brain death

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Projection areas of the brain.

wet brain brain edema.


the cessation of all physical and chemical processes that invariably occurs in all living organisms. (See also dying.) There is at present no standardized diagnosis of clinical death or precise definition of human death. The most widely known and commonly accepted means of determining death evolved from several medical conferences held in the late 1960s for the purpose of defining irreversible coma or nonfunctioning brain as a new criterion for death. The indications of deep irreversible coma (or brain death) are (1) absolute unresponsiveness to externally applied stimuli; (2) cessation of movement and breathing, including no spontaneous breathing for three minutes after an artificial respirator has been turned off; and (3) complete absence of cephalic reflexes. The pupils of the eyes must be dilated and unresponsive to direct light.

Use of the electroencephalogram is also recommended as being of value in confirmation of irreversible coma or death. If there is a flat electroencephalographic reading at the time of apparent death and a second flat reading 24 hours later, then the patient may be declared dead.

There are two exceptions to the above criteria. These are in regard to patients exhibiting marked hypothermia (body temperature below 32.2°C), and those suffering from severe central nervous system depression as a result of drug overdose.

It is recognized that the above criteria are limited in that the notion of irreversibility is not readily agreed upon and may take on new meaning as medical technology advances. The criteria are especially helpful as complements to the traditional criteria of absence of heart beat and lack of spontaneous respiration as indications of death.

In 1981, a Presidential Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research strongly recommended that all of the United States recognize the cessation of brain function as a definition of death, even in cases in which life-support systems could maintain respiratory and circulatory functions by artificial means.
activation-induced cell death (AICD) recognition and deletion of T lymphocytes that have been activated and so induced to proliferate. T lymphocytes are activated when a foreign agent is perceived, and AICD thereby prevents them from overgrowth. It is particularly important for regulation of lymphocytes that recognize self antigens.
black death bubonic plague; see plague.
brain death (cerebral death) see brain death.
clinical death the absence of heart beat (no pulse can be felt) and cessation of breathing.
cot death (crib death) sudden infant death syndrome (SIDS).
programmed cell death the theory that particular cells are programmed to die at specific sites and at specific stages of development.

ce·re·bral death

a clinical syndrome characterized by the permanent loss of cerebral and brainstem function, manifested by absence of responsiveness to external stimuli, absence of cephalic reflexes, and apnea. An isoelectric electroencephalogram for at least 30 minutes in the absence of hypothermia and poisoning by central nervous system depressants supports the diagnosis.
Synonym(s): brain death

brain death


brain death

Etymology: AS, bragen + death
an irreversible form of unconsciousness characterized by a complete loss of brain function while the heart continues to beat. The legal definition of this condition varies from state to state. The usual clinical criteria for brain death include the absence of reflex activity, movements, and spontaneous respiration requiring mechanical ventilation or life support to continue any cardiac function. The pupils are dilated and fixed. Because hypothermia, anesthesia, poisoning, or drug intoxication may cause deep physiological depression that resembles brain death these parameters must be within normal limits prior to testing. Diagnosis of brain death may require evaluating and demonstrating that electrical activity of the brain is absent on two electroencephalograms performed 12 to 24 hours apart. Brain death can be confirmed with electroencephalograms showing a complete lack of electrical activity (a flat line) or vascular perfusion studies showing a lack of blood flow to the brain. Also called irreversible coma. Compare coma, sleep, stupor.
The irreversible cessation of all functions of the entire brain, including the brain stem

brain death

End of life The irreversible cessation of all functions of the entire brain, including the brainstem. See Appropriate period of observation, Attending physician, Corroborating physician, Harvard criteria, Multiorgan donation.
Harvard criteria for brain death
  • Unreceptivity and unresponsiveness
  • No movement or breathing
  • No reflexes
  • Flat electroencephalogram (confirmatory)
In addition, the following must be present
  • Body temperature ≥ to 32º C
  • Absence of CNS depressants

brain death

(brān deth)
Loss of brain function.

brain death

The absence of any signs of brain function. The state in which there are no reflex responses above the neck, there is no spontaneous breathing, and the ELECTROENCEPHALOGRAM shows no sign of electrical activity in the brain. This definition does not apply unless it can also be shown that a cause such as deep intoxication, or paralysing drugs, can be completely ruled out, and the effect of lowered body temperature (HYPOTHERMIA) eliminated.

ce·re·bral death

(ser'ĕ-brăl deth)
Clinical syndrome characterized by permanent loss of cerebral and brainstem function, manifested by absence of responsiveness to external stimuli, absence of cephalic reflexes, and apnea.
Synonym(s): brain death.

brain death,

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