Usability a key factor in modern medical electrical equipment

The 3rd edition of the international basic standard IEC 60601-1 is being applied across the world. It requires manufacturers to avert the risks of poor usability in equipment. The most efficient way to address usability in an organized manner is to apply the methods of standard IEC 62366.

Improving usability: a must for safety, good for users

We all have cursed badly designed user interfaces; they may come in the form of doors that open in the wrong direction, set top boxes that are impossible to program or water taps that splash water on your clothes. When bad design ends up in hospitals, it may be fatal.

In 1999 The Institute of Medicine issued a report entitled ‘To Err is Human: Building a Safer Health System.’ The report estimated that over 44,000 people die in US hospitals each year as a result of preventable medical errors. Most medical mistakes are not due to individual carelessness, but rather to faulty processes, conditions, and systems that cause people to make errors or fail to avoid making them.

Since 1999 we have learned something. The European Medical Device Directive and United States FDA both demand that medical devices be developed taking errors arising from risk of use and human factors into account. The IEC 60601-1 3rd edition and specifically IEC 60601-1-6, are examples of international standards that seek to minimize the risks presented by poor usability. The manufacturer is responsible for making well-designed, ergonomic medical devices.

The more natural a medical product is to use, and the easier it is to learn to operate, the safer it will be for patients. As a consequence, better and safer products increase their market competitiveness. Consumer electronics sector Apple’s iPhones are a good example of this. Apple revolutionized the smartphone market by providing an interface that was designed to maximize the user experience, not to force the user to learn the phone’s tricks.

Guidance and implementation of IEC 62366

In the medical electronics world everything is well defined and regulated, and this applies to usability engineering as well. Extensive guidance about how best to minimize the risks with usability engineering is provided in IEC 62366. The 100-page document that defines the standard presents a user-interfaced medical device design cycle comprised of the following steps:

The usability engineering cycle

The following table further describes this usability engineering process, also providing an understanding of how the design cycle steps are designated in IEC 62366:

A critical phase in the usability engineering cycle is the conceptual design. How can we understand the mental model of the user? How can we identify expectations and typical use? A good method is to use the rapid development model: build simple prototypes and simulators from cardboard and duct tape or with software tools, and let users loose. Observe what they expect your model to do or ask them to explain what they intend to do and what they expect to happen. After some repetition you have a much improved concept and are ready to define what functions are critically needed and how users expect them to behave.

Usability of legacy devices

Many of the products that are already in use were not originally designed with usability engineering methods. There is now a proposal to address this and modify IEC 62366. The proposed amendment introduces an evaluation of User Interface of Unknown Provenance (UOUP) and a new Annex K to ensure that engineering processes include usability in legacy devices, minor revisions of devices and standard components embedded in medical devices.

Does good usability just happen?

The popular Finnish mobile game, Angry Birds is in principle just another shoot-and-crash game. What sets it apart is that everything works together seamlessly: .user interface, music, characters, physics modeling and the basic idea all contribute to its overall success and popularity. Medical device design should follow the same principles; make everything easy and natural to use and reward the user when she or he does the right thing!

It is not possible to ensure good usability in a product as an afterthought. Usability engineering must be incorporated from the beginning. It is also necessary to document the process continuously to comply with IEC 62366. While usability engineering is required by the regulations, good usability also offers competitive advantages in a tight market.

In the medical field, good product usability is not just a gimmick, but rather a fundamental safety consideration. As an added bonus it can make your product fun and rewarding to use. When you succeed in providing top-notch usability, everybody benefits: patients, users and your balance sheet.