Overview
Brain death describes a permanent and irreversible loss of brain function which includes the loss of autonomic activity to sustain life (such as breathing). A person who is brain dead is legally confirmed as dead and there is no chance of recovery as their body cannot survive without artificial life support.
It is important to note that an irreversible loss of consciousness does not mean death, this may apply to patients in a persistent vegetative state. These patients still have some autonomic activity to sustain life.
Assessment
Criteria for brainstem death testing
Full and thorough attempts should be made to rule out reversible causes such as hypothermia, metabolic and biochemical abnormalities, and sedation. Furthermore, there must be clear evidence that serious brain damage has occurred that cannot be cured.
Testing
Testing should be undertaken by at least 2 medical professionals that are competent in conducting and interpreting brain death testing and have more than 5 years of post-graduate experience. One of the must be a consultant and neither can be a member of the transplant team.
- Testing for brainstem reflexes:
- CN II – loss of pupillary reflex when light is shone into the eyes
- CN V – loss of corneal reflex
- CN VIII – loss of oculovestibular reflex (Caloric test)
- Involves irrigating ice water into the ear. The eyes do not move to the irrigated side
- CN IX – no gag reflex after bilateral stimulation of the posterior pharyngeal membranes
- CN X – loss of cough reflex after bronchial stimulation (e.g. suction catheter placed down the trachea to the carina)
- Apnoea test:
- The last brainstem test. It is not performed if the previous tests confirm the presence of brainstem reflexes
- Disconnection from a ventilator (usually 5 minutes) leads to an elevation of pCO2 to at least 6.0 kPa (or 6.5 kPa in those with chronic hypercapnia). Oxygen is given before and after to reduce hypoxia and its complications.
Limb and torso movements may remain. This is controlled independently of the brain and mediated through the spinal cord. It does not suggest an ability to feel, be aware of, or respond to any stimulus, nor to sustain autonomic functions to sustain life.
