Historical Background

Evolution of a Concept

For many centuries death was determined based on cessation of cardiorespiratory function. Advances in medical technology have allowed for cardiac and respiratory functions to be maintained artificially even in the presence of irreversible loss of brain function. As early as 1959, published reports described clinical

Organ Procurement and Preservation, edited by Goran B. Klintmalm and Marlon F. Levy. © 1999 Landes Bioscience

■ conditions similar to what we currently view as brain death.1,2 Mollaret and Goulon1 coined the term "coma dépassé" (state beyond coma) to describe a neurological state associated with deficits beyond what has been previously described as coma. Such patients were unresponsive, had no brainstem reflexes and showed progressive hemodynamic collapse. The authors reflected on the prognosis of such a condition but did not equate it to death nor did they recommend withdrawal of ventilatory support. During the same year, a second group2 described "death of the central nervous system". These patients also lacked brainstem reflexes, were ap-neic in spite of hypercapnea and had an electrically silent electroencephalogram (EEG) with scalp and deep thalamic electrodes. The authors concluded that in such conditions recovery was not possible and that respiratory support was to be discontinued.

These early reports were followed by several studies that attempted to define clinical criteria for brain death and methods for diagnosis. As investigators moved toward more objective evidence and supportive studies, the concept of brain death became somewhat blurred with an evolution toward a more clinical approach in determining brain death and efforts to accept brain death as patient death.

In 1968, the Ad Hoc Committee of the Harvard Medical School to Examine the Definition of Brain death published its report, "A Definition of Irreversible Coma".1 Its primary purpose was to define irreversible coma as a new criterion for death. The definition included the criteria of coma, absence of spontaneous respirations and movements, unresponsiveness, dilated pupils, loss of cephalic and deep tendon reflexes and absence of postural responses. A flat or isoelectric EEG was considered of "great confirmatory value". Testing was to be repeated at least 24 hours later with no change. The final diagnosis of brain death was dependent on the exclusion of hypothermia (temperature below 32.2°C) and presence of central nervous system depressants (e.g., barbiturates). The authors failed to describe what would happen if mechanical ventilation was discontinued.

In 1971, Mohandas and Chou1 formulated criteria for brain death based on clinical grounds. The authors did not feel an EEG was mandatory and repeat examinations could be performed at 12 hours. However, patients should have had irreparable brain lesions "with presently available means". The proposed criteria emphasized the clinical diagnosis of brain death and set the foundation for more modern criteria for determining brain death which included: 1) defining a clear irreparable etiology for brain death, 2) emphasis on brainstem death with loss of brainstem reflexes, 3) questioning the value of an EEG in that setting.

In 1976, the Conference of Royal Colleges and Faculties of the United Kingdom endorsed a document outlining the diagnostic criteria for determining brain death.1 The criteria were also based purely on clinical grounds with strong emphasis on brainstem death. Included was a detailed outline of preconditions and cautionary notes while considering brain death. This became known as the "UK code" and was discussed in much greater detail by Pallis.2 The author emphasized the conceptual evolution from classical death to brain death as an initial step and subsequently from total brain death to brain stem death.

In 1981, the President's Commission for the Study of Ethical Problems in Medicine published its report "Guidelines for the Determination of Death"1 (Table 1.1). The Commission stated that "an individual with irreversible cessation of the entire brain, including the brain stem, is dead." The report was similar in many ways to the UK code and also outlined complicating conditions that may affect the accuracy and reliability of brain death diagnosis. The emphasis was on cessation of cerebral and brain stem functions, establishment of irreversibility and evaluation for complicating conditions. Confirmatory studies, such as EEG or cerebral blood-flow, were suggested when criteria were not met as outlined. These criteria subsequently became the text for brain death legislation in all 50 states.

Legislative Background

Acceptance of brain death as clinical death was dependent on the integration of both medical and legal criteria. "Death" has long been accepted as meaning "cessation of respiratory and cardiac functions". Yet, while such functions can be replaced by machines and to some extent pharmacologic agents, those of the brain cannot. Therefore, the evolution into brain death as an acceptable diagnosis of death was a natural one. Although earlier reports1 have described this condition with its eventual outcome, it was not until 1971 in Finland that brain death was first legally accepted as death.1

In the United States, legislative activity in support of organ donation and brain death diagnosis started at the state level. The Uniform Anatomical Gift Act (UAGA) of 1968 established the legality of anatomical gifts after death, the organ donor card and also prohibited the sale of organs. By 1972, the UAGA had been adopted in all 50 states. However, without brain death laws, removal of organs was possible

Table 1.1. President's commission criteria for brain death

1.

Absence of:

a) Cerebral functions: deep coma

b) Brain stem function: pupillary, corneal, oculovestibular, gag, cough, respiratory

(apnea) reflexes

2.

Irreversibility:

a) Cause of coma is established

b) Possibility of recovery of any brain function is excluded

c) Findings confirmed on a second exam after an appropriate period of

observation

3.

Complicating conditions:

a) Drug and metabolic intoxication

b) Hypothermia: below 32.2oC core temperature

c) Children: younger than 5 years require longer periods of observation and

supportive studies

d) Shock

4.

Confirmatory studies:

Not required. EEG or blood-flow study may be used as indicated by medical

circumstances.

■ only after a prolonged period of circulatory ischemia. In 1970, Kansas became the first state to adopt a brain death statute.3 By 1977, 12 states had enacted laws to accept brain death as sufficient for declaration of a patient's death. In 1978, The National Conference of Commissioners on Uniform State Laws drafted and established the Uniform Brain death Act.3 This act expanded the traditional definition of death (cardiopulmonary) to include brain death. The Uniform Determination of Death Act was introduced in 1978 and approved in 1980. Today, all states have adopted some form of brain death legislation.

+1 0

Post a comment