Start With Two Minutes.
You don't have to build an elaborate family emergency system tonight.
Create two accurate ICE contacts. Complete the Medical ID or Emergency Information already built into the phone. Then, when you have a little more time, create Smart Contacts for the people you may need to help and connect them to complete medical forms you can reach from your phone.
Add wallet cards and QR codes where they make sense. Keep a downloaded copy for offline access. Give the right information to the right caregivers.
And because phones die, networks disappear and technology occasionally chooses the worst possible moment to become interesting, keep a paper fallback too.