Medical Device & Diagnostic Industry

Product Development

Insight

source of design guidance and test methodologies. Engineers experienced in user-centric design will use the standard as an additional source of guidance, complementing their accumulated knowledge and judgment. Less-experienced engineers or their organizations may see the standard as learning tool. On the negative side, organizations that have already institutionalized good human factors practices might see the new standard as yet another set of design criteria to fulfill and one that makes more work without clear benefit.” So, according to Stein, the new standard is likely to be welcomed and provide value to many medical device developers, but not all, which is probably the case with similar guidance documents.

as discussed earlier. Caregivers will seek

shortcuts and workarounds if a device

distracts them from more-important

tasks, even if the work-saving strategies

are strongly discouraged by their institu-

tion. Therefore, designers should pursue

opportunities to reduce the time required

for caregivers to learn how to use and op-

erate devices. For example, a high-quality

video complemented by a quick reference

card might shorten the time required to

learn to operate a ventilator. As another

example, a point-of-care blood gas ana-

lyzer might allow a clinician to commence

with data entry tasks while it completes a

calibration check or prepares to analyze a sample.

• Software user interface/menu depth—

Generally, people prefer menu systems that

Workstations should prevent operation

by unauthorized individuals. For example,

therapeutic devices used in critical-care

environments might require caregivers to

enter a special code or press an enabling

button before they can change the device’s

settings, thereby preventing hospital visi-

tors from making adjustments.

• Workstations/functional relationships

—Displays and their associated controls

should be arranged in a manner that em-

phasizes their functional relationship. For

example, gas control valves can be placed

directly below the associated flow rate in-

dicators (flow tubes) to emphasize their

functional relationship.

Again, such guidelines are subject to change based on the AAMI HFE

committee’s review of industry

comments on the draft standard.

Applying such guidelines in the course of a comprehensive human factors design program promises to produce medical devices that • General/consider worst-case are more effective, less prone to scenarios—In the normal course of use errors that could injure pa- product development, mechanical en- tients, and perceptibly easy and gineers purposely drop products to the satisfying to use. Accordingly, floor from table height or shake them AAMI HE75:200X is likely to for hours in a test chamber to see if and benefit people who interact di- how they break. User interface design- rectly with medical devices, in- ers need to perform equivalent tests cluding clinicians, laypersons, and of their designs. In other words, user the healthcare system in general.

Courtesy of HOSPIRA (Lake Forest, IL)

interfaces must be subjected to bad or worst-case scenarios to see if and how This infusion pump is equipped with a touch screen Conclusion they fail…The goal is to see how well that spaces touch targets apart to avoid accidental In his book, The Tipping Point, an untrained or minimally trained user actuation. Malcolm Gladwell discusses performs when asked to operate an un- events that have shifted momen- familiar device; to observe people using a tum in societies and industries. ⁷ In the device under harsh environmental condi- near future, the medical device indus- tions, such as during the nighttime in a try may look upon the release of IEC lurching and vibrating helicopter; to see 62366 as a tipping point. Currently, what happens when people have little time the document appears to be driving to perform a critical and difficult task. By the majority of medical device compa- stressing the user interface, designers can nies to invest heavily in human factors learn how to make it better suited to real- for the first time. The IEC standard world use. Note that minimization of the calls for a comprehensive approach risk of faulty design or use errors causing to the design of medical device user human injury requires an integrated ap- interfaces. Manufacturers that disre- proach that includes rigorous design prac- gard the standard will be placing in tices, usability testing, and risk analysis. jeopardy their regulatory approval

• General/limit user workload — and device certification (obtaining a Caregivers are often overworked, endur- CE mark, for example). But, like its ing vigorous 12-hour or longer shifts, root document AAMI HE75:2001, sometimes several days in a row. This IEC 62366 does not provide user in- explains why some caregivers actively or terface design specifics. passively reject medical devices that cre- AAMI HE75:200X fills the gap be- ate too much mental or physical work, tween good design process and good