[Part 1: 8 minutes 47 seconds]
Brain Death: Developing an Understanding
Discussions with Neurosurgeons
HODS on CNN
William Sweet, MD, D.Sc.
Massachusetts General Hospital
Peter McL. Black, MD PhD
Chief of Neurosurgery
Brigham and Women’s Hospital
Lawrence Pitts, MD
San Francisco General Hospital
Brian Andrews, MD
The diagnosis of death had always been a rather straightforward affair. (Film excerpt) Death was a condition which almost anyone could recognize. (Film excerpt) The deceased individual lay motionless and unresponsive and there were no signs of respiration or heartbeat. (Film excerpt) But times have changed. In his more than 50 years of medical practice, William Sweet, emeritus professor at Harvard has witnessed profound changes in the diagnosis of death.
Yes, originally the millennia-honored method of diagnosing death, namely when you can’t feel any heartbeat, was the criteria. Indeed when I first began in medical school we weren’t aware that it was feasible to effectively start a heart that had stopped beating. When I went over to work with the British in WWII, here I found that they were starting the stopped heart and it would go on beating, and the individual would be usefully and effectively resuscitated, revived and lead a normal life. I found that pretty astonishing just by itself. It did make clear however, that the criterion of stopping of the heart being equivalent to death was wrong. Clearly the heart is just a pump; its work is effectively handled by a mechanical pump as by the human pump. And as we scrutinized the whole problem, then, we realized that the essence of the personality in the individual is the functioning brain. And that not until the heart has stopped long enough for the brain to die is the individual dead.
Peter McL. Black:
We’re built in a very peculiar way in the sense that we need to have the brain to breathe. We don’t need to have the brain to have the heart beat. and so if you can devise a way of keeping the respiration going, keeping us breathing, then you can keep the heart going even though the brain is completely destroyed and that’s the change that occurred in the middle of the 20th century. The development of good ventilators, the development of intensive care units that allowed you to keep patients ventilated and perfused using their own hearts in situations that 20 years before would not have been possible because when the brain stopped, the patient would stop breathing, the heart would stop, and that would be the end.
And it’s only gradually that we grasped the point that it’s only when the brain is dead, that the individual is dead. Not only is there such a thing as brain death, that’s the only death there is! You’re not dead until your brain is dead.
The real impetus to think hard about this problem came with the advent of heart transplantation. In 1968, the Harvard Medical School asked Harry Beecher, the Chief of Anesthesiology of the Massachusetts General Hospital, to examine brain death. Realizing the broad medical and social implications of this issue, Beecher created a special Ad Hoc committee. The committee members represented many areas of medicine, the law, history and theology. William Sweet was a member of the committee. After months of deliberation the Ad Hoc Committee arrived at a consensus, and in August 1968 their report appeared in the journal of the American Medical Association. The report contained a set of characteristics of a permanently non-functioning brain: the so-called Harvard Criteria. Although the criteria were widely accepted by many members of the medical community, some centers found them too conservative. In the decade that followed, medical centers from around the country, and indeed from around the world, studied brain death and presented their own guidelines, over thirty different criteria in all. Part of the controversy was just how much of the brain has to be dead before the person is dead.
Peter McL. Black:
Roughly speaking there are three positions to take on the question of how much of the brain has to be gone before a patient is dead by brain criteria. One says it’s the cortex. Now the cortex is what allows us to interrelate. And you can say that then if your crucial issue is can you make relationships with other people, then cortical death is enough. Another possibility is to say that brainstem death is enough, this is what’s done in England. That what you have to show is that the brainstem isn’t functioning. In America, being the great compromisers we are, we say let’s put ‘em all together. You have to have the cortex, you have to have the brainstem and you have to show that both of those are irreversibly gone before you can make the diagnosis.
The most comprehensive examination of brain death was the collaborative study conducted by the National Institutes of Health which was completed in 1973. Nine centers from across the country studied the outcomes of 503 patients. Finally in 1981, a Presidential Commission reviewed all the existing criteria and presented a report which represented a consensus of opinions from around the nation. Lawrence Pitts was an advisor to the Commission.
They, with their large agenda, took on brain death as one of the issues, examined it carefully from a legal standpoint – – looked at the laws in the various states, looked at from a medical or technical standpoint- just how one declares brain death. And I think pulled together, I think, appropriate experts and were able to crystallize the medical issues surrounding brain death.
The criteria which emerged from the President’s Commission are now the cornerstone of most protocols. There are two key factors in the diagnosis of brain death: the loss of all cerebral and brainstem function, and irreversibility. The basis of this determination for the neurological examination of the patient.
The technical diagnosis of brain death is really a low technology, fairly straightforward neurologic examination in the main and the tools that you need for that are no more complex than one uses for a routine neurologic exam. You need a flashlight, you need a pen, you need a reflex hammer, you need a tongue blade, that’s about all you need fro the brain death examination.
The neurological examination can asses the status of both the cerebral hemispheres and the brainstem.
Specifically, functioning of the cerebral hemispheres can be assessed by evaluating the patient’s level of responsiveness. The brain dead patient has no responsivity to any stimulation including verbal stimuli or painful stimuli. Most frequently we use superorbital nerve compression to provide our painful stimuli. This avoids the possible lack of transmission of painful stimuli from the digits or the body if there’s an associated spinal cord injury.
Peter McL. Black: What we’re trying to do is to show that the brain has been destroyed. The spinal cord is not relevant to what we’re talking about and therefore the tendon reflexes which are really segmental reflex to spinal cord function are almost a priori excluded from the determination of brain death. When I’m talking about tendon reflexes, I’m not talking about posturing which is something that as a response requires part of the brain.