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What Is Brain Death?

Brain death is a rare event that occurs in one out of every 200 hospital deaths. It means that the brain is no longer working and never will again. When brain death is declared, it means the person has died.

What is Brain Death?

Brain death results from swelling in the brain; blood flow in the brain ceases and without blood to oxygenate the cells, the tissue dies. Once brain tissue dies, there is nothing that can be done to heal it. At this point, no brain function exists. Brain death is irreversible. Brain death is death.

Testing for Brain Death

Brain death is a rare event that occurs in one out of every 200 hospital deaths (CDC study, 1986). The diagnosis for brain death is very conservative and is only made when there is no doubt in the findings. A number of tests are performed by physicians to confirm: the patient has no response to verbal or visual command, the patient is flaccid; pupils are unreactive and fixed; has no oculocephalic, gag, oculovestibular or corneal reflexes; and there is no spontaneous respiration. Even after confirmation of these tests, many physicians request additional, tests before pronouncing brain death. These commonly include the electroencephalogram (EEG) and the cerebral blood flow (CBF) study.

The EEG measures brain voltage in microvolts. It is so sensitive that the static electricity in a person’s clothes will give a squiggle on the EEG (a false positive). All positive responses suggest brain function. The patient in the deepest coma will show some EEG electroactivity, while the brain-dead patient will not.

The cerebral blood flow (CBF) study involves the injection of a mild radioactive isotope into the blood stream. By placing a radioactivity counter over the head, one can measure the amount of blood flow into the brain. If there is no blood flow to the brain, the brain is dead. A negative cerebral flow study is indisputable evidence of a dead brain. 

Once the diagnosis of brain death is made, an individual is pronounced legally dead. Only then can organ donation become a possibility. 

Donation After Brain Death

Families of a brain-dead patient must, by federal regulations, be provided the option of organ donation. If the family declines donation, the mechanical ventilator, medications and fluids are discontinued, after which the heart stops. If the family says yes to donation, the regional organ procurement organization (LifeSource in MN, ND, SD) is involved. The donor’s body is kept functioning by artificial means, such as a ventilator support until the recovery of organs and tissue for life-saving transplant.  

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