Nomenklatura científica quer mudar a definição de 'MORTE CEREBRAL'

UMA QUESTÃO EXTREMAMENTE PERIGOSA E PREOCUPANTE: O AFROUXAMENTO DA DEFINIÇÃO CIENTÍFICA DE MORTE CEREBRAL. OBJETIVO: AUMENTAR A 'COLHEITA' DE ÓRGÃOS PARA TRANSPLANTES.

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Editorial

Nature 461, 570 (1 October 2009) | doi:10.1038/461570a; Published online 30 September 2009

Delimiting death
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Abstract

Procuring organs for transplant demands a realistic definition of life's end.

Prompted by the increasing practice of organ transplantation, and thus the need to procure donor organs that are as fresh as possible, many countries have modelled their legal definition of death on a US law passed in 1981 after extensive debate and thoughtful input from a specially appointed president's commission of experts.

The law seems admirably straightforward: "An individual who has sustained either (1) irreversible cessation of circulatory and respiratory functions, or (2) irreversible cessation of all functions of the entire brain, including the brain stem, is dead."

In practice, unfortunately, physicians know that when they declare that someone on life support is dead, they are usually obeying the spirit, but not the letter, of this law. And many are feeling increasingly uncomfortable about it.

In particular, they struggle with three of the law's phrases: 'irreversible', 'all functions' and 'entire brain', knowing that they cannot guarantee full compliance. They do know that when they declare a death — according to strict clinical criteria, the principles of which are outlined in the original report of the president's commission — that the person is to all intents and purposes dead. But what if, as is sometimes the case, blood chemistry suggests that the pituitary gland at the base of the brain is still functioning? That activity has nothing to do with a person being alive in any meaningful sense. But it undermines a claim that all functions of the entire brain have ceased. As do post-mortem observations that relatively large areas of tissue can be metabolically active in different brain areas at the time death is declared.

The criterion of irreversibility raises the question of how long one should wait to be sure that no function will re-emerge. Is the six hours recommended in the commission's report sufficient? Physicians who have been required by circumstance to wait much longer have occasionally observed a brainstem-mediated reflex — a cough, for example — up to 36 hours after they would have declared death.

The problem is that death is not a phase transition whereby a person stops being alive and becomes dead in an instant. It is a long process during which systems, networks and cells gradually disintegrate. At some point, the person is no longer there, and can never be made to return. But the kind of clear, unambiguous boundary assumed in the 1981 law simply does not exist.

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