Considering this past incident, I would think that there should be two packs in each cabin:
1. A medical kit: bandages, epi pen, aspirin (for heart attacks), etc...
2. A 'survival kit' for being stuck: water, bags of dried snacks, glow sticks, pee bags, etc...
Then, to alert CMs/EMS, each pack should set off a silent alarm which is a blinking light on the outside of the cabin. Pulling out the survival kit causes a blue light blinking; the medical kit, a red light blinking. The light can't be turned off by the guest by putting back an emptied pack.
This will let CMs know as a cabin comes in what was done. If the cabins are stuck on the line and there is a medical issue, they can pull out the med kit to start the red light blinking to alert EMS. Or even if the line isn't stuck, a pulled med kit let's the CM know which cabin has the medical issue.