Medical device design is primarily focused on treating problems, not on preventing them. In the future, containing health care costs will increasingly rely on maintaining wellness rather than curing once a problem has arisen. Also increasingly, people will be involved in managing their own self-care. Rather than individual medical devices, they’ll need an integrated system that is customizable to their needs. Here is an interesting article addressing this issue: http://interactions.acm.org/content/?p=1367.