In this case a different approach would have been far better preparation. Around here there are two systems for it.
A group of people make contact via phone daily. If a member doesn´t call or doesn´t answer the partners assume an emergency and react.
For the other system you have a signal device that alerts a medical service when you trigger it. You have to confirm twice a day that you´re still ok (just pushing a buttton). If you forget you´ll be reminded by an annoying sound. If you fail to confirm, the service assumes an emergency and sends a responder.
Both systems require that you tell someone when you leave for a couple of days.
Both system were designed to help disabled or eldery people.

BTW: I don´t know any person who showers with a whistle around the neck.