oxford handbook of bioethics
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O F L I F E
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T H E D E F I N I T I O N
O F D E AT H
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S T UA RT J . YO U N G N E R
INT RO DUC T I ON
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UNTIL the invention of the stethoscope and the acquisition of knowledge about human anatomy in the early nineteenth century, physicians were unable to diagnose death with precision. The ability to do so provided them with great credibility from a public that had, until then, been concerned about premature burial.
Significant uncertainty and debate about the definition and determination of death did not resurface until the latter half of the twentieth century, again owing to the state of medical science. But this time, physicians knew too much, rather than too little, about the pathophysiology of the dying process. In the modern intensive care unit (ICU), they have been increasingly able to break down the dying process, teasing apart each of its component parts and supporting some functions while providing technological replacement for others. In the intensive care unit, death approaches as much on the electronic screens of heart, brain, and blood pressure monitors as it does in the failing bodies of patients.
These developments have had two important consequences. First, the cascade of events that previously led to death is no longer inevitable. Before, if one vital function ceased, the others quickly followed, removing the necessity of choosing one as more ‘vital’ than the other. Today, the mechanical ventilator, the cardiac pacemaker, drugs that maintain blood pressure, and many other interventions keep
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the body ‘going’ after loss of innate functions that formerly would have meant the cessation of them all. The second consequence is the incredible control such monitoring and support gives physicians, patients, and families over the timing of death. Once thought to be in the hands of God or fate, the time of death is now most often a matter of deliberate human decision. This understanding and control, while never able to defeat death, gives human beings the illusion of control over death and an uneasy sense of responsibility, however it arrives.
Two factors, medical science’s growing control over the timing of death and the increasingly desperate need for organs, have led to a reopening of the debate about the definition of death and have forced consideration of aspects of the determination of death that had never been addressed before. Without the pressing need for organs, the definition of death would have remained on the back shelf, the conversation of a few interested philosophers or theologians.
In the discussion that follows, we will examine some new questions raised by medical technology and the frantic search for new, morally acceptable sources of human organs over the past thirty years. This examination will lead us to conclude that death itself is a social construct and that, in a pluralistic society such as ours, a conclusive definition of death or determination of the moment of death is out of the reach of both medical science and philosophy.
PHILOSOPHICAL DEfiNIT IONS OF DEAT H
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Philosophers have argued convincingly that the definition of death, while grounded in human biology, is, ultimately, a philosophical question. To define death, one must answer the question ‘What function(s) is (are) so essential that its (their) irreversible loss signifies (signify) the death of the human being?’ Once a correct definition of death is chosen, an operational criterion can be selected for determining that the definition has been fulfilled. At an even more operational level, specific clinical tests can be done to assure that the criterion has been fulfilled.
Specific criteria and tests are valid only because they fulfill a philosophically defensible definition. So, for example, if one argued that consciousness and cognition were the unique functions that differentiated a living person from a corpse, the corresponding criterion would be loss of functioning of the higher brain. Specific tests to demonstrate that this criterion had been fulfilled might include non-responsiveness of the patient, a flat EEG, and a brain scan showing destruction of those parts of the brain responsible for consciousness and cognition. If this definition, loss of consciousness and cognition, is wrong, then the corresponding criteria and tests are ‘wrong’ as well. Conversely, no criterion can stand alone. It must be supported by a philosophically sound concept answering why it measures
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the difference between a living human being and a corpse. For example, a claim that irreversible loss of all liver function was the correct criterion for measuring death would be absurd. Persons with no liver function may be dying, but they breathe, their hearts pump blood, and they can still talk, read, and suffer.
In addition to loss of consciousness and cognition, there are two other philosophical notions of what it means to be dead. The first is loss of vital fluid flow — the circulation of blood and oxygen through the body. The corresponding criterion is irreversible cessation of cardiopulmonary function that might be tested by listening for breath sounds, feeling for a pulse, or performing an electrocardiogram. The vital fluid flow definition dominated from the early 1800s until the early 1970s. The other definition is loss of functioning of the organism as a whole. The corresponding criterion is irreversible loss of all brain function, including that of the brain stem. Tests to see that that criterion has been fulfilled might include examination of brain stem reflexes, EEG, or scans to see if all blood flow to the brain has ceased.
Each of the three definitions has its adherents in the United States and the rest of the world, although the whole brain formulations have been enshrined in law in the United States and many European countries through recognition of so-called ‘brain death’. Before going on to discuss brain death in greater detail, an observation is in order.
The Implications of Stretching Out the Physiologic Events
Surrounding Death
Until the advent of the mechanical ventilator and the modern intensive care unit, when one vital function ceased, the others stopped quickly and, to the unsophisticated eye, simultaneously as well. It all happened at once. For example, if someone had a sudden heart attack and cardiac arrest, the person stopped breathing and lost consciousness (owing to lack of oxygenated blood to the brain). Similarly, if breathing ceased, loss of consciousness quickly followed, and the heart, also deprived of oxygen, stopped beating within minutes. If someone sustained a massive head injury (stroke, gunshot wound), he or she immediately stopped breathing because spontaneous respiration is controlled by a center in the brain stem. The heart, deprived of oxygen, stopped within minutes. Thus, we never had to choose between vital fluid flow, function of the organism as a whole, or consciousness and cognition as the key function that distinguished life from death.
With medical intervention, these events no longer take place simultaneously. If a person has a heart attack, we can resuscitate them, put them on a mechanical ventilator, and shock or pump on the chest to restore circulation to the brain. Respiratory arrest can be treated with mechanical intervention. Most relevant here, following an acute and catastrophic brain injury, we can now mechanically ventilate a patient, preserving heart but not brain function.
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This latter category, patients who have lost all brain function, including that of the brain stem, but are maintained with life support, is called brain death. Braindead patients’ hearts continue to beat spontaneously, they breathe with the aid of a ventilator, and, in many other ways appear to be alive. Their kidneys produce urine, their pancreases produce insulin, their livers metabolize waste products in the blood, etc. In the early stages of pregnancy, such ‘dead’ patients can gestate fetuses for months until they are capable of living ex utero. Although initially considered very unstable, better technology, persistence, and demands of family members have kept some brain-dead patients ‘alive’ for up to ten years.
As we shall see, the ‘discovery’ of so-called brain death was a direct consequence of the invention and employment of the mechanical ventilator in patients who had sustained catastrophic head injuries. Maintaining such patients provided both a problem and an opportunity. The problem was that when ventilators were first deployed in the late 1960s, we had no legal, professional, or cultural experience with turning them off. To many, it seemed that to do so would mean killing the patient. Coincidentally, the severely brain-damaged patients, now maintained on ventilators, were a potential source of organs for transplantation.
BR A I N DE AT H I N T H E UN I TE D STATE S
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In 1968 an ad hoc committee at the Harvard Medical School proposed ‘a new criterion for death’: total and irreversible loss of functioning of the whole brain (Ad Hoc Committee 1968). This proposal came as a result of a new class of patients inhabiting intensive care units — patients with massive brain injuries who were being sustained by mechanical ventilators and aggressive ICU staff. Interestingly, the Harvard Committee proposed only a criterion of death with no corresponding definition. In other words, they did not ask or answer the question ‘What is the critical characteristic of brain-dead patients that makes them dead?’ Instead, they made it explicitly clear that they were trying to solve two practical problems: (1) to relieve the ‘burden’ imposed by severely brain-damaged patients; and (2) to quell the ‘the controversy in obtaining organs for transplantation’. Let us examine these practical problems in order.
Relieving the Burden
Mechanical ventilators had just come into use in the 1960s. In many instances, they were able to stabilize patients not otherwise able to breathe, allowing critical medical treatment, removal from the ventilator, and discharge home from the hospital. In other cases, however, patients could not be ‘weaned’ from the ventilator. Examples included people at the end-stages of terminal illnesses such as metastatic cancer or
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heart failure, or, more to the point here, patients with massive head injuries whose lungs and hearts were working fine.
It may be hard to imagine now, fifty years later, when ‘terminal’ discontinuation of mechanical ventilation is an everyday event in modern ICUs, but in the 1960s our society had no legal, clinical, or cultural experience with turning off ventilators. There were no court cases, no laws, no professional guidelines, and no hospital policies. The Harvard Committee clearly believed that reclassifying some of these patients as ‘dead’ would avoid charges of homicide when they were allowed to die by ‘pulling the plug’.
Quelling the Controversy
By the late 1960s organ transplantation was becoming a reality. One of the obstacles was (and remains) a shortage of potential donors. Patients who died of cardiorespiratory arrest were not adequate organ sources. After the heart and lungs stop, oxygenated blood no longer flows to the body’s organs and tissues. However, the cells in those tissues and organs continue to metabolize in the cooling, but still warm, body, but without the benefits of oxygen, nutrients, and a way to get rid of waste products. Thus, warm ischemic (without blood) damage occurs and, as a result, by the time they are removed, organs are no longer fit for transplantation. Until the invention of brain death, organs came primarily from live donors, and, at first (because of immunologic incompatibility), only from identical twins.
As noted earlier, patients with massive brain destruction, maintain their heartbeats on ventilators, and have healthy and functioning hearts, kidneys, livers, lungs, and pancreases. It was precisely these characteristics that made them an attractive new source of organs. But, if they were not dead, removing vital organs would surely kill them, violating an unwritten but powerful rule that governs organ transplant to this day — the dead donor rule. The dead donor rule states that patients may not be killed by or for removal of their organs for transplantation. Violating this rule would have provoked the controversy the Harvard Committee proposed to ‘quell’.
Amazingly, their radical new proposal was embraced by the legal and medical communities in the United States, all major religious groups, and, seemingly, the public — with very little controversy or even discussion. Within two decades, brain death became a legal standard of death throughout the United States and allowed a tremendous expansion in organ transplantation. Why this was so is an interesting question. In Japan, as we shall discuss in detail later, the opposite is true. Japan has only recently adopted a highly controversial and, largely, ineffective law linking brain death and transplantation.
It is likely that a number of factors combined to ease acceptance in the United States. First is the practical or utilitarian bent of American society, with its great enthusiasm for the ‘advances of medical science’. Second, there was no natural political constituency to oppose it. As Courtney Campbell (1999: 199) has written:
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It can be questioned why such religious opposition did not emerge . . . The time frame is very important. One cannot speak of a politically mobilized and socially active fundamentalist movement until after the Roe v. Wade decision legalizing abortion in 1973, some 5 years after the report of the Harvard committee. Nor was euthanasia a realistic end-of-life option for patients until very recently.
Campbell notes that the current cultural climate is quite different. Currently, religious conservatives criticize today’s social ethos as an embrace of the ‘culture of death’ and apply a much more vigorous and carefully developed analysis to the issues of abortion and euthanasia than they ever did to brain death.
Lastly, although brain death is, as we shall see, tremendously flawed from a philosophical and clinical perspective, it has practical characteristics that make it acceptable to different people for different reasons. First, unlike its cousin condition, persistent vegetative state (PVS), with which it is often confused, brain death is a relatively quick and easy diagnosis to make. Patients can reliably be pronounced brain-dead within hours of initial diagnosis. Moreover, once the diagnosis is made, the prognosis is entirely clear. Brain-dead patients will never wake up and they will never breathe on their own. In fact, they are notoriously unstable and, even maintained on ventilators, will often suffer cardiac arrest and cardiovascular collapse within hours or days of diagnosis. So, the diagnosis of irreversibility is certain and, even if one believed in a cardiopulmonary criterion of death, cardiac arrest would predictably come very soon on the heels of a brain death diagnosis. For the vast majority of people, the quality of life for brain-dead patients, ICU dependent and forever unconscious, is unacceptable. Finally, although the Harvard Committee attempted no definition of death with which to justify its criterion, the brain death criterion can actually satisfy two competing definitions, making it acceptable to a wider number of persons.
The first definition to justify the whole brain criterion was proposed by Bernat and his colleagues in 1981 — thirteen years after the whole brain criterion was first proposed by the Harvard Ad Hoc Committee, surely the case of a criterion in search of a definition (Bernat et al. 1981). Bernat said that the quality absent in brain-dead patients that made them dead was ‘permanent cessation of functioning of the organism as a whole’, that is, ‘the spontaneous and innate activities carried out by all or most subsystems’ and ‘the body’s capacity to organize and regulate itself ’. Examples given included neuroendocrine control, temperature regulation, and the ability to maintain blood pressure and fluid and electrolyte balance — all functions of the brain stem. Thus, Bernat saw the critical brain function as the ability to integrate the body’s non-cognitive vegetative functions, thereby maintaining homeostasis. Although justifying a ‘whole brain’ criterion, Bernat gave no significance to another important brain function, consciousness and cognition. Bernat’s definition was quickly endorsed by a President’s Commission whose report facilitated the widespread acceptance of brain death (President’s Commission for
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the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research 1981).
In a simplified way, the brain has two major functions: the integrative functions of the brain stem so important to Bernat and the President’s Commission, and the capacity for consciousness and cognition. The integrative capacity resides primarily in the brain stem, the smaller, more primitive part of the brain buried beneath the much larger cerebral hemispheres where cognitive capacity largely resides. These are sometimes referred to as the lower brain (brain stem) and higher brain (cerebral hemispheres). Many persons think that permanent loss of consciousness and cognition is the critical one that makes brain-dead patients dead. However, when patients become brain-dead, they lose both consciousness and cognition and integrative capacity. Thus, a brain-dead patient satisfies both camps and does not force a choice between higher and lower brain functions as necessary and sufficient for death.
There has been little intellectual support in the philosophical and bioethics literature for Bernat’s position. In fact, in the twenty-five years since Bernat’s whole brain formulations were introduced, philosophic thought and clinical experience have largely refuted them. However, because of its wide appeal for a variety of practical reasons, rejection of brain death has been confined primarily to academic circles; in the United States there have been no significant challenges to brain death as public policy.
Philosophical and Clinical Challenges to the Whole Brain Formulations
Philosophers have savaged the formulations of Bernat and his colleagues on several counts. First, while they agree that the ability of the brain stem to integrate the body’s subsystems is necessary to maintain life and that without it the person would die very quickly, dying is not the same as death. Moreover, integrative function hardly defines what it means to be a living human being. Consciousness and cognition alone, they argue, are the necessary and sufficient conditions (Bartlett and Youngner 1988; Gervais 1986).
Consider the following thought experiment. A patient has severe damage to the brain stem but not cerebral hemispheres and, therefore, has lost only the innate integrative brain functions so dear to Bernat. However, these brain stem functions are being carried out by the mechanical ventilator and a highly trained ICU staff. For example, the nurses monitor blood pressure; when it drops, the patient is given drugs to raise it. However, unlike a ‘brain-dead’ patient who has lost all brain function, this patient remains conscious and can respond to our questions. She has lost all the spontaneous and innate functions Bernat identifies as essential, yet she is aware and can communicate. So, while the patient does not meet Bernat’s