I just read a posting where somebody wrote it’s not possible to track helicopters. Since helicopters obviously affect air traffic control, could somebody please explain this? Is there a way medical centers could identify and track medical flights, fixed wing and rotor?
They’re usually not IFR, so we can’t track them.
When they do go IFR, they often use the ident AIR1.
Most (dare I say all?) medical helicopter flights are flown VFR and are not trackable.
Other flights operating in the ‘system’ can be identified by the “lifeguard” callsign. There’s a place here on flightaware to display just lifeguard flights: here
(it’s found by going to the “live tracking” page, and then “special humanitarian flights” link.
Thanks mduell and cfijames! 
I just clicked the link cfijames supplied and found a flight to KRST (my locale). Also tracking a lifeguard flight from KGRB to KRST (N5494R). It is listed in red (font) as you mentioned. Would be nice to have it in red on the maps as well.