Issues Magazine

Brain Death Determination in the Adult

Source: 

Australian and New Zealand Intensive Care Society (http://tinyurl.com/mgho27z)

Whole brain death is required for the legal determination of death in Australia. If the condition causing coma and loss of all brain-stem function has affected only the brain-stem and there is still blood flow to the supratentorial part of the brain (the cerebral cortex), this does not meet the legislative requirements in Australia. This contrasts with some other countries where brain-stem death (even in the presence of cerebral blood flow) is the accepted standard.

In Australia brain death cannot be determined unless there is evidence of severe brain injury sufficient to cause death. Such injury is associated with an increase in the pressure inside the skull which cuts off the blood supply to the brain. Blood flow to the brain ceases and the entire brain, including the brainstem, dies. There is no recovery from brain death.

Before clinical testing for brain death can even begin other causes of deep coma such as drugs, high or low blood sugar levels and abnormal electrolyte levels must be ruled out. There must also be a minimum of 4 hours observation and mechanical ventilation, during which the patient is completely unresponsive to all stimuli (Glasgow Coma Score of 3), with pupils that don’t respond to bright light, no cough even when a suction catheter is put down the endotracheal tube into the lung and no breathing efforts of any kind, before clinical testing for brain death determination can be performed.

Brain death testing is carried out by two medical practitioners with specific experience and qualifications according to State and Territory laws. Two separate sets of tests are performed, with each doctor being responsible for performing one set of tests. The tests may be done consecutively but not simultaneously.

Clinical testing to determine that brain death has occurred requires that the following conditions apply at the time of the testing:

  • brain scans or other tests show sufficient brain pathology to cause death; and
  • body temperature is normal; and
  • blood pressure is normal and sufficient to not faint; and
  • sedative drugs and other drugs are not causing coma; and
  • significant electrolyte, metabolic or endocrine (hormone) disorders are absent; and
  • neuromuscular function – the transmission of signals from nerve to muscle – is intact; and
  • examination of brain stem reflexes is not prevented by, for example, severe injuries to the eyes or ears; and
  • it is possible to confirm the absence of any ability to breathe without blood oxygen levels falling too low.

And then:

  • absence of brain reflex responses to all stimuli including pain; and
  • absence of brain-stem reflexes – the basic reflexes that protect the body and maintain life; and
  • complete absence of any breathing efforts even when the patient is not connected to the mechanical ventilator for much longer that anyone would be able to hold their breath – breathing is a basic instinct that is essential for people to stay alive.

If for any reason clinical tests cannot be used to determine that brain death has occurred, for example because of severe injuries to the face and head affecting the eyes and ears, or the presence of sedative drugs commonly used in patients in intensive care, then brain death is determined by special X-rays of the head that demonstrate that there is no blood flow to the brain.