I'm trying to figure out the plausibility of a scenario for a friend here.

Medevac flights are prohibitively expensive, and I was wondering if it is possible to work with the airlines to "roll your own" commercial stretcher type medevac scenario? Does anybody here have familiarity with how airlines handle passengers in a litter/ on a stretcher?

Here's the scenario: An EU national from eastern europe was in her home country and suffered a broken pelvis/hip and head trauma in an auto accident. She is in stable condition since emerging from a coma. Her Fiance (an American) has flown over there, and is finding that her country's health care system will not provide her with the care she needs. If the Fiance could arrange for an MD and some RNs from his circle of friends to come from the States to accompany the patient, how difficult and expensive would it be for him to arrange his own medevac using a stretcher on a commercial flight? What are the requirements? I know stretcher passengers are regularly accommodated on international commercial flights.

This is assuming the legalities with travel visas have been covered.