Brain death is widely accepted by doctors and lawyers as the criterion for death, despite the viability of other organs. Brain death occurs when the brain no longer functions and has no possibility of functioning again. The problem now becomes practical. How do we know when a person (for example, someone in a coma) is considered brain dead? There is general agreement that the criteria listed below, if met, denote brain death.
1) The nature and duration of the coma must be known.
a. Known structural damage to brain or irreversible
systemic metabolic disease.
b. No chance of drug intoxication, especially from
paralyzing or sedative drugs.
c. No sign of brain function for 6 h in cases of known
structural cause and when no drug or alcohol is
involved; otherwise, 12–24 h without signs of brain
function plus a negative drug screen.
2) Cerebral and brainstem function are absent.
a. No response to painful stimuli administered above the
b. Pupils unresponsive to light.
c. No eye movement in response to ice-water stimulation
of the vestibular reflex.
d. Apnea (no spontaneous breathing) for 10 min.
e. Systemic circulation may be intact.
f. Purely spinal reflexes may be retained.
3) Supplementary (optional) criteria.
a. Flat EEG (wave amplitudes less than 2 microvolts).
b. Responses absent in vital brainstem structures.
c. Greatly reduced cerebral circulation.