I work in a trauma ICU and have seen the following situation play out many times. When one is initially injured the emergency response system kicks in, EMTs arrive, you are shuttled to the ED, sent to surgery if you are stable enough, and then brought to the ICU. Now all of this happens because the level of injury and permanent damage isn't known until the treatments have been done. You save the life and ask questions later. Your loved ones do everything possible to save your life and hope for the best. Days or weeks later, you wake up on the ventilator. If the injury is low enough, sometimes a person doesn't have to be ventilated and has complete upper body movement (para vs quad).
Here's the kicker... I have seen hard working, hard living men - the very kind who said absolutely no way do I want to be kept alive (before the accident) go for the full court press once they are awake. They are pissed off and depressed, sometimes with no movement below the shoulders and ventilator dependent, yet the WILL TO LIVE is so strong that inevitably, virtually everyone who survives decides to do everything possible to live. This year we have sent two such guys to the Craig Institute in Colorado for rehab. The last guy had a high C2 injury who asked to be taken off support when he first woke up. Days later as the process went on, he decided to continue.
The problem is there is no time out process after the injury to ask the "do we keep this person alive question." You have to do everything possible initially and then only after someone wakes up does the process of evaluating the future begin. It's horrible dilemma either way, because you want the person to live, but then they live with the consequences once they are awake.
Even then, Superman died from bedsores.
And yes, Gordon, good point... whether or not the mind is intact has everything to do with how decisions are made.