If there's an in-flight medical emergency (at least on a US carrier) a page will be made for medical assistance. Typically, there's at least one medic/nurse/EMT on board willing to assist as a good Samaritan, and they will work with the flight crew and medlink. Often you will be rewarded with points or miles as a thank you for your humanly kindness. If you believe this should get you free airline upgrade beforehand, then one might question your moral intentions; and we should first upgrade teachers, fire-fighters, counselors, nurses, flight attendants from other airlines... you get the idea.