If a has cardiomegaly & lungs filled with water & is on oxygen support what are his chances to survive if oxygen is removed?

Critically ill: Sounds like your loved one is critically ill. I'm sorry to hear that. You're describing multiple organ dysfunction (heart, lungs) which is never good. By oxygen, do you mean a breathing tube? The decision to remove a breathing tube comes down to 2 things. 1: they will only remove it, if they expect the person will do well 2: or, they expect the person to die and keeping the tube in is futile.