I thought that this article is interesting and telling with respect to how the FDA will assert it regulatory authority regarding usability issues. Here are a few quote from the article.
Recognizing that more patients of all ages are being discharged from hospitals to continue their medical treatment at home, the U.S. Food and Drug Administration announced an initiative to ensure that caregivers and patients safely use complex medical devices in the home. (My emphasis.) The initiative will develop guidance for manufacturers that intend to market such devices for home use, provide for post-market surveillance, and put in place other measures to encourage safe use of these products. The FDA is also developing education materials on home use of medical devices.
These home care patients often need medical devices and equipment such as hemodialysis equipment to treat kidney failure, wound therapy care, intravenous therapy devices, and ventilators.