At first I wanted to have him be concussed and not treated immediately, but is that type of coma more likely to cause lasting after-effects (I don't want any, or at least the minimum)? At first I also wanted some kind of traumatic chest injury which would introduce defibrillation into the story, but I reconsidered, as the character is a singer, and I didn't want anything which affected lung capacity in the long run.
So, coma. Would he be on a respirator? What about naso-gastric intubation? Even though I'm writing an unrealistic premise (yes, the Flashforward crossover is still kicking my ass), I like the details to be realistic!
I have googled for: coma, aftereffects of week-long coma, and tubes in nose.
ETA. Thanks everyone, you've all been really helpful!