If Terri Schiavo (search) dies from the removal of her feeding tube, her passing should be peaceful, experts say.
After all, she is in a persistent vegetative state without conscious awareness, they noted.
But studies show that even patients who can speak and who have chosen to stop eating and drinking generally don't complain of thirst or hunger, said Dr. Russell Portenoy, chair of palliative care at the Beth Israel Medical Center in New York.
"It's as if the body has a protective mechanism at the end of life, such that loss of appetite and loss of thirst precede the dying process," he said.
Death can take a widely variable amount of time but generally arrives within three weeks, Portenoy said.
Schiavo's feeding tube was removed on Friday. It has been removed twice before and then re-inserted because of legal pressure, but Portenoy and Yale expert Dr. Sherwin Nuland (search) said those interruptions in feeding should not have caused harm.
Generally, death from prolonged lack of food and water is due to dehydration, said Nuland, author of the book, "How We Die."
Dehydration leads to kidney failure. When the kidneys shut down, levels of certain substances in the blood rise. The person slips into a coma (search). At some point the biochemical changes in the blood become severe enough to impair the electrical system that controls the functioning of the heart, and the heart stops beating.
"It's usually quite a peaceful death," Portenoy said. "The person generally looks as if he or she is drifting off to sleep, and then dies."