A diagnosis of brain stem death is considered when:
- a person fails to respond to any outside stimulation
- the person is unconscious
- the person's heartbeat and breathing can only be maintained using a ventilator
- there is clear evidence that serious damage to the brain has occurred, and it cannot be cured
Ruling out other conditions
Before testing for brain stem death can begin, doctors must carry out a series of checks to make sure that the symptoms are not being caused by other factors. Possible factors include:
- an overdose of illegal drugs, tranquillisers, poisons or other chemical agents
- having an abnormally low body temperature (hypothermia - symptoms)
- having a condition that can affect the metabolism (the process that turns food into energy), such as diabetes (a long-term condition caused by too much glucose in the blood) or liver disease (when the liver is damaged, often through drinking excessive amounts of alcohol)
Once these factors have been ruled out, a number of tests are carried out to confirm the diagnosis. The diagnosis of brain stem death has to be made by two senior doctors. Neither of them can be involved with the hospital's transplant team.
The doctors will explain the tests to you, and will keep you informed about your loved one's condition at all times.
Tests
The doctors will run a series of tests. Both of them have to agree on the results for a diagnosis of brain death to be confirmed. The tests are carried out twice to minimise any chance of error.
The tests used to determine whether brain stem death has occurred are outlined below:
- a torch is shone into both eyes to see if they react to the light
- the cornea (transparent outer layer of the eye), which is normally very sensitive, is stroked with a tissue or piece of cotton wool
- pressure is applied to the forehead and the nose is pinched to see if there is any movement in response
- ice-cold water is squirted into each ear, which would normally cause the eyes to move
- a thin, plastic tube is place down the trachea (windpipe) to see if this provokes a gagging or coughing reflex
- the person is withdrawn from the ventilator for a short period of time to see if they make any attempt to breathe on their own
If a person fails to respond to all of these tests, a diagnosis of brain stem death is made.
Occasionally, a person’s limbs or their torso (the upper part of their body) may move, even after brain stem death has been diagnosed. These are spinal reflex movements, which means they are generated by the spinal cord and do not involve the brain at all. These movements will not affect the diagnosis of brain stem death.
