"Brain death"
A lie destined to die

SCIENTIFIC APPROACH TO JUDGING THE SO CALLED " BRAIN DEATH"

Evolution of the Concept of Brain Death

Over the centuries people were deemed dead when they stopped breathing and when their hearts stopped beating. But the technological advances enabled artificial substitution of those functions temporarily aiming to buy time while the original insult

( whether brain insult or otherwise) was taken care of Victims of brain insults posed a problem while. their lives were artificially sustained by machines : they failed to regain consciousness and spontaneous Breathing. brain death was frist described by French  neurologists and neurophysiologists at the  end of the 1950 s’  )1.2) Renal transplantation was then in its infancy. It is important to point out that this was not  just a mere coincidence Many critiques (3.4) of brain death  share the opinion that if it were  not for the ever- growing need for organ donation the concept of brain death wouldn’t have emerged or survived.

The end of the 1960’s  was also prominent for further advances in this area the Ad hoc committee of the  Harvard medical school proposed for the first time, a new  definition  of death on neurological grounds. The Harvard’s report appeared some months after Christian Bernard’s  first transplantation of a human heart. in December 1967 The   year  of 1981 was highlighted by the report of the president’s  commission for the study of ethical problems in medicine and behavioral  research to define death  the 1980 ‘s and the early 1990 ‘s were characterized by multi – disciplinary debates (5)

DEATH   FORMULATION

 A Formulation of death must have three components : A concept or definition of what it means to die . the criteria for determining that death has occurred and the specific  medical tests showing whether the criteria have been fulfilled or not (6)

A.   Classical  Death:

  As regards definition; this denotes the irreversible loss of function of the whole organism in religious terms This coincides with the departure of the soul from the body .In technical terms,  death has been defined  in the 22 nd world medical assembly in Sydney. 1968  as: ‘ A gradual  process at the cellular level with tissues varying in their ability to withstand deprivation of oxygen ‘ (5) This definition discriminates between “ dying “ ( a process ) and “ being dead “ ( a state ) and indicates that different tissues die at different rates after permanent deprivation of their blood supply(7),

        As regards the criteria of classical death. these are divided into early and late signs These criteria are derived from Islamic sonna and are dictated by legal medicine. Early signs include signs of respiratory and circulatory arrest together with  gradual coolness of the body and cessation of all body activities. Late signs are the sure signs of death and include rigor mortis and signs of putrefaction (fauna of the cadaver etc ...)

       All the tests and tools that are necessary to verify death are simple bedside tests (also derived from Islamic sonna ) and perhaps a stethoscope and a thermometer in the early phase of death .

 It is to be noted that when sure signs of death appear, diagnosis of death is  unmistakable.

B.   Brain Death

When it comes to brain death .all three components of death formulation are still  controversial as clearly stated by Prof. Calixto Machado (8) , president of the organizing committee of the 2 nd international symposium on brain death held  in Havana Cuba in February 1996 : “ there were still worldwide controversies about a concept of human death on neurological grounds ( whole brain, brain stem death  and higher brain formulations of death ) . There was also  disagreement on the diagnostic criteria of brain  death , whether clinical alone or clinical and ancillary tests’

-Controversies Concerning the definition of brain death:

      According to the 1 st and 2 nd international symposia on brain death held in Havana, Cuba in 1992 and 1996 (8) there are three recognized definitions for brain death:

1-       Whole brain death  which implies death of every neuron in the  intracranial   cavity.

2-       Brainstem death which implies damage of the brain stem alone ( not necessarily denying the  viability of other parts of the brain).

3-       “ Higher brain death “ or cognitive death which implies brain damage which leads to “ irreversible loss of that which is essentially significant to the nature of man; cognition  “ this  definition was proposed in the united states and failed to gain popularity because it represented “ the first step  along a slippery slope : as the  authors of the  “ ABC”  OF Brain  stem death” (5) stated . they argued “ if one starts equating the loss of higher  functions with death , then which higher functions ? Damage to one hemisphere or both ? if to one hemisphere, to the “ verbalizing “ dominant one or to the  “ attentive “ non- dominant one ? one soon starts arguing frontal versus parietal lobes “. ( to  my opinion this 1 st step has already been taken by the mere proposition of such a definition in such  big meeting as the 1 st an 2 nd international symposia on brain death ).

   The first two definitions are the ones adopted in practice .   

        death of the whole brain appeared first as has been  

        documented by the Harvard   criteria of brain death in 1968  ( table 1) 

Table 1 (5)

 The Harvard criteria demanded that the patient should be unreceptive and unresponsive, the most intensely painful stimuli evoking “ no  vocal or other response, not even a groan, withdrawal of a limb or quickening of respiration “ . No movements were to occur during observation for one hour. Apnoea was to be confirmed by three minutes off the respirator ( the centrality of apnoea. properly defined and  tested for , had  already been appreciated ). The quantification in terms of PaCo2 levels  reached during disconnection tests came only much later as a result of British experience. The Harvard criteria also required that there should be “ no reflexes “ the emphasis being on brainstem reflexes a flat or isoelectric electroencephalogram at high gain was of “ great  confirmatory value “ . All the tests were to be repeated at least 24 hours later with no changes in the findings.

     In (1971) the Minnesota criteria (table 2) appeared and replaced the Harvard criteria.

Table 2 (5)

     The Minnesota criteria introduced the notion of aetiological preconditions. ( twenty of their 25 patients had  sustained massive craniocerebral trauma and the remaining five were suffering from other primary intracranial  disorders ). They emphasized the importance of apnoea in the determination of brain  death :  in fact they insisted on four minutes   of disconnection from the respirator. ( alarmingly to us today , they did not mention pre- oxygenation before disconnection or diffusion oxygenation during the procedure ) . They demanded absent  brainstem reflexes, stated that the findings should not change for at least 12 hours and emphasized that the electroencephalogram was not mandatory for the diagnosis. Eversince 1971 doctors have sought to identify the necessary and sufficient component ( or physiological kernel) of brain death. This was dictated, perhaps by a philosophical assumption which considered human death to be a state in which there is irreversible loss of capacity for consciousness combined with  irreversible loss  of capacity to breathe spontaneously ( and hence to maintain a spontaneous heart beat ) (5) Eventually whole brain death was substituted by brainstem death as the brainstem came to be recognized as      “ the critical system of the  basic critical system” propositions for irreversible brain stem function are listed in table (3)

Table 3 (5)

The functions of the brain stem are referred to in brief in table (4)

Table 4 (5)

Screening the present positions of different countries concerning the adoption of the concept of brain death readily reveals that  there are two main approaches to brain death which prevail worldwide , namely the united kingdom and the American collaborative study (1977 )  approaches (5) These have been summarized in table (5).
 

Table 5 ( 5)

 Table 6 (5)