Irreversible cessation of the functions of the brain and brainstem
- Age, gender, genetics, and lifestyle are not significant factors
When a person does not respond to external stimuli because of brain damage, he or she is in a state of coma. In some cases, damage may affect the whole brain, including the brainstem. This part of the brain controls many of the body’s vital automatic functions, such as heart rate and breathing. If the brainstem is severely damaged, such as after a head injury, these vital functions may be affected; if this damage is irreversible, the person may be certified as brain dead.
A person who is brain dead is unable to respond to any stimuli and cannot breathe independently. Without a life-support machine (see Intensive therapy unit), death occurs within a few minutes and, even with life support, death occurs within a few days.
What might be done?
If doctors believe that brain death has occurred, a series of tests is carried out by two experienced medical consultants to confirm the diagnosis. These tests check the person’s response to stimuli and the functions that are controlled by the brainstem. They include testing the ability to breathe independently without a life-support machine.
A diagnosis of brain death is made only if doctors confirm that brain and brainstem functions have been lost, and that the cause has been identified but cannot be reversed, in spite of everything possible having been done.
Someone with brain death will not survive for more than a few days, even with care in an intensive therapy unit. Full medical support, including mechanical ventilation, will continue while relatives are given counselling. Doctors will discuss the situation fully with the family, and involve family members as much as possible in the decision of when to switch off the life-support machine.
Depending on the age and previous health of the person and the cause of death, relatives may be asked about their wishes regarding organ donation.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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