I never post so I’m sorry if this is the wrong place/etc
Caligula and his coma has been asked about before, but received no surviving responses. In the meanwhile, I did turn up some answers regarding comatose care before modern medicine:
A now-deleted user offers the medical side of things in this thread.
u/jpallan offers insight on Henry VI in this thread.
And bonus: u/itsallfolklore has a post on how the comatose were socially regarded; not directly medical, but related and interesting.