Why were United States Mobile Army Surgical Hospitals so Successful during the Korean War?

In the 1970s show "M.A.S.H." it was stated that the 4077th Mobile Army Surgical Hospital, a fictitious amalgamation of actual units in the Korean War, had a patient survival rate of 98 percent. This statement had always been suspect, so my decision was to discovery if this statement was true or Hollywood. In my research, I have found that there were technological and medical improvements, great courage and dedication by the surgeons, nurses and medical personnel that made this statement possible. I also found that historians have not examined this topic in great length, making the project more difficult that I originally planned.