Fifty years after Harvard Medical School defined brain death, a new report commemorates the concept and raises new and lasting questions about what it means to be dead as well as implications for organ transplantation.
“Is death defined in terms of the biological failure of the organism to maintain integrated functioning? Can death be declared on the basis of severe neurological injury even when biological functions remain intact? Is death essentially a social construct that can be defined in different ways, based on human judgment?”
These and other issues are discussed and debated in the new report—“Defining Death: Organ Transplantation and the Fifty-Year Legacy of the Harvard Report on Brain Death”—by leading bioethicists, physicians and scientistsin in the field, many of whom have been engaged with this topic for decades.
In 1968, the landmark document, “Report of the Ad Hoc Committee of the Harvard Medical School to Examine the Definition of Brain Death,” proposed a new way to define death, with implications that advanced the field of organ transplantation.
The authors of the 1968 report, under the leadership of anesthesiologist Henry Beecher, stated that their primary purpose was to “define irreversible coma as a new criterion for death.” And though the concept of brain death has guided clinical practice for 50 years, the vigorous debate about its legitimacy has never ceased.
“History is full of ironies, and the 50-year legacy of the Harvard report is no exception,” writes Thaddeus Mason Pope, JD, PhD, health law professor and bioethicist, in his viewpoint essay on the 50-year commemorative report. Other authors of the essay include Robert D. Truog, MD, MA, bioethicist and pediatrician at Boston Children’s Hospital and Harvard Medical School; and David S. Jones, MD, PhD, psychiatrist and professor of the culture of medicine at Harvard University.
“From one perspective, the report laid the foundation for laws that have both saved and improved the lives of hundreds of thousands of patients through organ and tissue donation,” the authors note. “Conversely, decades of attempts to find a conceptual justification for linking this diagnosis to the death of the patient remain incomplete.”
Published in the current issue of the Hastings Center Report, the special report is a collaboration between The Hastings Center and the Center for Bioethics at Harvard Medical School, including editors Truog, the Frances Glessner Lee professor of medical ethics, anaesthesiology & pediatrics and director of the Center for Bioethics at Harvard Medical School; Nancy Berlinger, a research scholar at The Hastings Center; Rachel L. Zacharias, a student at the University of Pennsylvania Law School and a former project manager and research assistant at The Hastings Center; and Mildred Z. Solomon, president of The Hastings Center.
Until the mid‐twentieth century, death was defined in terms of the failure of three critical organ systems: circulatory, respiratory and neurological. “In other words, a person was dead when found to be nonresponsive and without pulse or spontaneous respiration,” the authors wrote. “The diagnosis was simplified by the fact that the loss of any one of these functions quickly led to the loss of the other two. Sudden cardiac arrest quickly led to unconsciousness and respiratory arrest, whereas massive head injury led to loss of respiration and subsequent cardiac arrest.”
But mechanical ventilation and organ transplantation in the 1950s changed everything. “Where previously the loss of the three vital functions had been essentially simultaneous, mechanical ventilation made it possible to maintain respiration and circulation in a person who otherwise would have perished quickly from a brain injury that caused loss of spontaneous respiration,” the report says. Patients determined to be dead by neurologic criteria, and have consented to donate their organs could now do so, since death is declared while the organs are being kept alive by a ventilator and a beating heart.
This led to numerous organizations around the world in the mid-1960s beginning to contemplate the concept of “brain death.” The effort in the United States was led by Beecher at Harvard Medical School, and resulted in the publication of the 1968 Harvard report to determine brain death.
The authors note that early responses to the report were “varied and often passionate.” A 1971 Hastings Center task force endorsed the need for a means to determine death by neurological criteria but did not agree on everything. “Some commentators felt that the question was a philosophical one, not one that could be settled by medical facts alone, and argued for going further than the Harvard report, by accepting the loss of higher brain function as a sufficient criterion to define death,” the new paper reports. “Hans Jonas agreed that life supports could be withdrawn from persons permanently unconscious, but criticized the Harvard committee for labeling such persons dead.”
Health care workers still use tests similar to the ones set out by the original Harvard report to determine when a patient is brain‐dead:
- They confirm that the patient is unconscious, that is, that there is no evidence that the person can perceive or respond to any stimulus.
- They demonstrate the loss of key brainstem functions, the most important of which are the respiratory centers that drive spontaneous respiration.
- They demonstrate that the condition is permanent by ruling out any potentially reversible conditions, such as drug intoxication or hypothermia. Conceptually, therefore, brain death can be thought of as “permanent apneic unconsciousness.”
And the report stands by its conclusions. “Year after year, there are media reports about patients who have been diagnosed as ‘brain‐dead’ and who have apparently experienced miraculous recoveries,” researchers say. “In every case, careful examination of the evidence has shown these reports to be false. To date, there has never been a case in which brain death was correctly diagnosed and the patient subsequently recovered any neurological function whatsoever.”
Researchers say inaccurate use of the term “brain death” has contributed to public misunderstanding of this neurological state. “Unfortunately, the term ‘brain‐dead’ has acquired a colloquial meaning, representing any sort of impairment of neurological functioning, from a severe brain injury or disorder of consciousness to a temporary lapse of memory. And even experienced reporters and editors may confuse brain death with other neurological states following brain injury.”
The Uniform Determination of Death Act (UDDA), proposed by the President’s Commission, has now been adopted in some form in every state in the union. But it wasn’t always that way. Kansas was the first state to adopt the criteria of the act in 1970, following publication of Harvard’s 1968 report. “Over the rest of that decade, many states developed criteria in a patchwork and inconsistent fashion, making it possible to be legally alive in one state and legally declared dead in another,” the new report states. “To resolve this confusion, in 1981 the President’s Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research was formed to develop model language, reflecting medical standards, for state law.”
The UDDA states that an individual who has sustained either:
- an irreversible cessation of circulatory and respiratory functions, or
- an irreversible cessation of all functions of the entire brain, including the brain stem, is dead.
The act goes on to specify different criteria for determining death including: cardiorespiratory criteria and neurological criteria. “These two criteria map onto the two main pathways for organ donation. In the brain death pathway, death is determined on the basis of neurological criteria, and the patient is declared dead while still on the ventilator and while the organs are being perfused and oxygenated. This permits the retrieval of all vital organs (heart, lungs, kidneys, liver, small bowel, and pancreas) under optimal conditions.”
In the donation after circulatory determination of death (DCDD) pathway, typically, patients who have suffered a devastating neurological injury but who do not meet criteria for brain death have life support withdrawn in a controlled fashion. They are then observed for the onset of pulselessness, which must occur within about an hour for the organs to be useable. Once pulselessness occurs, they are observed for an additional five minutes to be sure that the heart will not start again on its own (autoresuscitation). If this does not occur, they are declared dead, and organ procurement begins.”
Since 1981, much of the controversy about brain death has revolved around the question of whether brain-dead donors are really dead. James Bernat, emeritus professor of medicine and neurology at the Geisel School of Medicine at Dartmouth, originally argued that brain death quickly leads to the loss of functioning of the organism as a whole, such that brain death literally results in the disintegration of the body, regardless of the degree of medical support provided. D. Alan Shewmon, emeritus professor of pediatrics and neurology at the David Geffen School of Medicine at UCLA, disagrees and has developed a series of cases showing that the bodies of patients diagnosed as brain‐dead do not necessarily “disintegrate,” as long as they are provided with mechanical ventilation and tube feedings. He contends that such patients may “retain integrated functioning, including growth and development, wound healing, infection fighting, and gestation of a pregnancy, such that some of these patients may continue to have biological survival for many years.”
Bernat acknowledges some of Shewmon’s arguments, but nevertheless provides a modified argument for why brain death still represents the loss of functioning of the organism as a whole, offering distinctions between the concepts of permanence and irreversibility. “Permanence is understood as a situation that will progress to irreversibility in the absence of an attempt to reverse it,” he writes. “Irreversibility implies that the situation cannot be reversed even if attempts are made to do so.”
Ari Joffe, clinical professor in the department of pediatrics at the University of Alberta, provides several arguments in the new report for why the permanence standard is conceptually flawed and, therefore, why we “cannot assume that DCDD organ donors are dead at the time their organs are procured.”
In the United States, DCDD protocols have mostly been used only when life support is withdrawn and with the consent of the patient’s surrogate. Though some European health care systems have been experimenting with “a more aggressive form of DCDD, where patients who have experienced unexpected cardiorespiratory arrest out of the hospital are enrolled in protocols to preserve their organs for transplantation once emergency response physicians determine that their chance for survival is nil,” the new report states.
So when is it acceptable to stop trying to save the life of the patient and shift the purpose of the resuscitation to saving the organs for transplantation? And why does it matter? The new report says some scholars have argued that the problem is not with the criteria themselves but with the underlying assumptions of the so‐called “dead donor rule” (DDR) which requires that donors be dead before their organs are procured. They point out that any violation of the rule would be considered voluntary euthanasia, currently prohibited in the United States.
Still, debates about whether organ donors are dead make the presumption that we have a biological understanding of what it means to be dead. “While we commonly think about death in biological terms—the death of the body—human death means more than the death of the biological organism,” the new report states. “When a person dies, their essence disappears, and others’ experiences of them change. Those who continue to live mourn the loss of more than a body. So some scholars have questioned why we privilege a purely biological understanding of death. Instead, they argue that death is experienced as both a biological and a social process, involving rituals such as funerals, a period of mourning, the reference to a surviving spouse as a ‘widow’ or ‘widower,’ and the issuance of a death certificate, among many other sequalae. Therefore, the definition of death should reflect both biological and social factors and, further, should acknowledge that all patients, families, or social groups may not hold the same values concerning when death occurs.”
Considering the increasing legal challenges to when a person is legally dead, some contributors to the report argue that individuals should be allowed to choose their own definition of death within a range of options. Another explores how religion and culture shape our experience of personal identity and death. And still another offers the perspective of a bioethicist who has long observed debates over the end or continuation of life.
The report goes on to discuss the possible development of virtually inexhaustible sources of transplantable organs, through xenotransplantation (the process of grafting or transplanting organs or tissues between members of different species, ie. animals) or other technologies such as tissue engineering and 3-dimensional printing which could yield synthetic organs. By eliminating the need for human donors to serve as a source of transplantable organs, most of these areas of controversy and concern about the diagnosis of brain death for organ procurement covered in the report itself would become irrelevent.
“Until then, however, one warning remains apt,” writes Pope, “Capron, one of the architects of the UDDA, summarized the situation well in 2001 when he described efforts to determine when death has occurred as both ‘well settled, yet still unresolved.’”