"Eating and drinking are pretty complicated actions. In order to eat and drink and swallow properly actually requires several parts of the brain's circuitry," including the cerebral cortex and thalamus, Albin, the University of Michigan professor, said.
Bernat, the Dartmouth neurologist, said certain reflexes that assist in eating and drinking are controlled in the brain stem, "but voluntary control over the mouth, jaw, and tongue, and chewing and the initiation of swallowing—all necessary functions to eat and drink—are voluntary movements controlled by the cerebral cortex."
To keep Schiavo alive after her 1990 cardiac arrest, doctors inserted a tube to her stomach that provided nutrients and water. A court ordered the tube removed on Friday, March 18.
According to Schiavo's husband, Michael Schiavo, Terri Schiavo did not wish to be artificially kept alive if there was no hope she would recover from a vegetative state. He has argued in court since 1998 for the permanent removal of the feeding tube.
Schiavo's parents, Mary and Bob Schindler, have argued in court that their daughter shows some signs of awareness and could recover some of her mental capacity with therapy. State and federal courts have consistently sided with Michael Schiavo.
Dehydration
According to Bernat, PVS patients without a feeding tube suffer the same fate as any other patients who cannot eat or drink.
"The patient becomes progressively dehydrated. Once the dehydration reaches a critical level, blood pressure begins to drop. Once blood pressure is too low to adequately [supply blood to] the coronary arteries, the heart stops and the person dies," he said. Albin added that the dehydration and subsequent increase in sodium levels causes the kidney to cease functioning.
After a day or two of without food, the body initiates a process called ketosis. Abnormally large amounts of compounds called keytone bodies accumulate in the blood. This ketone buildup is thought to suppress hunger pangs.
But because PVS patients are unaware, neurologists believe the patients feel no hunger—ketosis or no ketosis. Neurologists also say that PVS patients feel no other forms of pain or suffering, including thirst.
"To suffer or feel pain, there needs to be sufficient cerebral activity to perceive a stimulus as unpleasant," Sigsbee said. "In PVS that neural integration does not exist."
According to Bernat, hospice nurses and doctors say that terminally ill, dying patients who do not eat or drink do not suffer. "They are given mouth care—moistening of dry mouth—and sometimes medications if they are restless. But they usually die very peacefully," he said.
Despite the general consensus that people in a persistent vegetative state feel no bodily pain, Schiavo's caregivers at Woodside Hospice recently began administering the painkiller morphine to her. "Since some relatives claim she is not in PVS, this practice reassures them she will not suffer," Bernat said.
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