Brain Death

Essentials

• Brain death denotes a state where all cerebrovascular circulation and brain function has permanently ceased.
• The diagnostic criteria, and the guidelines and protocols regarding the confirmation of brain death may vary from country to country. This article is based on the protocol applied in Finland.
• In the case of brain death, spontaneous breathing ceases.
  • Unless breathing is articially maintained, also cardiac arrest eventually occurs.
  • A person can be pronounced dead while the heart is still beating when permanent loss of brain function has been established by clinical investigations.
• In Finland, a patient is regarded dead when brain death is established, and intensive care should not be continued for other reasons than making organ donation possible. Find out about local definitions of death and brain death.
• Spinal and circulatory reflexes may still occur even after a patient has been pronounced brain dead.
  • The occurrence of these reflexes does not conflict with brain death diagnosis, and surgery to remove organs should not be delayed because of it.

Prerequisites for establishing brain death

• The cause behind the cessation of cerebrovascular circulation must be known (CT or MRI).
• A poisoning or other drug effect must be excluded.
  • A sufficient time (at least 4 times the half-life of the drug) must pass after the administration of anaesthetics, analgesics and muscle relaxants before clinical tests to establish brain death can be performed.
• Global ischaemia (cardiac arrest) must not have occurred within a period of 24 hours.
• If the patient is hypothermic (seeResuscitation in Accidental Hypothermia) at the time of admission to the hospital or if he/she has been treated with therapeutic hypothermia (e.g. because of cardiac arrest or brain injury), the patient's core temperature must be raised above 35 °C before investigations.
• A metabolic cause must be excluded.

Time of establishing diagnosis

• The investigations should be performed as soon as possible after the aforementioned prerequisites are met.
• According to the Finnish legislation, a clinical neurological examination and an apnoea test, each performed once according to the legal requirements, are sufficient for making the diagnosis of brain death.
• If the neurological examination or apnoea test cannot be carried out according to the legal requirements, the cessation of cerebrovascular circulation must be established by cerebrovascular angiography.
  • Digital subtraction angiography (DSA) has earlier been the standard investigation, but the use of CT angiography is increasing.Computed Tomography (CT) Angiography for Confirmation of the Clinical Diagnosis of Brain Death.

Physicians establishing brain death diagnosis

• Brain death should be established by a physician who has adequate experience and training for the task.
• In most cases, the death is established by two physicians
  • Neurological examination: neurologist, neurosurgeon or paediatric neurologist
  • Apnoea test: anaesthesiologist or intensive care specialist
• A physician involved in organ donation (a person who decides which organs are to be removed and to whom they are transplanted) must not establish brain death diagnosis or participate in the treatment of a potential donor.

Neurological examination

• Response to pain is tested by applying sufficient pressure on the supraorbital nerve on both left and right sides of the head.
  • The examination may continue only if no reaction to pain is acquired.
  • The painful stimuli must not elicit any changes in the heart rate or blood pressure.
• The absence of muscle tone must be verified.
• The functioning of the cranial nerves is tested systematically.
• There must be no response to pharyngeal, tracheal or pulmonary stimulation (e.g. by moving the endotracheal tube or during suctioning)
• Pressure/massage of the carotid sinus or an eyeball does not produce bradycardia.
• The pupils do not react to light, cornear reflex is absent and the eye lids do not close by themselves.
• The oculocephalic reflex is absent, i.e. no eye movement towards the opposite direction in response to a fast turning of the head or during neck extension and flexion.
• The vestibulo-ocular reflex is absent
  • Before the examination the tympanic membranes should be examined for being intact.
  • Following an ample injection (50-100 ml) of ice-cold water into each external auditory canal, no eye movements must occur during a few minutes' monitoring.
• The method of the neurological examination is documented and signed in the patient record.

Apnoea test

• Apnoea test is carried out after the neurological examination, provided that the neurological criteria are fulfilled, in the manner described in table T1.
• If apnoea test cannot be carried out, the cessation of cerebral circulation can be established by cerebrovascular angiography.
• The method of apnoea test is documented and signed in the patient record.
• The time when the cessation of spontaneous breathing was established is regarded as the time of death.
• If the apnoea test cannot be carried out and the cessation of circulation is established by angiography, the ending of the angiography is regarded as the time of death.

Documentation

• See local instructions as well as legal and other requirements about appropriate documentation.
• Documentation may include provision of e.g. the following information
  • How and by whom was the deceased person's position (when he/she was alive) on organ donation found out?
  • What was the deceased person's position on donation of organs and cells?
  • A report on the methodology of the neurological examination and apnoea test, as well as information on the persons carrying these out
  • Relevant diagnostic codes (brain death, underlying disease)