I am sure you have seen this, but it is still worth commenting on. A 13 year old California girl suffered tragic complications after undergoing sleep apnea surgery and was declared brain dead by the physicians at the hospital where the surgery was performed. Her family has contested the "brain death" declaration and has had her transferred to an disclosed facility with beliefs similar to theirs.
Two major points (no snark with these horrible circumstances):
1. Adults can avoid the ramifications of a similar situation by executing a living will about their intentions if declared brain dead and by designating a health care surrogate to act in their stead via a health care power of attorney.
2. The declaration of intent and designation of a surrogate are only as good as the person tasked with carrying out one's wishes. Be sure that the surrogate shares one's intellect and values, and respects one's wishes.