Sometimes a modern marvel isn't a thing, but a way of doing things.
In the 1950s or 1960s if you happened to find yourself shot in the U.S. and taken to a hospital "emergency room", you would meet a doctor. In the practice of the time, you were equally likely to be treated by a doctor who had been in a M.A.S.H. unit in Korea, or a dermatologist.
In the late 1960s a number of doctors in Alexandria, Virginia, decided to organize their emergency room to assure optimal treatment 24 hours a day, seven days a week. In the course of defining "optimal treatment" they pretty much invented the specialty of emergency medicine. The "Alexandria Plan" caught on across the country and by 1979 the specialty was officially recognized.