Explanation of Brain Death
[6 minutes 8 seconds]
TRANSCRIPTION OF VIDEO
Hello, I’m Dr. Paul Ratzker and I have been a practicing neurosurgeon for over twenty years. Over the next five minutes I will try to explain what brain-stem death is.
Brain-stem death, sometimes called “brain death” or “neurological death,” is a term usually not well-understood by the public. People tend to confuse brain-stem death with coma. This brief animation will help explain what brain-stem death is and how it is substantially different from coma.
Let us start by understanding anatomy. The brain consists of two parts – the cortex and the brain-stem. The cortex is the larger part of the brain, the brain-stem the smaller which is actually the top of the spinal cord. The cortex controls higher functioning activities such as reading, writing, and talking.
If the cortex is seriously damaged the person might enter into a coma where he loses consciousness, but even in a coma a person might still feel pain or respond to stimuli and sometimes a comatose patient might regain consciousness.
Brain-stem death, however, is substantially different from coma. Brain-stem death is a term used to describe the whole brain dying – both the cortex and the brain-stem. The brain-stem is the central nervous system of the human body and it is the center of consciousness. If the brain-stem dies, respiration will stop. Once the heart stops receiving oxygen it too will die and stop beating and all other organs also die as a result of oxygen deprivation.
How do we know if the brain-stem has died? Modern medicine has several ways to determine that the brain-stem has died.
One way is to use imaging technology to see if there is any blood flow to the brain. If there isn’t, the brain cells have died from lack of oxygen.
Another method is to check for the neurological activities that the brain-stem controls. If the person is not conscious, cannot breathe, cannot swallow, cannot cough and pupils cannot respond to light, – these are all signs the brain-stem is dead.
How does brain-stem death occur? If a person receives a serious blow to the head, the brain might begin to swell. Since the skull is made of hard bone it does not allow the brain to expand. Physicians can try medication to reduce the swelling, but if this does not succeed the pressure in the brain can grow greater than the pressure of the beating heart.
Once this happens, the heart can no longer successfully force oxygenated blood to the brain. With no blood supply to the brain, the whole brain dies due to the lack of oxygen.
In fact, the brain cells don’t just die; they begin a process called lysis where they begin to liquefy. This liquefaction of the brain cells makes brain-stem death irreversible. Once the brain-stem dies the person stops breathing and the heart and the rest of the organs die from oxygen deprivation.
How is it possible, then, for the heart of a brain-stem dead patient to continue beating? Where does the heart get oxygen from? If the patient had been put on a ventilator to help him breathe and afterwards his brain-stem died, even though the brain-stem is dead and the lungs no longer function, the heart continues to beat because it is artificially being supplied oxygen from the ventilator.
If the brain-stem and the rest of the brain is dead, what is instructing the heart to beat? The heart is independent of the brain. It has its own electrical system called a pacemaker found within its walls that causes it to beat. As long as the heart gets oxygen from the ventilator, the heart will continue beating for a short period of time.
The heart is simply an automatic pump and is not connected to any other organ in any meaningful way. In fact, a transplanted heart, for example, does not get connected to the brain of the recipient.
After the onset of brain-stem death, if the deceased is left on a ventilator, how long will the dead body’s heart continue to beat? The heart can beat for a few more hours, sometimes even a few weeks, but on the average, the heart will beat for about two or three days and then it dies.
Brain-stem death is death! It is irreversible and systemic failure of all organs is inevitable. No one has ever so called “woken up” from brain-stem death.
If the death of the brain-stem means the patient has died, why does the dead body feel warm to the touch and look like it’s sleeping? It’s important to recognize the difference between an organism and an organ. The human being, the organism, is dead but the organs, such as the heart, are being kept alive for a few more days giving the appearance of a sleeping person.
A brain-stem dead patient is not a person suffering from brain-stem death – he is dead! Once death has been established the question facing the family in this situation is, what to do? Should the family turn off the ventilator and bury the deceased? Or should the family keep the body on a ventilator in order to donate organs and save other people’s lives? Emotionally this is a difficult decision and every family has to do what they feel is right.
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