In order to be declared brain dead, a person needs to have no activity in either the brain or brain stem, at the base of the brain.
A 13-year-old girl in California continues to be on a ventilator after being declared brain-dead by doctors. Although a brain-dead person is not legally alive, how much of the body will keep on working with the help of technology, and for how long?
Jahi McMath of Oakland, Calif., was declared brain-dead last month after experiencing an extremely rare complication from tonsil surgery. Jahi's family members have fought to keep their daughter on a ventilator, but a judge has ordered that the machine be turned off next week.
A person is considered brain-dead when he or she no longer has any neurological activity in the brain or brain stem — meaning no electrical impulses are being sent between brain cells. Doctors perform a number of tests to determine whether someone is brain-dead, one of which checks whether the individual can initiate his or her own breath, a very primitive reflex carried out by the brain stem, said Dr. Diana Greene-Chandos, an assistant professor of neurological surgery and neurology at Ohio State University Wexner Medical Center. "It's the last thing to go," Greene-Chandos said. [10 Surprising Facts About the Brain]
In the United States and many other countries, a person is legally dead if he or she permanently loses all brain activity (brain death) or all breathing and circulatory functions. In Jahi's case, three doctors have concluded that she is brain-dead.
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