They used to be very common. AirEvac in PHX used to be known as Samaritan AirEvac, as it was owned by Samaritan healthcare and at one time was the busiest hospital-based EMS operation in the U.S. and using 4 MBB BK-117s....great helos for EMS.
Before Samaritan divested it, and it was sold to PHI. They started in 1969 with FW only, using 2 Cessna 402s, later 414s, and even later 441s. With the FW being contracted by Sawyer Aviation at PHX.
Added their first helo in 1979, an SA316B, and later an A109 and AS355, before replacing them with 2 AS350B helos. And kept expanding from there to the largest in the nation in the 1980s and 1990s.