I'm not sure this is actually helpful. If the cryonics team isn't anywhere nearby having this information may very well translate close to "well, we're not getting that one."

Good thing there are telephones, ambulances and the possibility for neighbors or nearby friends to be emergency contacts. Add an enormously loud physical alarm to the device and anyone dying in their sleep who isn't living alone can have immediate attention of their housemates or family.

I'd expect such a system to occasionally save lives even apart from cryonic considerations and there would be a whole bunch of people who get chilled more rapidly.