If you’re unconscious on your way to the ER after a car accident or other major accident, there’s a good chance there will be police at the scene as well as paramedics. They would secure your firearm if it’s found at that point.
Maybe we should wear med-alert bracelets: Allergic to penicillin and Carries a firearm. 
(Yes, I’m totally kidding about the med-alert bracelet for the firearm. 
)
UPDATE: The ever-knowledgeable, Ed Combs, Senior Editor of The Concealed Carry Magazine, had the answer:
This will almost always be handled by EMS; the chances of you getting back-boarded and gurneyed into an ambulance without them either removing your pants entirely or enough of your pants to notice a firearm are diminishingly small.
(Assuming you’re unconscious and can’t tell them you’re carrying.)