Brain death.

Brain death is a form of death that occurs when all brain activity stops. Although heart and respiratory function can be maintained through artificial means even after brain activity has stopped, brain death is a permanent and irreversible condition. In most cases, brain death is the result of some sort of severe trauma that prevents blood from flowing into the brain. When a person appears to be brain-dead, a doctor or other qualified medical professional must perform a series of tests to confirm the diagnosis. Once brain death is declared, the patient is legally considered dead. At that point, it is up to the patient's family to decide when to turn off life support devices. Often, the patient is kept on life support for a short time after brain death has been declared to give loved ones time to say their goodbyes and make the appropriate arrangements.