Not this kind . . .
It's a simple concept: Just store the number of the person you'd want notified in case of such an emergency under the heading ICE. Or ICE1, ICE2, and ICE3, if you have several. Evidently, hospital personnel and emergency responders of all types are aware of this code.
Of course this isn't a substitute for having similar information in your wallet and you may be one of the dwindling few who doesn't even have a cell phone --but if you do -- this might be useful.
Or you may already know about this -- the young woman whose phone I borrowed for this picture (my cell phone stays in the car) showed me that she had ICE numbers stored in her directory.