Brain stem death

Diagnosing brain stem death

There are a number of criteria for diagnosing brain stem death.

A patient:

• must be unconscious and fail to respond to outside stimulation
• must only be able to breathe by using a ventilator
• must show no brain stem reflexes – these reflexes include coughing, gagging, and pupils responding to light
• must show clear evidence that serious brain damage has occurred and can’t be reversed – this would usually be shown on a CT scan

Ruling out other conditions

Before testing for brain stem death, two senior doctors must carry out a series of checks.

This process makes sure that the signs of brain stem death aren’t being caused by other factors, like:

• an overdose of drugs, poisons or other chemical agents
• an abnormally low body temperature (hypothermia)
• low levels of sugar or salts in the patient’s blood

Once these factors have been ruled out, tests are carried out to confirm brain death. The diagnosis of brain death also has to be made by two senior doctors.

The doctors will explain the tests to you. You will be kept informed about your loved one’s condition at all times.

Testing for brain stem death

The two doctors will run a series of tests. They both 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:

• shining a torch into both eyes to see if the patient reacts to the light
• stroking the cornea (the transparent outer layer of the eye) with a tissue or piece of cotton wool to see if the eye reacts
• applying pressure to the forehead to see if the patient moves in response
• inserting ice-cold water into each ear, which would usually cause a person’s eyes to move
• inserting a thin, plastic tube down the patient’s trachea (windpipe) to see if they gag or cough
• disconnecting the person from the ventilator for a short period of time to see if they make any attempt to breathe on their own

Brain death will only be diagnosed if a person does not respond to all of these tests.

Occasionally, a person’s limbs or torso (the upper part of the body) may move after brain stem death has been diagnosed. These are spinal reflex movements generated by the spinal cord, and don’t involve the brain at all. They’ll not affect a diagnosis of brain stem death.

Once brain stem death is diagnosed, even though the patient’s heart is still beating, they are legally dead.

At this point the medical professionals will discuss next steps with a patient’s loved ones. This can include discussing potential organ donation, or other things that are important for end-of-life care for the patient.

Organ and tissue donation

After brain death has occurred, it may be possible for the person’s organs and tissue to be used for organ donation. This can often save or improve the lives of others.

Further information about organ and tissue donation

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