According to author Stephen Wilcox (Chair of IDSA Human Factors section), ethnographic research is now common in medical device development. The majority of this research is of course, qualitative, and primarily focused on identifying opportunities:
"Much so-called ethnographic research—perhaps most of it—is designed simply to generate ideas, that is, to stimulate creativity. Inevitably, when members of device-design teams go into the field and see directly how their devices and other devices are used, it generates insight and stimulates new ideas."
But there is another type of ethnographic research that is as much about the validity of findings as it is about generating ideas (Sidebar: simply put, in research, validity refers to the degree that you are actually measuring what you are intending to measure). Typically validity is associated with quantitative measurement based methods such as performance testing. But Wilcox suggests several ways to increase validity in ethnographic research including careful sample selection, quantitative measurement and objective data recording. This more robust approach to ethnographic research comes with a price:
"conducting such research is difficult, time-consuming, and, frankly, expensive, in comparison with the idea-generation type of ethnographic research."
It's unlikely that most organizations will be able to accommodate all of the steps necessary to conduct highly valid ethnographic research - especially since many are just getting into the practice of doing any field research regularly. But Wilcox's recommendations should really be taken as best practices for conducting any type of user research effort (whether validity is an explicit intention or not). For example, making sure that the "sample accurately reflects the population of interest" is a fundamental research planning step. The deeper challenge when addressing validity is knowing what you know - for example determining whether your sample is truly representative.
The February MD&DI issue also contains an article on considerations for designing medical devices for home use, and another article on integrating human factors into the medical device development process.
Finally, for a less technical, down to basics overview of ethnography, see Design Meets Research, from GAIN, AIGA's journal of business and design.