I'm not sure from the post if the problem is referring to a baby or one of the adult rabbits ...
If it's a baby . . .
It's impossible for us to do anything over the Internet without knowingwhat is wrong with the baby and why the body systems arefailing. It could be anything from a congenitalillness,a viral or bacterial infectionto pneumoniafrom aspirating the formula.
From what you are describing, I doubt that a vet would be able to save the kit.
The best you can do is to keep the baby warm.
If it's an adult rabbit, it may be suffering from pneumonia orcongestive heart failure. Choking is possible if the rabbitis salivating profusely. If this is an adult rabbit, itshould be taken to the vet ASAP as this is an emergency situation thatcannot be handled over the Internet.
If this is adult rabbit that you suspect is giving birth, it may besuffering from internal hemorrhaging - is there any bloody discharge?
Pam