we’ll try our best to put this is more real terms.

The risk assessment process is much the same as you would typically find within the medical device space, keeping in mind the particular requirements of EN ISO14971 against ISO14971 if you’re delivering in the EEA.

Once making an assessment of where our hazards are, we start the controls process

Take your typical smoke alarm.

A failure of the system might be that the siren is not loud enough. ISO12239 sets out how to technically develop and test a fire system that is compliant so our control will be to design a system to these requirements and verify in accordance to the test procedures.

However; useability engineering seeks to determine if the interface between the device and people functions to eliminate hazardous situations, An interface can present as a click, noise, buzzer, beep, light, feel, text, training, symbol or any other feature that interacts with the user or patient.

So, we take the same fire alarm example that has been designed and tested in accordance to the relevant particular standards and we place the user in a “scenario” where the hazard is present (controlled conditions of course – we don’t want our testers hurt).

In this case our Hazardous scenario is, the user does not understand what the alarm means therefore, does not act upon it. Some controls to prevent the hazardous situation could be to include some training or reference material.

At this point we need to tell you not to look at “unforeseeable abnormal use” or, in other words, malicious intent. There’s no risk control that can ever prevent, or reduce, this. We take into account, normal and foreseeable abnormal use conditions, but you already know that, right?

Given the above, as part of the interface design, we include some training video and then some information within the user manual.

The second hiccup that people get stuck on is verifying the control is effective.

We talk about video’s and user manuals as being a control, most organisations verify this by checking to see if the literature is in place and available. BIG NO NO.

This simply tells us that you have done what you said you were going to do and not if your control is effective is preventing the use scenario from happening.

A better verification method is to give the user the required training and literature to read, then place them in a situation where the alarm is activated. If your controls are successful, then the user should react as expected.

But wait, there’s more!

This is simply not enough; you need a measure of how successful were. How identifiable, understandable, and, evidently “usable” was your device in this hazardous situation? This feedback is critical in the development of your device. Although testers managed to avoid the hazard, most may have found your control difficult to understand. If this is the case. are you still convinced that this is an effective control?

This shows a quick example of how usability, in its simplest form, is applied.

Our medical device consultants have implemented usability studies of all types of medical, and non-medical devices, to help designers better understand how their devices perform in the hands of the user.

Contact us to find out why we are your best choice for usability engineering and medical device consultancy.

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