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Brain death

What is brain death?


The term “brain death” may be used to refer to an irreversible and complete loss of brain function (the death of the brain as an organ), but is more commonly used to describe the diagnosis of an individual declared dead according to neurological criteria.


Traditionally, the irreversible cessation of circulatory functions was understood as the point of death. When the circulatory system stops, the body begins to decompose. The body no longer processes nutrition and oxygen or maintains its temperature. This “cardiopulmonary death” is still the most common category of death, but today a patient with a beating heart and functioning circulatory system may be pronounced dead based on neurological criteria, that is, based on the loss of brain function.

Image by Natanael Melchor

The idea that brain failure is the same as death first gained traction in August 1968 when a committee from Harvard Medical School published a report in the Journal of the American Medical Association called “A Definition of Irreversible Coma.” The first sentence of their report stated, “Our primary purpose is to define irreversible coma as a new criterion for death.” 


The Harvard committee named two reasons for a new definition of death: 1) Medical advances in resuscitative and life-support measures allowed more and more patients to be brought back from the brink of death, but if these patients continued to live with significant brain damage, “The burden is great on patients who suffer permanent loss of intellect, on their families, on the hospitals, and on those in need of hospital beds already occupied by these comatose patients” and 2) “Obsolete criteria for the definition of death can lead to controversy in obtaining organs for transplantation.”


(The committee’s report was released in the months following the first human heart transplants. The transplants involved the removal of still-beating hearts from the bodies of brain-damaged donors. Even today, hearts and some other organs can only be transplanted from people still alive according to cardiopulmonary criteria.)


The committee gave guidelines on how brain death may be clinically diagnosed but did not argue that the death of a person’s brain is, in fact, equivalent to the death of the whole person. Rather, the committee’s reasons were that it was more societally convenient for the medical profession to treat brain death as equivalent to a person’s death. 


“We suggest that responsible medical opinion is ready to adopt new criteria for pronouncing death to have occurred in an individual sustaining irreversible coma as a result of permanent brain damage.”


Within two years of the Harvard committee’s proposal, states began to adopt the postulate that brain death was equivalent to whole body death. Today, most states legally recognize a diagnosis of brain death, or the cessation of all brain functions, as a person’s death. 


However, the tests for diagnosing brain death vary from state to state, hospital to hospital, and physician to physician. A patient may be dead according to one set of brain death criteria and alive according to another set of brain death criteria. 


Despite the definition of brain death being the irreversible cessation of ALL brain functions, physicians do not test for all brain functions before declaring brain death. 


The tests for brain death center around assessing the patient’s reflexes, which are controlled by the brain stem. Most tests involve shaking the patient’s head to see whether his eyes move, touching his eyeballs, and squirting ice water in his ears. Finally, if the patient shows no response to the physical stimuli, his ventilator is switched off to see if he tries to breathe as the carbon dioxide levels rise in his body. This last is called the apnea test. 


Because of the number of patients waiting for organ donations, federal law requires that hospitals that receive federal funds (practically every hospital) notify organ procurement organizations of every patient death and impending patient death. The organ procurement organization has time to come and assess what organs are usable, whether the patient is affirmatively an organ donor, and, if he is not, whether the patient’s family will allow his organs to be donated. If the patient designated himself as an organ donor on his driver’s license or has expressed an interest in organ donation, he is presumed to be an organ donor and his family cannot override that designation. If, however, he said he did not want to be an organ donor, legally his family may override his wishes and donate his organs. 


If he is diagnosed as brain dead, his treatment will continue only until his functioning organs are removed. After his organs are taken he will be dead according to cardiopulmonary standards, too. Most transplanted organs are retrieved from donors with beating hearts. Hearts themselves can only be taken while still beating.


Once someone is pronounced brain dead, physicians are no longer bound to feed him or follow his requested treatment plans. His instructions for prolonging his life or giving treatment are irrelevant for what is legally his corpse.


Since part of the definition of brain death is that recovery is impossible, no one ever recovers from brain death, but several people have recovered after being diagnosed as brain dead. If someone recovers after a diagnosis of brain death, the explanation is that the diagnosis was incorrect.

There are currently efforts underway to normalize organ donation after cardiac or circulatory death, which can only happen when circulatory death happens in a controlled environment. This type of organ donation is encouraged for patients who are on life support to facilitate their breathing or circulation. If a patient’s family members agree to discontinue life support and donate the patient’s organs, procurement specialists are on site to take organs the moment the heart stops.(1)


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