Diagnosis

There are a number of criteria fordiagnosing brain stem death.

For a diagnosis of brain stem death to be made:

• aperson must be unconscious and fail to respond to outside stimulation
• aperson's heartbeat and breathing can only be maintained using a ventilator
• there must be clear evidence that serious brain damage has occurred and it can't be cured

Ruling out other conditions

Before testing for brain stem death can begin, doctors must carry out a series of checks to ensure that the symptoms aren't being caused by other factors, such as:

• an overdose of illegal drugs, tranquillisers, poisons or other chemical agents
• an abnormally low body temperature (hypothermia)
• severe under-activity of the thyroid gland

Once these factors have been ruled out, tests are carried out to confirm brain death. The diagnosis of brain 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 they'll keep you informed about your loved one's condition at all times.

Tests

The doctors will run a series of tests. Both doctors 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 usually very sensitive, is stroked with a tissue or piece of cotton wool to see if the eyereacts.
• Pressure is applied to the forehead and the nose is pinched to see if there's any movement in response.
• Ice-cold water is inserted into each ear, which would usually cause the eyes to move.
• A thin, plastic tube is placed down the trachea (windpipe) to see if itprovokes gagging or coughing.
• The person is disconnected from the ventilator for a short period of time to see if they make any attempt to breathe on their own.

Brain death will bediagnosedif a person fails to respond to all of these tests.

Occasionally, a persons limbs or torso (the upper part of the body) may move, even after brain stem death has been diagnosed.

These spinal reflex movements are generated by the spinal cord and don't involve the brain at all. Therefore, they won't affect the diagnosis of brain death.

Brain stem

The brain stem is the lower part of the brain that is connected to the spinal cord and is responsible for regulating most of the automatic functions of the body that are essential for life, such as breathing.

Liver

The liver is the largest organ in the body. Its main jobs are to secrete bile (to help digestion), detoxify the blood and turn food into energy.

Spinal cord

The spinal cord is a column of nervous tissue located in the spinal column. It sends messages between the brain and the rest of the body.