Good info for ordinary passengers, physicians, nurses, EMS people, etc.: The Clinician's Guide to In-Flight Emergencies
I'd rather be on a flight with an EMS person than with a Dermatologist. Every person should know how to do CPR. The tricky part is knowing when it is needed. If they stop breathing and turn blue, probably yes.
People do die on airplanes, but they probably would have died anyway. Interesting factoid: airplane air has 10% lower oxygen than the air on the ground.