Tim,
USCGA was running medical ops through 171.2375 PL 151.c, and they were then handled by NLFD, Wtfd and L&M on the Wtfd trunk system. I don't think Wtfd was ever actually on scene, I know they were cancelled at least twice. I believe the first responders are EMT cadets and during the Graduation USCG Corpsmen.
In general they show up on the same channel as police.