Many passengers don't realize there has always been help available for people with serious medical needs on commercial flights. People forget that flight attendants are not just there to serve them drinks. They are considered a safety officer & serve a vital role when any passenger get sick in flight. When passengers get sick you can't just pull over at the nearest hospital.
Basically, all flight attendants are trained in the basics of first aide. But, they are also trained into looking for the symptoms of stroke victims, & heart attack victims. All airlines are required to have AED or heart affribulator on each aircraft for heart attack victims. Flight attendants go through training yearly on its use. Then for worst situations, flight crews have med-link at their disposal. Med link is a medical facility staff with doctors in every specialty that's always on call for any medical emergency in flight. How it works? The flight attendant with fill out a form of vital signs on a passenger. They will then submit this form along with the passengers name to the Captain who will in return speak to a doctor at med link. The med link doctor is in charge at this point & will make a decision rather the Captain should continue the flight, or make an unscheduled medical emergency to the nearest airport with adequate services.