Though the legal wrangling in the Terri Schiavo case has been loud and contentious, the brain-damaged woman's physical response to having her feeding tube removed is likely to be very serene.
"The process of starving to death seems very barbaric but in actuality is very peaceful," said Dr. Fred Mirarchi, assistant clinical professor of emergency medicine at Drexel University College of Medicine in Philadelphia.
"The patient's experience is really pretty benign," said Dr. Joanne Lynn, a hospice physician associated with Americans for Better Care of the Dying, a group working for improved end-of-life care. "Overwhelmingly, what will happen is nothing."
Lynn, who has worked with numerous families facing end-of-life situations, said most patients who are removed from life support will die within a matter of a few days or weeks.
"Some people can last four or five days -- some people can last 20 days," she said.
Schiavo's feeding tube was removed March 18 following a contentious battle between her husband, who said his wife would not want to live in a vegetative state, and her parents, who wanted her kept on life support.
Schiavo's feeding tube was removed twice before, in 2001 and 2003. The second time, the tube was replaced after six days when Florida Gov. Jeb Bush signed a hastily passed law allowing him to intervene in the case. "Terri's Law" was later ruled unconstitutional.
The Body Begins Shutting Down
The physical process of dying after life support is removed follows a pattern familiar to hospice workers. And the fact that Schiavo is in a vegetative state will likely make her death faster and less painful, Lynn said.
"It depends on whether she has the ability to swallow anything -- and if that anything is offered," she said. "If she's unable to swallow anything, the course toward dying, so far as anyone can tell, is fairly comfortable."
Most patients who cannot eat or drink will enter a physical state known as ketosis. During ketosis, the body begins to use fat and muscle as a fuel source.
In advanced cases of ketosis, the nervous system response is dulled, and patients rarely feel pain, hunger or thirst. There is also some evidence that ketosis can produce a state of well-being or mild euphoria.
Family members and friends are often surprised to find that a terminal patient's eyes will open and they will appear to glance around the room. "It's very confusing on an emotional level," said Lynn.
But Lynn explained that the part of the brain controlling eye movement is actually very primitive and can remain active even after other parts of the brain appear to have stopped functioning.
Patients are also likely to experience irregular breathing.
"Cyclical breathing is very typical," Lynn said, adding that in some cases the patient will breathe very rapidly, then take just one or two breaths per minute.
Over time, the patient becomes more and more dehydrated, stops discharging urine and eventually develops kidney failure. When this happens, death is generally a few days away.
"Patients at this point are uremic -- filled with bodily toxins -- and are unaware of their surroundings," Mirarchi said. "They develop electrolyte imbalances that eventually cause an abnormal beating of the heart."
In the final moments of life, the abnormalities in the patient's heart rate known as arrhythmia are common.
"The heart will then stop and the patient will die," said Mirarchi.
The efforts of caregivers may in some cases complicate the death of the patient. Giving a patient water, for example, may prolong the process.
"Going without water makes it more gentle," Lynn said. "Allowing chemicals [in the blood] to cause arrhythmia is more merciful."