"So how should that determination be made?"
That's a good question.
When the heart stops beating, you know for sure, and other vital signs. I'm not an expert, but I do know that I would get many opinions and do much research if doctors were too quick to say that my loved one was "brain dead."
In my research one person that I would e-mail is wesleyjsmith.com, and as pro-life as he is, even he would not be my ONLY deciding factor for a loved one.
Also, please read T'wit's really informative post #160.
So you don't know. And since you don't know, well, then I suppose we have have to keep people alive forever on machines.
Yep, despite the patient's wishes, despite the emotional and financial cost to the survivors, Sun says that we should keep the loved one alive as long as science allows, since we can never "really be sure".
Good answer. Thanks a lot for your contribuition to the thread -- which obviously consists of nothing more than telling people how they're wrong without saying what's right.
Baby Daniel was pronounced "almost" brain dead, not by doctors (who would not use such a term among themselves) but by state bureaucrats. That often means they want to cut him up for his organs. Very profitable business.
"Almost" brain dead doesn't mean anything, medically. "Brain dead" doesn't really mean "dead," either. It means a comatose, unreflexive condition thought -- thought -- to be irreversible.
The tests for it are quite horrible. The patient is banged around brutally (people who have watched it tell me they cringed). The docs try to cause pain, put ice water in the ears, shine bright lights in the eyes and suchlike. (See this site for a detailed discussion, especially the warnings and pitfalls: Testing for death by brain criteria. ) The tests are to insure (as best we can) that the patient is utterly unresponsive in brain function. (For my two cents, the stricter the standards, the better.)
Note that one of the criteria is lack of brain-stem function, meaning that the patient cannot breathe unaided. A patient who can breathe is not "brain dead." Karen Ann Quinlan was not "brain dead." Neither is Sunny von Bulow, possibly the victim of attempted murder by insulin poisoning in a famous case in 1980, who is comatose but is still alive and lovingly tended all these years later.
In the end we don't really know. It is impossible to test a brain from the outside and find "mind" on the inside. Mind is and always has been a mystery. It is certainly possible that "brain dead" patients are aware of their surroundings. Occasionally one of them wakes up and says so. Perhaps such a person was a misdiagnosed case in the first place and the others are truly "mind dead." Perhaps not. We don't know.