Are Brain-Dead Bodies Really Dead?
A widely shared conviction is that organisms are alive when their organs function in an integrated way; and that, consequently, death occurs when this somatic unity is lost. In most cases, this point is reached after heartbeat and breathing have stopped and have failed to resume spontaneously. For hundreds of years, this cardiopulmonary criterion had been the standard for determining death, until in the middle of the twentieth century three developments in intensive-care medicine called it into question: the advent of positive pressure ventilation, the promotion of cardiopulmonary resuscitation, and the first successful heart transplantation. What had previously been deemed permanent, suddenly became reversible.
In 1968, an ad hoc committee of the Harvard Medical School ultimately argued that the cardiopulmonary criterion was no longer applicable under these circumstances and suggested that neurological criteria be used instead. This proposal proved to be very influential, and most legal systems around the world adopted brain death as the new standard.
Identifying the destruction of a single organ with the death of the organism as a whole requires an exceptionally well-founded justification. I investigated if such a justification can be given in the case of the brain. I compared brain death with conditions that are universally accepted as constituting living organisms – the persistent vegetative state and anencephaly – to show that cognitive capacities are not essential to organismic functioning and that, hence, only brainstem-mediated functions can be relevant to biological definitions of death. With cognitive capacities excluded, five major differences remain between a brain-dead body and a body in a persistent vegetative state, whose respective significance to integrated functioning I evaluated by contrasting them with high cervical spine transection, locked-in syndrome, bilateral vagotomy, and panhypopituitarism. I concluded that the dissimilarities between bodies in these conditions and brain-dead bodies on life support do not warrant considering the former alive but the latter dead.
I then took these physiological considerations to a more abstract level by introducing a classification of the different ways in which vital functions can cease to be performed. This enables one to see why it is highly problematic to base one’s judgement of whether a biological entity is dead or alive on the status of the neurological control mechanism of a function, rather than on the execution of the task itself: the growing sophistication of life-support systems has given rise to a dangerous decoupling of the performance of a function from the retention of neurological control over it.
Provided that the level of internal coordination between the different organs is still high enough to account for a sufficient degree of somatic unity, the existence of an organism is not conditional on the means by which a certain vital function is directed, but rather on its being performed or having ceased. In intensive-care settings, the status of the brain does therefore not reliably indicate whether an organism is dead or alive since the former need not correspond to the functions that are being carried out in the body – a discrepancy that can yield false positives. I thus concluded that, for these reasons, the brain is not a suitable locus for determining the death of an organism in the presence of extensive life support. Fifty years after its introduction, the neurological criterion is now facing the same fate as its cardiopulmonary predecessor.
Can People Survive in Irreversible Coma?
When a patient fails to emerge from coma, relatives often ask whether their loved one is ‘still here’. What they are inquiring about is not whether the patient is biologically alive since it is usually obvious that this is the case. Rather, they want doctors to tell them whether any mental characteristics remain associated with the body in the hospital bed. In other words: whether the person is still present. While the answer to this question may determine which treatment option is preferable, including whether to discontinue treatment altogether, relatives also want to know whether they are sitting with a psychological subject or an ‘unoccupied’ organism. Should they conceive of the patient analogously to a person in a very deep sleep or should they regard him or her as cognitively akin to a whole-brain-dead individual?
Settling this uncertainty requires that one becomes clear about two issues: the type of functional loss that is associated with the respective profile of brain damage and the persistence conditions of persons. Medical case studies can answer the former question, but they are not concerned with the latter. Conversely, in the philosophical literature, various accounts of personal identity are discussed, but usually detached from any empirical basis. Only uniting the two debates and interpreting the real-life configurations of brain damage through the lens of the philosophical concepts enables one to make an informed judgment regarding the persistence of comatose persons.
Especially challenging are cases in which three mental characteristics that normally occur together – wakefulness, awareness and memory storage – come apart. These are the cases I investigated in this project.
BMJ Blog Post: