This page was compiled by:
Dr. Noam Stadlan, Assistant Professor
Department of Neurosurgery at Rush University, Chicago
Board member, Halachic Organ Donor Society
1. What is the definition of death?
Answer: Historically, death was defined as unconsciousness coupled with irreversible cessation of breathing (respiration) and heartbeat (circulation). This definition is still very much in use today.
However, with the invention in the late 1950’s of ventilators, artificial breathing can support the heartbeat and the brain (Christopher Reeve was supported by a ventilator from the time of his accident until his death). In addition to ventilators which mimic breathing, artificial hearts and heart transplants can continue to supply oxygenated blood to the brain. The medical community has come to understand that death is not defined as those functions which can be re-instituted artificially (breathing and heartbeat), but by the irreversible cessation of the most function and the beneficiary of both breathing and blood circulation, the brain. Therefore, a more advanced understanding of death was accepted by the medical community: when the brain dies before the heart and respiration ceases, this is known as neurological death or brain-death.
Accordingly, it is misleading to call a patient “brain-dead”, since that sounds as if the patient is alive and merely suffering from a condition. The brain dead patient is dead and the medical community knows this by the fact that the brain is dead.
Click here for a Powerpoint presentation on the definition of death, in Hebrew: אתיקה רפואית ביהדות
2. What is brain death?
Answer: Brain death is the cessation of life due to the irreversible loss of critical brain function. In other words, the brain has stopped working and will never start again. Brain death can happen in two different ways: by whole brain death, and by brain-stem death.
Brain death is a clinical diagnosis. Meaning bedside exams can reveal brain-stem death. Blood flow studies are only confirmatory, not diagnostic. If a proper exam, including apnea tests weren't done, it doesn't matter what the blood flow study shows. Also, one blood flow study is only one snapshot, not an absence of flow over a long period. If there were two studies over a period of time, both showing no blood flow, it would be confirmatory of brain-stem death.
3. What is whole brain death?
Answer: The brain mainly consists of the larger part of the brain (the cortex) and the smaller part of the brain (the brain-stem). Whole brain death is when the entire brain (both cortex and brain-stem) is not functioning, and medical tests show this to be irreversible.
4. What is brain-stem death?
Answer: This is where the lower part of the brain, called the brain-stem, is not functioning and has no chance of ever functioning again. The brain-stem has many crucial functions, including the reticular activating system, an area responsible for activating and deactivating the rest of the brain. As a result of brain-stem death, none of the brain (including the cortex) will show any external evidence of working. The brain-stem also controls breathing, so that a person whose brain-stem isn’t working cannot breathe at all on their own. He or she is unconscious and the beating heart is totally dependent on getting oxygen from a ventilator.
5. What is the difference between whole brain death and brain-stem death (BSD)?
Answer: In both cases, there is a total absence of any response whatsoever to stimulation, and a total lack of breathing and total unconsciousness and no chance of recovery. The difference lies in the results of testing. In BSD there are instances where blood succeeds in reaching other areas of the cortex and there can be measurable electrical tracings as indicated by an EEG. This is not necessarily indicative of brain function but rather that some cells have electrical activity. Very much like a heart that stops beating has cells that that have electrical activity. Even with this activity, if the patient is brain-stem dead, there is no chance of recovering consciousness or breathing.
6. Can a person wake up from brain-stem death?
Answer: No. No patient that was ever diagnosed brain-stem dead by adequate criteria (Clinical bedside testing, Apnea, and Brain Blood Flow Studies) has ever woken up from brain-stem death. Brain-stem death, according to the medical community, is death. And even though the heart now continues to beat because it is artificially being supplied with oxygen (by means of ventilator), ultimately there will be complete systemic failure and the heart will stop beating, usually within a few days.
The first step is to establish that a competent cause of brain-stem death exists. In other words, just because someone is unconscious, we don’t suspect that they are whole-brain or brain-stem dead. There has to be significant injury (trauma, stroke, swelling, etc.) to the brain that makes one suspect death by neurologic criteria. Sometimes, when the medical history is unclear, imaging studies, such as CT or MRI, are able to supply evidence that a trauma has occurred to the brain. In addition, reversible causes of deep coma, such as hypothermia (low body temperature), hypotension (low blood pressure), overdose of certain drugs (such as barbiturates, paralytics, etc.), and a small group of neurological conditions, must be ruled out.
Next is the physical examination of the patient. First and foremost, the patient must be unconscious in a very deep coma state, unresponsive to any stimulation, and not breathing on his or her own. In other words, there can be no response of any kind to voice, pain, or any stimulation. If there is any response, the patient by definition is not brain-stem dead.
The specific functions of the brain-stem are tested for even the slightest function. This means looking for reflexes whose pathways run through the brain-stem. If any of the reflexes are present, it means that those pathways still work, and at least part of the brain-stem is alive. Of the many neurological reflexes of the brain-stem, the 6 main reflexes are:
9. What is Confirmatory testing?
Answer: In addition to observing lack of neurological reflexes controlled by the brain-stem, (e.g. lack of breathing), there are a number of tests available to help assess brain function.
Imaging - CT and MRI scans are able to show the brain and see if any damage (e.g. trauma, bleeding, and swelling) is evident. If it is not, the diagnosis of brain death is doubtful.
EEG (Electroencephalogram) – The EEG measures the activity of brain cells. In some cases of brain-stem death, some electrical activity is sometimes seen in areas of the brain outside the brain-stem. In whole brain death, the EEG is totally silent. Other tests, such as brain-stem audio-evoked responses (BAER) measure the electrical activity of a specific pathway. The BAER measures how the brain responds to sound. In both brain-stem death and whole brain death, the BAER should show the absence of any response from the brain and the brain-stem.
Brain Blood Flow Studies – Brain Blood Flow studies document the presence or absence of blood flow to the brain:
10. How is whole brain death determined?
Answer: The findings on examination in whole brain death are the same as in brain-stem death (no breathing, no reflexes, deep coma, etc.). The only difference is that the confirmatory studies (EEG, blood flow, etc.) show that there is no function or blood flow to any part of the brain.
11. What does an autopsy of a dead patient by neurological criteria show?
Answer: Examinations (at autopsy) of the brains of patients who have been declared brain-dead, even whole-brain-dead, do not always show that every single brain cell was dead. This does not mean that the brain was capable of functioning or that those cells were capable of function. Even people declared dead based on cardiac criteria, show evidence of cellular life in the cells of the heart for a short time even after the beating of the heart has stopped. This does not mean the heart or the person was “alive.”
12. Can any doctor declare a patient to be brain dead?
Answer: Criteria differ from state to state, and hospital to hospital. Although any physician can legally make this declaration, it is best done by a Neurologist or Neurosurgeon or by a physician who is very familiar with the protocols and proper means of testing, in order ensure that a patient who appears brain dead is actually brain dead.
13. What are the chances of a doctor misdiagnosing brain death?
Answer: People express concern that doctors will make a mistake in their diagnosis of brain death. Yet there are many more mistakes that doctors make diagnosing clinical death (the irreversible cessation of heartbeat) than mistaking brain death. One of the reasons is because any doctor who recently graduated medical school is allowed to declare cardiac death. But only a specialist (a neurologist) - who has many years of experience - is allowed to declare brain death.
14. What is the difference between coma and brain-death? (Are all patients in a coma also brain dead?)
Answer: Brain death is quite rare. Patients can be in a coma or have severe brain damage but still have some brain function and not be brain dead. Most patients in a coma are not brain dead, and they sometimes recover. Patients who are brain dead (whole brain dead and brain-stem dead), on the other hand, have no chance of recovery.
15. What is persistent vegetative state (PVS)?
Answer: PVS is a type of coma. A PVS patient is not dead according to American law or Israeli law. PVS describes severe brain damage where the patient is unconscious and does not respond significantly to most stimulation. The unconscious patient sometimes responds to some pain and has some reflexes, but does not respond to voice and does not communicate. Most often PVS patients are breathing on their own. The diagnosis of PVS is given only after this medical situation has persisted for a period of months.
There have been rare cases where PVS patients have regained consciousness. Persistent vegetative state differs from whole brain-death in that patients who are brain dead have absolutely no observable function or reflexes of the do not breathe autonomously, and have no chance of recovery.
16. Will doctors refrain from administering full medical care if they know a patient has a signed organ donor card?
Answer: Some people believe that if doctors know you have a donor card they will prematurely declare you dead before you really are dead in order to get your organs. First, it is difficult to imagine that a doctor in good conscience would kill one patient in order to save another. Such action is unethical and illegal, exposing the physician and the hospital to criminal and civil liability. Second, most hospitals have established protocol that demands a separate medical team -– a team that was not taking care of the patient and is unaware that the patient is a potential donor -– to determine if the patient is brain-stem dead or not.
Answer: With all organs - except kidneys - the transplant community always knows who will be getting which organs before the removal of the organs from the donor. Sometimes that changes when the surgeon sees the organ or as a result of tests done in the OR, or maybe even the potential recipient’s status changes. If an appropriate recipient is not found, the organ is not removed.
Answer: People 60-64 are likely to live 4.8 more years on dialysis vs 13 more years on dialysis (that is 8-9 years longer) for 45-50 year-olds. The benefit is 13-14 more years on transplant than on dialysis -- and these increments do not even take into account concurrent illness or how long the person had been on dialysis prior to transplantation.
Answer: Pregnant women who became brain dead can carry for a fetus a few weeks or more. So while the body of a brain dead woman can continue to be pregnant and successfully gestate a baby, does that mean she is "alive?" The question is what function or tissue is the essence of a human being? Modern science is good enough that we can support these bodily functions without a functioning brain. But does that mean if we build an incubator that can allow a zygote to gestate that we assign it the status of a human being?
Answer: There have not been any documented responses suggesting awareness of pain in people who are brain dead and it makes no physiological sense since the nerves mediating pain pass through the (now destroyed) brain stem to transmit their signals. There have been reports of increases in blood pressure with skin incisions for organ procurement. These increases in blood pressure are eliminated with sympathetic blockers, and are not eliminated with narcotics, proving that it is a spinal sympathetic reflex, not a pain mediated response. The mass flexion response (sitting up) is well documented as a spinal reflex (reflex of Ivan) and has nothing to do with brain function.