The definition and determination of brain death

Abstract

In most countries, brain death is defined as the irreversible and complete loss of (clinically ascertainable) function of the entire brain, including the brain stem. It is characterized by an irreversible loss of the capacity for consciousness, combined with loss of motor responses to painful stimuli, irreversible loss of brain stem reflexes and loss of the capacity to breathe. The diagnosis can be made clinically based on at least two examinations separated by a time interval, which depends on the cause of the underlying brain damage, the patient’s age and national conventions. Ancillary tests can confirm and speed the diagnosis of irreversible loss of brain function. Conventional angiography is the most sensitive technique, but relatively expensive, and because of potential side-effects not allowed for diagnosis in all countries. Electroencephalography and transcranial Doppler ultrasonography are alternative methods. Other techniques, for example evoked potentials, radionuclide techniques and magnetic resonance studies, are less valuable or need to be validated.