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Brain Trust: Even Today, Determining Brain Death is Tricky

Marcolini, Evie MD

doi: 10.1097/01.EEM.0000515680.29800.9a
Brain Trust

Dr. Marcolini is an assistant professor of emergency medicine and neurology in the department of emergency medicine and the division of neurocritical care and emergency neurology and the medical director of SkyHealth Critical Care Air Medical Transport at Yale University School of Medicine. Follow her on Twitter @eviemarcolini. Read her past columns at

brain death

brain death



The practice of medicine applies science, art, and humanism to patients of all ages. When philosophy and ethics come into play in the determination of life's beginning and end, the medical community is part of a complex and sometimes contentious conversation.

Several recent controversies have erupted in the news press about brain death, its declaration by physicians, and challenges by families or loved ones. (“Man Diagnosed as Brain Dead Recovers,” National Right to Life News; 2008;35[4]:20; Even today we lack universal agreement about whether brain death means the whole brain must be dead or when the entire brainstem is dead. (Prog Brain Res 2009;177:21.) The dead donor rule states that organ retrieval cannot cause death, but doesn't specify what constitutes death. (Hastings Cent Rep 1999;29[6]:6.) Before 1968, when medical technology discovered that patients with severe brain damage could have successful cardiopulmonary functioning, cardiac resuscitation was not widely established, and patients were declared dead only when the heart stopped. (Kennedy Inst Ethics J 1993;3[2]:113.)

The Harvard Ad Hoc Committee, recognizing that this created undue burden on patients, families, hospitals, and those who needed critical care resources, convened to clarify that brain death or irreversible coma was defined by complete unresponsiveness, absence of spontaneous respirations (apnea), no brainstem reflexes, and a flat EEG. (JAMA 1968;205[6]:337.) This definition, first described by Mollaret and Goulon in 1959, was approved by the American Bar Association and American Medical Association, and allowed for physicians to declare brain death and remove patients from ventilators legally and ethically. (Rev Neurol [Paris] 1959;101:3.)

One of the most important problems today is that the medical community is inconsistent in establishing current hospital policies for determining brain death, and consequently the accuracy of our determinations could be called into question with widespread implications for patients' and families' trust.

The medical community has an obligation to agree on a definition of brain death grounded in evidence that is universally supported and clearly communicated to the public. The American Medical Association, the American Bar Association, and the President's Commission for the Study of Ethical Problems approved the Uniform Determination of Death Act in 1981. (JAMA 1981;246[19]:2184.) This states that a patient is dead if he has irreversible cessation of circulatory and respiratory functions or irreversible cessation of all functions of the brain, including the brainstem. This was another step toward consensus, but the authors left it to the medical community to define specifically how brain death was to be determined, understanding that the standards would change with new discoveries and advances in technology.

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Criteria for Brain Death

The American Academy of Neurology provided an evidence-based guideline in 1995, updated in 2010, describing detailed criteria for brain death and procedures for testing. (Neurology 1995;45[5]:1012; Neurology 2010;74[23]:1911.) The guideline basically boils down to a four-step process:

  • Reasonable clinical evidence must explain brain death, such as a traumatic brain injury or cardiac arrest leading to anoxic brain injury. No metabolic abnormality can confound the testing, such as severe electrolyte disturbance, hypothermia, or presence of toxins.
  • The bedside clinical exam should be consistent with coma (unresponsiveness), absence of brainstem reflexes, and apnea.
  • Ancillary testing is required if any single criterion of the first two steps cannot be met; the testing can be conventional angiography, EEG, transcranial Doppler, or nuclear brain scan.
  • Documentation should include time of death, which will be the time that apnea was confirmed by arterial PCO2 reaching the target value or when the ancillary test, if necessary, was officially interpreted.

Significant variability still exists in U.S. hospital policies about how brain death is determined despite these clear guidelines. (Neurology 2008;70[4]:284.) Some require a physician; others require a nurse or physician. Some require two tests separated by time, others only one. Variability exists on locally accepted parameters for apnea testing, minimum temperature required, or time to metabolize toxins such as opioids or benzodiazepines.

As you can imagine, variability in testing could lead to inaccurate determinations and an understandable erosion of public trust. Some families are unwilling to remove the ventilator when a patient is declared brain dead, setting up an emotionally painful encounter for all involved. One survey found that only 34 percent of the public believed that brain-dead patients were legally and clinically dead. (Soc Sci Med 2004;59[11]:2325.)

It is imperative that we understand and consistently and accurately use existing brain death terminology with families, apply the evidence-based guidelines completely and accurately, and maintain vigilance to the standards. These actions will take us a long way toward standardization and accurate brain death determination. We owe it to our patients and their families to make sure we meet the highest standards in medicine when making this important determination.

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