In this case, the "Press Don't Panic" tool is a real life-saver for such emergency situations. The small deice works like a voice recorder that records audio information and stores it for playback when it becomes necessary. For example, if you know that you have severe allergy, you can record instructions on actions that should be taken in case you have a severe reaction. This information will be valuable for anyone, who does not have medical training and can help them deal with the emergency right away.
There is only one button to press on the "Press Don't Panic" device, so this should be clear in case of debilitating event. The recorder can be clipped to the belt, bag or your clothes, where it can be easily seen by other people.