In most countries, death can be diagnosed by either cardiorespiratory or brain criteria. The fact that two definitions are accepted is remarkable and can only be understood in an historical context. Paradoxically, we do not have a common and accepted definition for life. Indeed, the scientific demarcations that we create make it impossible to agree on a single definition. Drawing lines between morula and blastocyst, or an embryo and a fetus are scientific inventions that assist the embryologist but are also easy marks for political rhetoric. If we cannot agree on a definition of life, the belief that we have agreed on a definition of death is fanciful. Both life and death are probably best defined as global states that are gradually approached rather than lines that are crossed. So why have we come to such an acceptance of death by both cardiorespiratory and brain criteria?

A CONCISE HISTORY OF DEATH(1)

Before 1816, physicians were not well trusted in their ability to diagnose death. Fear of being buried alive was pervasive. In ancient Rome, they would call out the deceased person’s name three times. If the person did not respond, then a finger would be amputated; if the site did not bleed then the deceased would be cremated. In the 14th century, the Duke of Lancaster was so fearful that he would be buried alive that he left instructions for his executors that he was to lie in his bed for 40 days. If, at the end of that time, the doctors still believed he was dead, then he would be buried. In 1790, the words “I am dead” were written on mirrors in “invisible ink” (silver nitrate) and, as the body decomposed it produced hydrogen sulfide, and the writing became visible as silver sulfide was produced. In 1897, a coffin was patented that alerted the living that someone was buried alive: if the presumed deceased awoke from sleep beneath the ground after death was misdiagnosed, a device was rigged to light a lantern, raise a flag, and ring a bell. In the 19th century, a French physician won an academic award for designing clawed forceps that were designed to clamp around the nipple of the presumed corpse to confirm death. If the patient did not respond, he or she could be declared dead. England’s most famous playwright,William Shakespeare, investigated definitions of death more than once in his life. In arguably his most famous play, Romeo and Juliet, Romeo’s misdiagnosis of Juliet’s death sealed the categorization of the great play as a tragedy. In King Lear, we learn about some of the tools that they used in diagnosing death: Ridden with guilt and holding his dead daughter, Cordelia, in his arms the King states:  “… I know when one is dead, and when one lives. She’s dead as earth. Lend me a looking glass. If that her breath will mist or stain the stone, why then she lives.” - Act V, Scene III

With the invention of the stethoscope in 1816, physicians began to be trusted in their ability to diagnose death. Even after the invention of the electrocardiograph, there was no change in the use of respirations, heart sounds and pulse as the primary modes of confirming death. The relationship between a pulse and electrical activity, more than any other clinical phenomenon, is useful in the construct of death as a continuum rather than a single moment. If you leave the patient on telemetry, they will lose a pulse and have no respirations for some period of time before they will develop asystole.

For the first half of the 20th century, physicians were entrusted with the confirmation of death using cardiorespiratory criteria, and there seemed to be little reason for change. The beginning of a change started in 1952 with an outbreak of polio in Copenhagen, Denmark. During this epidemic, a 12-year-old girl underwent a tracheotomy and was placed on positive pressure ventilation rather than an iron lung.

Her breathing was assisted by bag ventilation. Medical students and other volunteers hand ventilated patients as part of their civic duty. A machine eventually replaced the medical students and was colloquially called the “mechanical student.” It was not long after that when positive pressure ventilation began to be used for primary respiratory failure and central nervous system failure as well as neuromuscular diseases like polio. In 1957, a French physician, Pierre Mollaret, reported on patients who had developed brain injury and were on mechanical ventilation. On clinical examination, they had no brainstem reflexes and postmortem examination revealed brain liquefaction.

A NEW DIAGNOSIS OF DEATH

In 1967, Thomas Starzl performed the first human-to-human liver transplant in the United States using the liver of a person who was pronounced dead using cardiorespiratory criteria, and in South Africa, Christian Barnard transplanted a heart from human-to-human. The donor was a woman involved in a motor vehicle accident, and her injuries could not sustain her circulation. She was pronounced dead using cardiorespiratory criteria. Her heart was then procured. It was obvious at that time that controlled removal of organs with perfusion would be better than waiting for cardiorespiratory death.

In 1968, the Harvard Brain Death Committee published their seminal report on how to diagnose death with new criteria. Again, the history behind this manuscript is telling. The lead author, Henry Beecher, wrote a letter to the Dean of the Harvard Medical School declaring that the time had come to create new criteria for death. He said that both he and Joseph Murray felt this was necessary given the patients that were dying in need of organ transplantation. Dr. Murray, considered by many to be the father of transplantation, performed the first successful kidney transplant between twins. The Harvard Brain Death Committee’s criteria proposed that patients could have no brainstem or spinal cord reflexes. A confirmatory test was also required. Since that time we have drawn a line between the spinal cord and the brain stem, and spinal cord reflexes are allowed. The committee also required an electroencephalogram (EEG) as a confirmatory test. We often claim we have confirmed whole-brain death in the United States, but in fact we don’t require diabetes insipidus to be present, meaning the posterior pituitary is still functioning. What we do look for, and can diagnose clinically, is brainstem death. Indeed, a confirmatory test is no longer required, and there may well be some detectable EEG activity after clinically determined brain death in many cases. I believe, in Western society, we associate breathing with life, and “brain death” has achieved its high degree of acceptance in such a short time in part because of the fact that once we remove organ support, breathing ceases. That is why I doubt Western society will ever accept a persistent vegetative state as equivalent to death since, although the patient may not have consciousness, breathing can occur spontaneously.

MAKING THE DIAGNOSIS(2)

Table 1 lists the criteria used to diagnose death that are generally accepted in most jurisdictions in the United States. For example, in New York State, two exams six hours apart (with no confirmatory test) or two exams four hours apart with a confirmatory test in between are required. Table 2 lists the confirmatory tests.

TIMING OF DEATH

Confusion often arises in the intensive care unit (ICU) when a time is chosen to confirm death. Nurses frequently record asystolic telemetry strips that are timed, and this hour and minute are used as the time of death. Although there is no harm in this practice, it is important that physicians realize that the declaration of death is not an attempt to figure out the exact time of death, but to confirm that death has occurred. The recorded time should be the hour and minute the exam is completed whether neurologic or cardiorespiratory criteria are used.

PHILOSOPHY

There are two fundamental philosophical approaches to the meaning of death. The first is an epistemological approach: by what criteria are we certain death has occurred? This question can be answered by the physician once society has agreed on the basic principles. The second approach is metaphysical: what is death? This question is more fundamental but less practical. Perhaps Richard Selzer put it best when he described the progressive fragmentation of the dying body as “outposts where clusters of cells yet shine, besieged, little lights blinking in the advancing darkness. Doomed soldiers, they battle on, until Death has secured the premises all to itself.”