The Religion Link website has an interesting discussion going on about what constitutes brain death and the end of life.
Here's an excerpt or read the whole thing:
Caring for people in the final stages of life is one of the most expensive aspects of the nation’s health care system, accounting for as much as one third of all health care costs, and about 30 percent of Medicare expenditures come in the last year of a patient’s life. Moreover, modern medicine is able to keep human beings — or at least their bodies — alive for increasingly long periods, often in what is known as a “persistent vegetative state,” or PVS.
All of these developments are posing increasingly complex challenges for religious traditions trying to adapt to new insights on the brain and new questions about consciousness and the moment of death. Ethicists also raise questions as to what is the moral use of limited health care resources — on helping the dying or saving the living.