Brain Stem Death

Definition:

Brain Stem Death, also referred as Brain Death is an irreversible cessation of brain stem function whether induced by intra-cranial events or the result of extra-cranial phenomena, such as hypoxia, will produce this clinical state and therefore irreversible cessation of the integrative function of the brain stem equates with the death of the individual and allows the medical practitioner to diagnose death. Though, this is mainly assessed in intensive care settings, it is essential part of understanding for any acute physician.

Three things should be noted in this regard:

1. The irreversible loss of the capacity for consciousness does not by itself entail individual death. Patients in the vegetative state (VS) have also lost this capacity. The difference between them and patients who are declared dead by virtue of irreversible cessation of brain-stem function is that the latter cannot continue to breathe unaided without respiratory support, along with other life-sustaining biological interventions. This also means that even if the body of the deceased remains on respiratory support, the loss of integrated biological function will inevitably lead to deterioration and organ necrosis within a brief time.

2. The diagnosis of death because of cessation of brainstem function does not entail the cessation of all neurological activity in the brain. What does follow from such a diagnosis is that none of these potential activities indicates any form of consciousness associated with human life, particularly the ability to feel, to be aware of, or to do, anything. Where such residual activity exists, it will not do so for long due to the rapid breakdown of other bodily functions.

3. There may also be some residual reflex movement of the limbs after such a diagnosis. However, as this movement is independent of the brain and is controlled through the spinal cord, it is neither indicative of the ability to feel, be aware of, or to respond to, any stimulus, nor to sustain respiration or allow other bodily functions to continue.

Brain-stem death is not part of the VS, which has been defined as a clinical condition of unawareness of self and environment in which the patient breathes spontaneously, has a stable circulation, and shows cycles of eye closure and opening which may simulate sleep and waking.

The current position in law is that there is no statutory definition of death in the United Kingdom. Subsequent to the proposal of the ‘brain death criteria’ by the Conference of Medical Royal Colleges in 1976, the courts in England and Northern Ireland have adopted these criteria as part of the law for the diagnosis of death. There is no reason to believe that courts in other parts of the United Kingdom would not follow this approach.

Conditions necessary for the diagnosis and confirmation of the Death:

The following conditions must be fulfilled to allow the diagnosis of death following irreversible cessation of brainstem function to be undertaken. See Fig 2

1. Aetiology of irreversible brain damage should be known.
2. Exclusion of potentially reversible causes of coma.

The patient is deeply comatose, unresponsive and apnoeic, with his/her lungs being artificially ventilated.

• There should be no evidence that this state is due to depressants drugs.
• Primary hypothermia as the cause of unconsciousness must have been excluded.
• Potentially reversible circulatory, metabolic and endocrine disturbances must have been excluded as the cause of the continuation of unconsciousness.

Exclusion of potentially reversible causes of apnoea.

Fig 2: Diagnostic & Management Algorithm to Diagnose Death