Adopted by the 41st World Medical Assembly
Hong Kong, September 1989
and rescinded at the WMA General Assembly,
Santiago 2005
Preamble
Present requirements of health reporting fails to provide an accurate
estimate of the incidence and prevalence of worldwide individuals
in a persistent vegetative state (PVS). Ten years ago, a prevalence
of 2 to 3 per 100,000 was estimated for Japan. It seems likely that
the absolute number of such cases has risen appreciably as a consequence
of current practices in critical medicine, cardiorespiratory support,
parenteral feeding, and control of infections in severely brain
damaged patients. How to deal with this emotionally painful, financially
costly, and generally unwanted outcome of modern medical treatment
is an increasing problem.
Persistent Vegetative State
Pathologic loss of consciousness may follow a variety of insults
to the brain including, among others, nutritional insufficiency,
poisoning, stroke, infections, direct physical injury, or degenerative
disease. Abrupt loss of consciousness usually consists of an acute
sleep-like state of unarousability called coma that may be followed
either by varying degrees of recovery or severe, chronic neurologic
impairment. Persons with overwhelming damage to the cerebral hemispheres
commonly pass into a chronic state of unconsciousness called the
vegetative state in which the body cyclically awakens and sleeps
but expresses no behavioral or cerebral metabolic evidence of possessing
cognitive function or of being able to respond in a learned manner
to external events or stimuli. This condition of total cognitive
loss can follow acute injuries causing coma or can develop more
slowly as an end result of progressive structural disorders, such
as Alzheimer's disease, that in their end stages also can destroy
the phychological function of the cerebrum. When such cognitive
loss lasts for more than a few weeks, the condition has been termed
a persistent vegetative state (PVS) because the body retains the
functions necessary to sustain vegetative survival. Recovery from
the vegetative state is possible, especially during the first few
days or weeks after onset, but the tragedy is that many persons
in PVS live for many months or years if provided with nutritional
and other supportive measures.
Recovery
Once qualified clinicians have determined that a person is awake
but unaware, the permanence of the vegetative state depends on the
nature of the brain injury, the duration of the period of unawareness,
and the estimated prognosis. Some persons less than 35 years old
with coma after head trauma, as well as an occasional patient with
coma after intracranial hemorrhage, may recover very slowly; thus,
what appears to be a PVS at one to three months after an event causing
coma may in rare cases evolve into a lesser degree of impairment
by six months. On the other hand, the chances of regaining independence
after being vegetative for three months are vanishingly small. Rare
exceptions are claimed, but some of these may have represented patients
who entered an unrecognized locked-in state shortly after reawakening
from a coma-causing injury. Ultimately, all have been severely disabled.
Guidelines
These rare examples notwithstanding, the data indicate that unawareness
for six months predicts nonrecovery or overwhelming disability with
a high degree of certainty regardless of the nature of the insult
to the brain. Therefore, a conservative criterion for the diagnosis
of PVS would be observed unawareness for at least 12 months although
cognitive recovery after six months is exceedingly rare in patients
over 50.
The risk of prognostic error from widespread use of the above
criterion is so small that a decision that incorporates it as
a prognostic conclusion seems fully justifiable. A physician's
determination that a person is unlikely to regain consciousness
is the usual prelude to deliberations about withdrawing or withholding
life support. Although the family may be the first to raise the
issue, until a physician has ventured an opinion about prognosis,
the matter of withholding treatment is not generally considered.
Once the question of withholding or withdrawing life support has
been raised, its legal and ethical dimensions must be considere.
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