brain death

Brain death: description

For the first time in the second half of the twentieth century, physicians were confronted with being able to keep deeply-conscious, non-respiratory patients alive with machine and drug support. In the late 1950s, the first brain death definition was published. Only later was the organ donation option for brain dead.

The brain death concept is widespread almost worldwide. According to the Federal Center for Health Education (BZgA) occurs in one per cent of the approximately 400,000 dying in German hospitals a brain death per year before the cardiac arrest on. In Germany, statistically speaking, only every second brain death diagnosis is related to a planned organ or tissue donation.

How is the brain death defined?

The concept of brain death is often confusing and controversial, making it a subject of concern for many people. An American study showed that only 28 percent of enlightened brain stem volunteers could give a proper brain death definition. Therefore, the first problems arise with the question “what is brain death”.

In the details, the definitions differ internationally. However, the brain death definition always states that there is an irreversible brain function failure. At the same time, however, the spinal cord, even part of the central nervous system, may still function (restricted). The brain-dead person has a measurable pulse and blood pressure in the intensive care unit. So the body is still able to balance various bodily functions. However, this is only possible with intensive, mechanical support.

The decisive factor is that a brain-dead person can not breathe spontaneously so that the heart and circulation come to a standstill without mechanical ventilation. The German Ethics Council agreed that brain death is a sufficient condition for organ removal. However, a minority of the German Ethics Council sees brain death as not a “sufficient condition” for the death of a human being.

Brain death: symptoms

If a person is brain dead, they can not breathe on their own. Evidence of brain death is a lack of response to pain (no grimacing), no respiratory drive and the loss of brain stem reflexes. These reflexes are mediated by the brain stem, an important part of the brain. These include the strangling and coughing reflexes. Even the loss of eye reflexes can be an indication of brain death.

Most of the patients have low blood pressure and need circulation-supporting medications. At the same time, however, functions of other organs – apart from the brain – are preserved. Brain-dead people can drop, urinate, or even sweat. The body can thus maintain the internal balance (homeostasis) with the help of intensive care. Also, motor reactions, which are usually mediated through the spinal cord, can occur. This includes the so-called Lazarus sign. These are reflex reactions mostly from the arms or legs. Also convulsions of the facial muscles do not exclude a brain death basically. Such signs can be misinterpreted as signs of life and lead to an additional psychological burden on relatives.

Brain death: causes and risk factors

Ultimately, an oxygen deficiency of the brain is always the cause of brain death. Already an interruption of the oxygen supply of a few minutes can lead to a failure of the brain, the parent control of the human body.

In more than half of all cases, cerebral hemorrhage is the cause of brain death. Cerebral haemorrhages are usually the result of long-standing hypertension or a previously damaged blood vessel. Because the bony skull can not expand, the pressure on the brain increases due to the bleeding, so that the blood circulation in the brain-supplying vessels comes to a standstill.

The second most common cause is so-called ischemic-hypoxic brain damage, which is due to an oxygen deficiency of the brain, for example, due to a cardiovascular arrest caused. Only in third place of the brain death causes are accidents with craniocerebral injuries. Other causes include brain infarcts, tumors, brain inflammation and the appearance of a hydrocephalus (hydrocephalus).

Brain death: examinations and diagnosis

In Germany, brain death diagnostics are regulated in detail by the German Medical Association in accordance with the Transplantation Act (TPG). Most recently, the relevant directive in Germany was revised in March 2015. Precise and strict rules are intended to reduce uncertainties among medical staff, but above all fears and worries of relatives.

Brain death diagnostics must follow a well-regulated procedure. If the regulations are followed exactly, the brain death diagnosis is considered safe. The purpose of the detailed investigation is to establish the irreversible failure of the functions of most of the brain, especially the cerebrum, cerebellum and brainstem. The guideline of the German Medical Association uses the term “irreversible brain function failure” instead of “brain death”.

Two qualified doctors must independently detect brain death. Brain death diagnostics should only be performed by experienced and highly qualified doctors (intensive care, anesthetics, neurology or neurosurgery). At least one of the physicians should be a neurologist or neurosurgeon with many years of experience in the field of intensive care and brain death diagnostics.

The two doctors are not allowed to be involved in any organ donation that may follow, nor to accept instructions from the doctors involved.

The process of brain death detection is precisely regulated by a protocol and is done in three steps:

1. Are there any prerequisites for irreversible brain function failure?

First of all, it has to be determined whether there is enough brain damage at all. On the one hand, a distinction is made as to whether the brain is affected directly or only as the result of other damage (for example cardiac arrest). In addition, it examines where the damage is located in the brain. Roughly subdivided so-called supra- and infratentorial brain damage.

About the cerebellum is a connective tissue membrane, the “cerebellum tent” or Tentorium cerebelli. Supratentorial damage is above this membrane, infratentorial damage underneath. This subdivision is important for the further diagnostic procedure.

Helpful for this is a computed tomography (CT) of the brain. This imaging exam can detect massive damage to the brain. However, shortly after resuscitation or immediately after acute damage, the CT image may still appear normal. It must also be documented when this disease began or when the causative accident took place.

Even before the detailed brain death diagnosis can be initiated, other causes for the condition of the patient must be excluded. Other possible causes include poisoning, including medication or drugs, hypothermia or even shock. If necessary, the pain and / or anesthetic medication must be discontinued (for a sufficient amount of time).

2. Determination of the clinical symptoms as a brain death criterion

In the second step of brain death diagnostics, the clinical symptoms are checked according to the brain death protocol:

1. Condition of unconsciousness (coma): The patient must be addressed loud and clear. For this purpose, intense and repeated painful stimuli must be set. A comatose state exists if all reactions are followed by no reaction, especially no eye opening.
2. Steady rigidity of both medium to maximum wide pupils (without spreading medication)
3. Absence of the oculo-cephalic or vestibulo-ocular reflex: A lateral head rotation is used to check whether the eyes can fix a point against the rotational movement. This is also called doll’s head phenomenon. Alternatively, you can
4. an ear canal are rinsed with cold water, which would lead to an eye movement with preserved reflex. If the fixation is no longer possible or if an ear canal flush does not cause any reaction, the reflexes are considered to have failed.
5. Failure of the corneal reflex in both eyes: In healthy people, a touch of the cornea (clear skin in front of the pupil) leads to an immediate eyelid closure.
6. Absence of any pain reactions in the facial nerves (trigeminal nerve) and other regions.
7. No cough and gag reflex (pharyngeal / tracheal reflex)
8. Complete failure of independent breathing: The mechanical ventilation is interrupted for a short time. This test examines whether and how much the carbon dioxide level increases as a sign of lack of respiration in the blood.

3. Determination of irreversibility

The third stage of brain death diagnostics is the finding that this condition can not change. Experienced physicians choose the right tool to determine the irreversibility of brain death, depending on the case scenario. All methods have advantages and disadvantages with regard to their diagnostic value. In particular, in the infratentorial brain damage described above, certain conditions must be considered.

In most cases, either a defined observation time of 12 or 72 hours is awaited before a second horn death diagnosis and / or apparatus examinations are carried out. These possible investigations include:

• Electroencephalogram over 30 minutes without rashes from the zero line (isoelectric, repeated)
• Evoked potentials: no electrically measurable response to different stimuli (Seeing (VEP), Listening (AEP), Touching (SEP).
• Determination of blood circulation arrest in the brain with CT angiography, perfusion scintigraphy or Doppler ultrasound.

After completion of brain death diagnostics

If the patient is declared brain-dead and is eligible for organ donation, a message will be sent to the German Foundation for Organ Donation (DSO) as the coordinating organization. An organ donation must be expressly approved in Germany, a fundamental requirement is brain death. Organ donation is a difficult but important issue that relatives are often unable to cope with in this acute situation, and it is important to find out the will of the brain dead.

Children have special regulations

In children up to the second year of life, especially premature babies, special rules for the detection of brain death apply. The investigators must have accurate knowledge of maturity and age-related differences. For example, healthy newborns may have decreased brain activity. Accordingly, the protocol is also adapted.

Brain death: treatment

According to the current state of medical research, apart from the intensive medical preservation of crucial bodily functions and the circulation, no treatment of brain death is possible.

Brain death: disease course and prognosis

According to current knowledge, a recovery from the detected brain death is not possible. Reports on people who have awakened after brain death diagnosis, have so far been due to an inappropriate diagnosis. It was extremely rare for a pregnant woman to carry a child while maintaining intensive care. Even with artificial respiration, however, a continuous degradation of the dead brain substance begins. After about a week, the brain has largely resolved.

Following the discovery of the death of a potential organ donor, organs may be withdrawn subject to approval under strict regulations of the Transplantation Act (TPG). When the decision to donate organs has been made, the machine and drug support of the circulation is maintained until organ removal. Otherwise, after (brain) death, all (intensive) medical measures will be discontinued.

The timing of the definitive brain deathConfirmation is valid in Germany as death.