Brain Death

 
Despite the advances in medical technology and the efforts of the healthcare team, physicians and healthcare providers will not always be able to save a patient’s life. This is the case when an injury to the brain makes it impossible for the patient to breathe or the heart to beat without life support equipment.
 
The following is designed to help families who have been told by an intensive care unit (ICU) doctor (known as an intensivist) that a family member or loved one has experienced brain death. Brain death, or more formally death by neurologic criteria, is a medical diagnosis and is recognized legally.
 
What does death by neurological criteria or brain death mean?
 
Breathing and heart beats are complex functions controlled by many areas of the brain, including a tiny part about the size of the thumb called the brain stem. Traditionally, death has been defined as the irreversible loss of vital functions, such as breathing and heartbeat. Injury to the brain stem and the diagnosis of brain death means there is no possibility for a recovery. These patients cannot breathe and maintain a heartbeat without mechanical help. If no breathing machine is used to support the patient’s breathing, or no intravenous medications are given to maintain the patient’s blood pressure, the heartbeat and breathing will stop. No thinking occurs when the patient’s brain stops working, even if artificial breaths are being given by the machine and the heart is still beating. Without artificial and mechanical support, the natural course in these patients is that all body functions will continue to deteriorate and stop.
 
Following a diagnosis of brain death, the patient’s organs (the heart, lungs, kidneys, and liver, among others) can be supported by artificial interventions if the organs are to be transplanted. The only reason to continue organ-supporting measures is to determine whether the patient wanted to be an organ donor. The supportive measures are only possible in the ICU environment.
 
Preparation for organ transplantation is the only reason that physicians are obliged to keep the brain dead patient’s heart beating through the use of the breathing machine. Continuing for other reasons is considered medically inappropriate and against medical ethics. Likewise, further invasive procedures, such as placement of a feeding tube, are inappropriate.
 
What can cause death by neurological criteria (brain death)?
 
Causes of catastrophic and irreversible damage of the entire brain, including the brain stem, can include:
 
• Traumatic brain injuries caused by motor vehicle accidents, violence, and falls

• Lack of oxygen to the brain tissue for an extended period, usually after a prolonged stop in the actions of the heart or lungs, possibly caused by a drug overdose or shock

• Brain tumors, infections, massive strokes, or bleeding into the brain, leading to severe swelling of the brain
 
What is the legal definition of death in the Uniform Determination of Death Act, and why is this definition needed?
 
In the United States and its jurisdictions, a patient can be pronounced dead by either of two standards as defined by the Uniform Determination of Death Act (UDDA):

• On the basis of cardiac criteria, which means that the heart has stopped, or

• On the basis of neurological criteria (brain death), when irreversible loss of brain function, including brain stem activity, occurs.
 
Once a person is declared dead on the basis of neurological criteria, all medical interventions are discontinued. The time of death is when the physician determines death on the basis of neurological criteria, not when the heartbeat stopped after discontinuation of support; these patients are dead, even if the heart is still beating, because brain function has stopped. If the patient wished to be an organ donor, the breathing machine may be left on until the body is moved to the operating room. Otherwise, the body is transported to a morgue or to a funeral home. A licensed physician or coroner will issue a death certificate—which includes the time, place, and cause of death—at a later date.
 
Who determines death on the basis of neurological criteria (brain death)?
 
Every hospital or jurisdiction has adopted a vigorous series of actions, or protocol, to determine death by neurological criteria. The brain death exam is performed by two physicians examining the patient independently on two separate occasions. Physicians take the final determination very seriously and do not make a decision unless they are confident about it. Although it is not required by law, many hospitals require at least one of the two physicians to be a neurologist or neurosurgeon (a doctor with special expertise and training in diagnosing and treating brain disorders) or an intensivist. This illustrates the high level of care applied to ensure the determination of death is made correctly 100% of the time. To avoid all potential conflicts of interests, neither of the examining physicians can be caring for a patient in need of an organ transplant.
 
How do physicians determine death on the basis of neurological criteria (brain death)?
 
To be declared dead on the basis of neurological criteria, the patient should show clear-cut signs indicating:
 
• Irreversible coma or lack of awareness and arousal, and complete lack of responses to even the most painful stimulation. No purposeful eye opening, no withdrawal of a limb, and no signs of pain can be seen.
 
• Absence of reflexes arising from the brain stem, such as cough and gag. Some patients may have movements of the the arms or legs in response to
nerve stimulation, but these reflexes arise from the spinal cord, not from the brain or brain stem.
 
• Absence of natural breathing or even attempts to breathe. This is confirmed by an apnea test, in which the patient is observed closely after the breathing machine is stopped. If the patient makes no effort to breathe, the diagnosis is death on the basis of neurological criteria. Additional tests may be required if testing cannot be reliably performed or evaluated. A check for circulating blood in the brain might be done, perhaps using a brain x-ray or brain scan. A tracing of brain waves with an electroencephalogram (EEG) can be done to see if there is any electrical activity in the brain.
 
What does death by neurological criteria (brain death) mean for organ donation?
 
As mentioned earlier, a patient who has been declared dead on the basis of neurological criteria may still have a beating heart. This allows the ICU team to maintain blood flow to organs for transplantation if the patient had an advance directive for organ donation or, in the absence of a directive, if this is the family’s wish.
 
Resources
www.myicucare.org/Adult-Support: Life Support Choices, from the Society of Critical Care Medicine’s Patient and Family Support Committee
www.sccm.org/Communications/Critical-Connections/Archives: 2009 article, Organ Donation—Critical Questions
www.sccm.org/Communications/Critical-Connections/Archives: 2011 article, Renal Transplant—Procedures and Complications
www.aan.com/guidelines: American Academy of Neurology guidelines for Brain Injury and Brain Death
www.unos.org: information on organ donation and transplantation from the United Network for Organ Sharing
www.organdonor.gov: US Department of Health and Human Services’ information on organ donation
www.inspireccm.org: Institute for Public Informing of Research and Education in Critical Care Medicine
www.uniformlaws.org: full text and summary of Uniform Determination of Death Act by the National Conference of Commissioners on Uniform State Laws