What a horrific experience to have to live through. I'm so sorry for your loss.
This is going to sound much more harsh than I mean it to, but the law is sometimes harsh and cold.
Do you have MEDICAL evidence that but for the actions of the EMT/ambulance company, your son WOULD HAVE lived? Not, MIGHT HAVE LIVED but WOULD HAVE LIVED?
Two things I am tired of typing: 1.) A wrongful termination does not mean that you were fired for something you didn't do; it means that you were fired for a reason prohibited by law. 2.) The above answer, whatever it is, assumes that no legally binding contract or CBA expressly says otherwise. If it does, the terms of the contract apply.