From The Ergoweb® Learning Center

New Standard for Ergonomics in Medical Device Design

The American National Standards Institute (ANSI) and the Association for the Advancement of Medical Instrumentation (AAMI) have released a new standard relating ergonomics and human factors to the design of medical devices. The 40-page standard, developed by the AAMI Human Factors Engineering Committee, describes design approaches and techniques, training programs, and learning tools to help manufacturers interpret and satisfy relevant national and international regulations and to make devices safer, more effective, and easier to use. “Good design should not only reduce the likelihood of use errors but also, when use errors do occur, increase the likelihood of their detection and correction and increase the ability to mitigate their consequences,” the standard states.

How does ergonomic/human factors relate to medical devices? Humans have known capabilities and limitations. Ergonomics in the design of equipment seeks to match both capabilities and limitations to the design. When these are not matched, medical devices may be used improperly, data interpreted incorrectly, or inappropriate action to an alarm might take place. All these consequences could, ultimately, affect a human life. The following table taken from the standard gives some examples.

Table 1 – Sample of design flaws and associated use errors

Example of design flaw: Possible resultant use error:
Push buttons on a control panel are too closely spaced. User presses the wrong button.
Two icons on a software screen look too similar. User misinterprets the icon and selects the wrong function.
A user interface requires a complex, lengthy, and arbitrary sequence of button pushes to initiate an infusion. User enters incorrect sequence and fails to initiate infusion.
Infusion pump displays misleading “Open Door-Reset” message when air is in the infusion line. User repeatedly opens the door and presses the rest key instead of clearing air from the infusion line.
User-adjusted high and low alarm limits on a heart-rate monitor are not continuously displayed. User fails to detect a dangerous increase in heart rate because alarm limit is set too high and user is over-reliant on alarm system.
Typical user-applied force exceeds breaking strength of catheter connector. User cracks catheter connector when tightening.

The AAMI Human Factors Engineering Committee, which is co-chaired by Carl Pantiskas and Matthew B. Weinger, wrote the document to ensure that it is easy to use and understand by a broad audience, including medical researchers; design and engineering personnel; marketers; and product, department and company managers.

Developer Carl Pantiskas is no stranger to ergonomics/human factors in design. The medical device manufacturer he currently works with defined a core human factors design for patient monitors back in 1983. That’s 17 years before the general public heard terms like ergonomics and human factors from the Occupational Safety and Health Administration (OSHA).

Ergoweb was able to catch up with and ask him a few questions.

EW: You were recently part of a committee that wrote HE74 ‘Human factors design process for medical devices’. How did you become interested in this area?

CP: My interest in human factors for medical devices began when I was working on my MS degree in Biomedical Engineering in the early-mid 1980s. Shortly after I started working for my company (Spacelabs Medical) in 1986, my company discovered that I had an innate feel for our product’s human factors (I kept pointing out aspects of our product’s human factors design that wouldn’t make clinical sense to our target user). In 1988, AAMI published recommended practice ANSI/AAMI-HE-1988 that covered issues related to human factors of medical devices and facilities. I joined the AAMI committee shortly after that. From 1988-1993, the committee revised HE-1988 to provide greater detail overall and add new material on alarms for medical devices and medical devices with human-computer interfaces. This revision also lightly touched on the medical device design process and the need to understand the target user. This document was published as ANSI/AAMI HE48-1993. Activity of this AAMI committee basically ceased until 1997-1998 when Dr. Matthew Weinger and I became the committee cochairs.

Between 1993 and 1998, the U. S. Food and Drug Administration became increasingly interested in reducing errors/injuries that arise due to questionable human factors designs. In June 1998, at the first meeting of AAMI’s reconstituted committee, the committee’s FDA representative, Peter Carstensen, surprised the committee when he mentioned that an international working group had proposed creating a standard that described the human factors design process. Was there an event in your career which a standard such as this may have addressed? It was obvious to me within 15 minutes of the start of the meeting that our next task would not be revising HE48-1993. It would, instead, be creation of a realistic process standard related to the human factors design of medical devices. I came to this conclusion because I realized that a poorly written process standard could close every medical device manufacturer.

EW: What figures and examples do you use when discussing the cost benefits of error prevention to a manufacturer and end user?

CP: I don’t spend much (if any) time doing things like this. I spend more of my time trying to figure out how we can: Do our job as unobtrusively as possible (e.g., don’t get in the end user’s way)? Minimize the amount of time someone spends using our product (thereby, maximizing the amount of time they can spend on hands-on patient care)? Design things so that we can’t possibly confuse users?

EW: Are there any other points on the matter of ergonomics and error reduction that you feel would benefit our readers?

CP: The general concept of ergonomics and error reduction is straightforward – if it works the way you expect it to work, then you probably won’t screw up while using it. Within the arena of healthcare, knowing who will use your medical device, how they approach using it, and what things affect their use of your device all impact how they expect the device to work.

EW: Thank you very much for your time in this.

The FDA is expected to recognize HE74:2001.

The standard, “Human factors design process for medical devices” HE74:2001, is available for $95.00. To order a copy from AAMI, call 800-332-2264, ext. 217.