What brain death means

... our reader Paul-Hermann M. wanted to know. We provide the facts and ask experts about the consequences of severe brain damage

Respiratory failure, lack of reflexes, and brain activity indicate possible brain death

© istock / Teka77

Brain death is the colloquial term for damage to the cerebrum, cerebellum and stem. It weighs so heavily that it can no longer regenerate. The cause is often a severe cardiovascular failure: The brain cells are then no longer adequately supplied with oxygen and die. Serious brain injuries, for example as a result of a motorcycle accident, can also lead to brain death.

All brain functions go out. The patient no longer breathes, the heart stops beating. Cardiac and circulatory functions can only be maintained through intensive medical measures.How is brain death reliably determined? Intensive care physician Professor Uwe Janssens, President of the German Interdisciplinary Association for Intensive and Emergency Medicine, summarizes the diagnostic steps:

Is brain function irretrievably lost?

© W & B / Astrid Zacharias


© W & B / Astrid Zacharias

Existing reflexes

Does the patient still swallow, does his pupil constrict, does he react to pain? Even in the deepest coma - an important indicator of brain death - a person still shows reflexes. They go out, however, if the brain damage is too severe.

© W & B / Astrid Zacharias

Independent breathing

The respiratory center no longer functions in the event of severe brain damage. In addition, doctors must rule out the possibility of severe poisoning, hypothermia or drug overdose, which can simulate brain death.

© W & B / Astrid Zacharias

Activity of nerve cells

Electroencephalography (EEG) measures the electrical activity of nerve cells in the brain. If a person is brain dead, no more activity can be detected. The EEG then shows the so-called zero line.

© W & B / Astrid Zacharias

Blood flow to the brain

The cessation of blood flow to the brain, for example as a result of massive brain swelling due to injury, can also be used to confirm the diagnosis of "brain death". It is measured by various methods.

© W & B / Astrid Zacharias

In the four-eyes principle

Two specialists, who will later not be involved in a possible transplant, diagnose the death of the brain. You must have several years of intensive medical experience with acute severe brain damage.


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The following studies answer this question in Germany

Professor Eckhard Nagel is a transplant specialist and ethics expert at the University of Bayreuth. We asked him:

Professor Nagel, what does brain death mean?

It is a point in the process of dying when human existence is extinguished. Body functions are only maintained by machines.

Why is it so elusive for many?

Our aesthetic perception of death is that of a pale, cold, rigid body. Man has usually died hours or days when we see his corpse; a perception to which we have become accustomed over millennia.

Could brain death be misdiagnosed?

Not if the regulations are followed. There is no known case in which a patient came back to life after a definite diagnosis.

Nevertheless, the diagnosis is fraught with fear.

Death unsettles and moves us. People used to be afraid of being buried alive. Coffins sometimes had an air duct upwards. Belief in the resurrection also gives the perspective that things will continue after death.

Sufficient time for a reliable diagnosis

In the case of acute severe brain damage, examinations at prescribed intervals are mandatory


Coma, respiratory failure and lack of reflexes are determined by the treating physicians. In addition, the activity of the nerve cells (EEG) and the blood flow in the brain can be measured.

After 12 hours

Is the patient still in a coma, lack of reflexes, is he breathing with assistance? In the event of direct damage to the brain, for example through an accident, irreversible brain death is now certain.

After 72 hours

In the event of indirect brain damage from respiratory or cardiovascular arrest, the clinical symptoms are checked again. Then brain death has certainly occurred here too.


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Saving life after death

If the patient has decided to donate organs during their lifetime, their cardiovascular function is artificially maintained even after the brain death diagnosis in order to supply the organs until they are removed. Further information is available on the Internet at www.dso.de.


Serious damage can irreversibly destroy the functioning of the brain. All conscious and unconscious processes are stopped. Communicating and thinking, moving, seeing, feeling and smelling are no longer possible.

If performed correctly, brain death diagnostics are a safe tool for determining death. Because the circulation is often maintained with machines, it is difficult for many relatives to accept death.