Persistent Vegetative State

Persistent vegetative state is a medical syndrome produced by brain damage. In persistent vegetative state, the patient is awake but does not demonstrate cognitive ability and shows unawareness of the self and the environment for at least 1 month. The person demonstrates no purposeful, sustained, or voluntary behavioral responses to visual, auditory, tactile, or noxious stimuli, and there is no language comprehension or expression. There is bladder and bowel incontinence and preserved cranial nerve and spinal reflex function; sleep–wake cycles may be normal. The state often occurs following coma and is caused by traumatic brain injury or oxygen deprivation. The term persistent vegetative state may be somewhat misleading [Page 802]in some cases. In the United Kingdom, the Royal College of Physicians recommends using the terms vegetative state, continuing vegetative state, and permanent vegetative state to distinguish between early and late stages of the syndrome, and because the patient may, indeed, recover, at least partially.

Clinical Features

The brain represents only 2#x0025; of body weight but accounts for 20#x0025; of oxygen utilization. Lack of oxygenation (anoxia) for more than 2 to 4 minutes leads to rapid destruction of brain cells; the extent of injury increases with the duration of oxygen deprivation. Extensive brain damage results in brain death, and somatic death follows rapidly. The development of cardiopulmonary resuscitation (CPR), artificial respiration, and other technologies has made it possible to keep people alive after motor accidents, drowning, and cardiac arrest. Because CPR can keep the person alive for long periods of time, different levels of brain damage and consciousness can occur, depending on the duration of anoxia during the resuscitative process. If the person survives, extensive brain damage sometimes leads to a partially conscious state without purposeful behavior inconsistent with a sapient existence. This particular condition was first named persistent vegetative state (PVS) in 1972 by Jennett and Plum. It is different from brain death where there is no consciousness, motor function, or electroencephalographic activity.

There are several states of altered consciousness that may be confused with PVS. Coma is a state of unconsciousness that may or may not be reversible and can occur with or without brain damage. Minimally conscious state (MCS) is a condition distinct from coma and PVS with inconsistent and erratic responsiveness that may last for years. Generally, MCS has a better prognosis than does PVS. It is also different from locked-in syndrome, in which the patients are aware of the self and the environment but have lost motor function and speech.

Brain Death and the Definition of Death

Brain death is a state of irreversible destruction of the brain. Criteria for diagnosis include deep coma and absence of any brain-stem functions (e.g., spontaneous respiration, pupillary reactions, gag and cough reflexes). Hypothermia, drug overdose, and poisoning should be excluded. Electroence-phalography is useful, but not essential, in determining brain death.

For centuries, the diagnosis of death was based on permanent cessation of breathing and the heart beat. Because of technological advances and ethical and legal implications, a restatement for the traditional definition of death was needed. A presidential commission was formed, and in 1981 it issued a report on the definition of death in the United States. Because of ongoing changes in technology, increasing sophistication in medical knowledge, and refinement of techniques, the definition of death was based on clinical physiological standards rather than solely on medical criteria and tests. This statutory definition was to be kept separate and distinct from provisions governing criteria for organ donation and termination of life support. The report does not deal with the medical, legal, and ethical issues in brain-damaged or dying patients.

...