Definition of Brain death

Brain death is an irreversible cessation of all functions of the brain and in most countries brain dead patients are declared dead medically and legally.

The brain dead is unable to breathe and must therefore lie in a respirator, but regardless the heart will usually stop after a few days. In rare cases, however, the heart continues to beat in 1-2 weeks. Without respiratory assistance the heart would normally stop after 5-10 minutes due to lack of oxygen in the heart muscle. Respiratory assistance thus prolongs the time during which the body's other organs can function gaining time to remove organs for transplantation depending on legislation, next of kin approval or the patients prior organ donation consent.

There is a particular set of conditions that must be met for a person to be declared brain dead. The organ transplantation possibilities and transplantation regulation vary from country to country. Normally guidelines will have been laid down by the National Board of Health concerning legal death criteria and transplantation criteria’s.

Typically two different doctors will each study the brain dead person with at least an hour apart. One doctor should be the one who has dealt with the person, and the second being an expert in the field, for example a specialist in neurosurgery, neurology and clinical neurophysiology.

Necessary conditions:

The person must be in a coma condition where breathing has stopped, so that respiratory therapy is needed. There must be a known cause for the brain activity cessation. This cause must be structural damage that cannot be treated and which is fatal.

Necessary exclusions:

It must be ruled out that the person is unconscious due to: poisoning, anesthesia, paralysis, disturbance in metabolism or hormones, low body temperature (below 35 degrees centigrade) or low blood pressure.

Clinical examination:

A very thorough neurological examination is performed covering the following: Pupil light-reflecting, cornea reflex, eyes response to passive movement of the head, reaction to pain stimulation, throat and cough reflex. Moreover, a so called apnoea test is performed to check that there is no longer spontaneous (automatic) breathing.

Causes of brain death

Brain death is often caused by a hard blow to the head resulting in irreversible damage to the brain typically resulting from traffic accidents, falling from height or violence. Such physical impact on the brain results in increased pressure inside the skull (the brain). When this increased pressure exceeds the person’s blood pressure the normal flow of blood to the brain is obstructed starving the brain cells of oxygen and without oxygen the brain cells die.

Brain death may also stem from large brain tumors, stroke by blood clot or haemorrhage or severe disturbance in the brains metabolism as all these conditions also lead to increased pressure in the brain with the same result.     

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