Brain death

The concept of brain death as defining death is largely accepted [1]. Most countries have published recommendations for the diagnosis of brain death but the diagnostic criteria differ from country to country [2]. Some rely on the death of the brainstem only [3] others require death of the whole brain including the brain stem [4]. However, the clinical assessments for brain death are very uniform and based on the loss of all brainstem reflexes and the demonstration of continuing cessation of respiration – ie apnea testing [5] - in a persistently comatose patient (see Table).

There should be an evident cause of coma and confounding factors (including hypothermia, drugs, electrolyte, and endocrine disturbances) should be excluded. A repeat evaluation in 6h is advised, but the time period is considered arbitrary [6].

Confirmatory neurophysiological tests such as electroencephalography, angiography, Doppler sonography, or scintigraphy or are only required when specific components of the clinical testing cannot be reliably evaluated and are recommended by a number of national professional societies to confirm the clinical diagnosis of brain death [7].

 

Table: Criteria for brain death as published by the American Academy of Neurology. [6]

  • Demonstration of coma
  • Evidence for the cause of coma
  • Absence of confounding factors, including hypothermia, drugs, electrolyte, and endorcrine disturbances
  • Absence of brainstem reflexes
  • Absent motor responses
  • Apnea
  • A repeat evaluation in 6h is advised, but the time period is considered arbitrary
  • Confirmatory laboratory tests are only required when specific components of the clinical testing cannot be reliably evaluated

Organ donation

Organ donation saves lives.

Defining death and organ harvesting are inextricably linked because of the “dead donor rule”. This rule requires patients to be declared dead before the removal of life-sustaining organs for transplantation. Consequently, it is considered unethical to kill patients for their organs no matter how ill they are or how much good for others can be accomplished by doing so. To avoid conflict, transplant-surgeons are excluded from performing brain death examinations.

Classically, organs are taken in patients who are declared brain death. Alternatively, the Pittsburgh protocol [8] for non-heart-beating donors also permits to harvest organs in hopelessly comatose patients.

 

References

1.         Laureys, S. (2005). Science and society: death, unconsciousness and the brain. Nat Rev Neurosci  6, 899-909.
2.         Haupt, W.F. and Rudolf, J. (1999). European brain death codes: a comparison of national guidelines. J Neurol  246, 432-437.
3.         Medical Royal Colleges and their Faculties in the United Kingdom (1976). Diagnosis of brain death. B.M.J.  2, 1187-1188.
4.         Medical Consultants on the Diagnosis of Death (1981). Guidelines for the determination of death. Report of the medical consultants on the diagnosis of death to the President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research,. JAMA  246, 2184-2186.
5.         Wijdicks, E.F. (2001). The diagnosis of brain death. N Engl J Med  344, 1215-1221.
6.         The Quality Standards Subcommittee of the American Academy of Neurology (1995). Practice parameters for determining brain death in adults (summary statement). Neurology  45, 1012-1014.
7.         Wijdicks, E.F. (2002). Brain death worldwide: accepted fact but no global consensus in diagnostic criteria. Neurology  58, 20-25.
8.         (1993). University of Pittsburgh Medical Center policy and procedure manual. Management of terminally ill patients who may become organ donors after death. Kennedy Inst Ethics J  3, A1-15.

Links

United Network for Organ Sharing

Eurotransplant