Emergency Alert Systems
The most critical application of GPS technology in health services is in emergency alert systems. For situations where you're alone, disabled or otherwise can't get to a phone in time to call for help, these are potentially powerful lifesaving devices.
These systems generally consist of a few parts. There's the main component which you wear, such as a wristwatch or a necklace, or a specially designed “safety phone." This is the piece that does the GPS tracking, and that you activate to call for help. Some systems also have features such as a charge station or a signal relay station. Features of individual systems may vary, but may include anything from emailing out your position at the time of the emergency to loved ones, calling your family members, activation upon a lack of heartbeat, fall detectors, geofencing, and others.
These systems do not rely exclusively on GPS tracking capabilities, also making use of local cell networks for even more accurate triangulation of the signal where possible. As you might guess, most of these systems require a subscription of some sort, as well as a one-time hardware purchase.
For an excellent overview of one such set up, the MobileHelp medical alert system, check out this CNET article.
For other examples of medical alert systems, check out companies such as Brick House Alert, 911 Anywhere, or LifeWatch.