Death: Still Irreversible After All These Years

By Nada Gligorov

Image courtesy of Neil Conway, Flickr

In a recently published article in Nature, Vrselja et al. (2019) describe a system named BrainEx (BEx)—a combination of surgical procedure, perfusate, and custom pulsatile-perfusion device—to restore and maintain circulation and cellular viability in ex vivo pig brains. They observed that the use of BEx reduced cell death, preserved neural and cellular integrity. They also found that some cellular functions were restored, which was indicated by vascular and glial responsiveness to pharmacological and immunogenic intervention, spontaneous synaptic activity, and cerebral activity. The authors were clear, however, that BEx did not restore any global brain activity that could lead to the restoration of perception, consciousness, or any other higher-order brain functions. The significance of this study, according to Vrselja et al. (2019) is that, with appropriate intervention, the mammalian brain retains a better capacity for metabolic and neurophysiological recovery after anoxic or ischaemic injury than previously thought. Because brain death is often the result of severe anoxic or ischaemic injury to the brain, the results of this study were quickly reported in the media where some articles examined whether the study challenges brain death as biological death of the organism. In order to assess whether this study has any bearing on brain death, I will clarify the meaning of irreversibility in the biological definition of death. I will also show that irreversibility of brain death needs to be interpreted as applying narrowly only to current possibilities of restoration of neurologic function. Establishing the precise interpretation of irreversibility is important to stem the premature undermining of brain death as biological death, and as a legal criterion for death, that might arise as the potential for reversibility moves slightly out of the realm of science fiction.

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James Bernat, a neurologist and a proponent of the view that brain death is biological death of the organism, provided the following definition: “Death is the irreversible and permanent loss of the critical functions of the organism as a whole” (Bernat 2006, p. 36). Given that the brain is required for the critical functions of the organism, the death of the entire brain is the end of those critical functions, and it is the cessation of function of the organism as a whole. The view that brain death is equivalent to biological death remains contested in the bioethics literature and some commentators argue that brain death is not biological death (Collins 2010; Shewmon 1998; 2004; 2010). Bernat (1998) has argued further that any conception of death, including the commonsense notion, requires irreversibility. On the other hand, David Cole (1992) has argued that the ordinary notion of death does not require irreversibility. Cole argues that death is not irreversible because it is not a contradiction to think of it as a reversible event based on how we speak about it in our everyday lives. Some religious individuals, for example, believe that the dead might be brought back to life through resurrection. Hence, for individuals with those religious beliefs it is not a contradiction to say that an individual is dead and that death could be reversed through resurrection. According to Cole, the scientific notion of death, specifically brain death, is a stipulated conception of death that is specifically devised to serve clinical or scientific purposes. Additionally, he argues that ‘irreversibility’ in the biological definition is ambiguous. It is not clear whether reversibility refers to any conceivable possibility or if it refers only to currently available methods that could reverse the demise of an organism. Based on the scope of irreversibility, we might have different obligations to patients who are dead. For example, if we think of irreversibility as covering any conceivable possibility, we might have the obligation to cryopreserve all individuals at the time of death in case in the future a method is discovered that could be used to revive them.

As I have argued previously (Gligorov 2016), commonsense conceptual frameworks have many of the same features as scientific theories and because of that it is difficult if not impossible to distinguish reliably between ordinary notions or scientific notions in almost any domain. Furthermore, there is not a universally accepted ordinary or commonsense notion of death as there are cultural and contextual differences that hamper efforts to precisely define any commonsense concept. In addition, I maintain that ordinary notions of death are shaped by biological characterizations of death. This is particularly evident in clinical and medical contexts where most everybody accepts the biological conception of death, especially in circumstances where the cause of death is end of cardiac function. In clinical settings, both families and physicians rely on the biological conception of death in order to make medical decisions.

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But if we presume for the sake of argument that there is an ordinary notion of death and a biological conception of death and that the two concepts can be distinguished, then it is even easier to argue that the appropriate interpretation of irreversibility in the biological definition of death should be based on biologically determined possibilities and should not be taken to include all conceivable possibilities. In other words, biological conceptions of death are restricted to only what is currently biologically or physically possible. Conceivability of resurrection, for example, extends the realm of possibilities outside of what is scientifically possible and is irrelevant. When we say now that an individual has suffered an irreversible loss of organismic function, we mean to say that given current scientific understanding and given current ability to restore function to the brain or to the heart the individual is dead. Cole’s proposed strong interpretation of irreversibility as including any conceivable future possibility clearly does not apply in situations when we use the biological notion of death. Both the biological notion of death and obligations to patients are restricted to only those possibilities that are permitted by our understanding of human biology and even narrower to the current biological understanding of which biological events or processes in the body are reversible. The advancements described by Vrselja et al. (2019) do not challenge irreversibility of brain death as currently characterized because, as they clearly state in their article, they have not demonstrated restoration of global brain function.

Construing irreversibility as being limited to current biological possibilities implies that developments in biology and medicine can change the understanding of which events or processes in the body are reversible. We can see that such changes have already occurred in some clinical situations with the irreversibility of the loss of cardio-pulmonary function. For example, the functions of the lungs can be replaced by ventilators, and heart function can in some cases be supported by pacemakers or artificial pumps. More recently extracorporeal membrane oxygenation (ECMO) is sometimes used to continue circulation and the supply of oxygen to the body for individuals whose heart or lung are temporarily unable to continue oxygenation and circulation of the body. These advances prevent death by either supporting or supplanting the function of a heart or a lung, the loss of which, without intervention, would lead to death.

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The complete loss of neurologic function required for the diagnosis of brain death, however, remains currently irreversible. Bernat (1998) goes even further and claims that the functions of the brain could not in principle be supplanted by artificial processes. But this conclusion is too strong. By claiming that neurologic restoration is in principle impossible, Bernat discounts an inappropriately large realm of possibilities. It is surely conceivable that brain function could be replicated or supplanted in such a way that the memories and personality traits of an individual would be preserved. In fact, lots of science fiction trades precisely on this conceivability, including movies like Transcendence or Black Mirror’s Be Right Back. What is false is that there is an established physical possibility of neurologic restoration that could achieve such preservation of psychological function. Although the biological possibility of reversal of neurologic demise has not yet been established, perhaps the preservation and restoration of cellular function through BEx is a very early step in establishing the potential of restoration of global neurologic activity after ischaemic or anoxic brain damage. Still, it is important to keep in mind that future possibilities for such restoration do not undermine the current irreversibility of brain death. 

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Nada Gligorov is an associate professor in the Bioethics Program of the Icahn School of Medicine at Mount Sinai. She is also faculty for the Clarkson University-Icahn School of Medicine Bioethics Masters Program. The primary focus of Nada’s scholarly work is the examination of the interaction between commonsense and scientific theories. She is the author of Neuroethics and the Scientific Revision of Common Sense (Studies in Brain and Mind, Springer). In 2014, Nada founded the Working Papers in Ethics and Moral Psychology speaker series–a working group where speakers are invited to present well-developed, as yet unpublished work.

References

1. Bernat, J. L. (1998). A defense of the whole-brain concept of death. Hastings Center Report, 28(2), 14–23.
2. Bernat, J. L. (2006). The whole-brain concept of death remains optimum public policy. Journal of Law, Medicine, and Ethics, 34, 35–43.
3. Cole, D. (1992). The reversibility of death. Journal of Medical Ethics, 18, 26–30.
4. Collins, M. (2010). Reevaluating the dead donor rule. Journal of Medicine and Philosophy, 35(2), 1–26.
5. Gligorov, N. (2016). Rethinking Commonsense Conceptual Frameworks. In Neuroethics and the Scientific Revision of Common Sense (pp. 15-33): Springer.
6. Shewmon, D. A. (1998). Chronic “brain death”: Meta-analysis and conceptual consequences. Neurology, 51, 1538–1545.
7. Shewmon, D. A. (2004). The “critical organ” for the organism as a whole: Lessons from the lowly spinal cord. In O. Machado & D. A. Shewmon (Eds.), Brain death and disorders of consciousness. New York: Kluwer Academic/Plenum Publishers.
8. Shewmon, D. A. (2010). Constructing the death elephant: A synthetic paradigm shift for definition, criteria, and tests for death. Journal of Medicine and Philosophy, 35, 256-298.
9. Vrselja, Z., Daniele, S. G., Silbereis, J., Talpo, F., Morozov, Y. M., Sousa, A. M. M., . . . Sestan, N. (2019). Restoration of brain circulation and cellular functions hours post-mortem. Nature, 568(7752), 336-343. doi:10.1038/s41586-019-1099-1

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Gligorov, N. (2019). Death: Still Irreversible After All These Years. The Neuroethics Blog. Retrieved on , from http://www.theneuroethicsblog.com/2019/06/death-still-irreversible-after-all.html