Brain death and coma are not the same. Often confused, even by health professionals and judges, a “persistent vegetative state,” such as that of Terry Sciavo implies neither cessation of brain function or irreversibility, both basic criteria of brain death. These criteria are codified in the Uniform Definition of Death Act, now recognized in all of the fifty states.
Coma is a neurologic condition in which much of the brain function is impaired and results in degrees of unconsciousness and loss of many basic reflexes and homeostatic activities, such as breathing. This condition may be caused by trauma, hemorrhage, biochemical abnormalities such as hypoglycemia or low blood sugar. Another common cause is intoxication with alcohol, barbiturates, opioids and numerous other substances. In most cases there remains some baseline brain activity detectable with an electroencephalogram (EEG)--most, but not all. So a flat-line EEG is not enough to establish brain death. Further, in all the above cases the condition is reversible, at least potentially.
In Terry Schiavo’s case, EEGs were found to be active in every instance. But, we didn’t need an advanced medical device to make the case that there was brain activity. We all saw the videos of her smiling at her family’s faces, reaching toward balloons, and following people about the room with her eyes. She most certainly suffered significant loss of cerebral function, but she did not lack brain activity and she was not shown to be in an irreversible state, i.e., she was not brain dead (and, she was not comatose). She was pronounced to be in a “persistent vegetative state,” a condition newly coined and nebulously defined. Wikipedia summarizes the conditions thus: “A persistent vegetative state (PVS) is a condition of patients with severe brain damage in whom coma has progressed to a state of wakefulness without detectable awareness.” You don’t have to be a medical ethicist or Harvard neurologist to see how subjective such a definition is.
Brain death is an important legal definition in light of modern technological advances in medicine where we can literally keep an individual’s heart beating indefinitely, long after the brain function has irreversibly ceased. The determination of brain death may include serial EEGs over several days, physical exam findings that demonstrate loss of brainstem function, and, most recently, nucleotide blood flow scans that can reveal the loss of bold flow to the brain. If there is no blood flow for even a short period of time there can be no life and thus no reversibility. I am reminded of a passage in Leviticus “…for the life of all flesh is its blood. (17:14)
Great strides have been made in medical therapeutics using tissues or organs from living or deceased donors. In some cases, such as the heart, organs for transplant can only come from donors determined to be “brain dead,” with the heart still beating, but all signs of brain function and hope of reversibility sadly lost.
There are wonderful and amazing stories of people in comas for years one day awakening and going on to complete or near complete recovery. For this reason, coma should never be a sole reason for discontinuing life support and must never be confused with the situation in which organs may be removed for transplant. It is literally the difference between life and death.
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Tuesday, March 04, 2008
Coma, PVS or Brain Death?
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