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A person dies when brain function ceases, the heart stops beating, and breathing and blood circulation cease. Because life-support techniques have become so advanced, it is possible that even in the face of fatal injury or unrecoverable illness, the heart can be kept beating with medication and respiration (breathing) can be artificially performed with a ventilator. The concept of brain death developed in response to these advanced medical techniques that can maintain some bodily functions. Brain death, as understood in US law and medical practice, occurs when there is no function of the entire brain. The brainstem is the area of the brain that controls breathing and circulation and therefore controls essential life functions. When the brain, including the brainstem, has ceased to function, the individual is truly dead by medical and legal standards. Thus, brain death is real death. The May 14, 2008, issue of JAMA includes an article about ethical questions sometimes raised in cases of brain death.
Clinical criteria for brain death
No response to any stimulus—no movement, withdrawal, grimace, or blinking
No breathing efforts when taken off the ventilator (the apnea test)
Pupils dilated and not responsive to light
No gag reflex, no corneal reflex (blinking when the surface of the eye is touched), and absence of other specific reflexes
Computed tomography (CT) scans of the brain may show abnormalities such as bleeding (hemorrhage), massive stroke, brain injury, or severe brain swelling (edema).
Electroencephalography (EEG) records electrical brain activity. If brain death is present, the EEG will show no activity.
Cerebral radionuclide injection shows no uptake of the radioactive material in the brain when a person is brain dead.
These tests may be performed to confirm brain death. They may be used along with the examination-based clinical criteria to show irreversible loss of brain and brainstem function. Not all tests need to be used to declare brain death.
Brain death and organ transplantation
Some organs (such as the heart) can only be transplanted if they are harvested from a dead person whose respiration and circulation are artificially maintained. Organ harvest takes place only after declaration of brain death. The dead individual's organs are maintained on life support for organ donation purposes only. The organ donation team is not involved until the patient is declared brain dead, and staff involved in organ donation or transplantation do not declare brain death.
For more information
National Institute of Neurological Disorders and Stroke
American Academy of Neurology
United Network for Organ Sharing
To find this and previous JAMA Patient Pages, go to the Patient Page Index on JAMA's Web site at http://www.jama.com. Many are available in English, Spanish, and French. A Patient Page on traumatic brain injury was published in the June 11, 2003, issue; one on head injury was published in the September 28, 2005, issue; and one on cardiac arrest was published in the January 4, 2006, issue.
Sources: National Institute of Neurological Disorders and Stroke, Coma Recovery Association, United Network for Organ Sharing, American Academy of Neurology
The JAMA Patient Page is a public service of JAMA. The information and recommendations appearing on this page are appropriate in most instances, but they are not a substitute for medical diagnosis. For specific information concerning your personal medical condition, JAMA suggests that you consult your physician. This page may be photocopied noncommercially by physicians and other health care professionals to share with patients. To purchase bulk reprints, call 203/259-8724.
TOPIC: BRAIN FUNCTION
Torpy JM, Kincaid JL, Glass RM. Brain Death. JAMA. 2008;299(18):2232. doi:10.1001/jama.299.18.2232
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