Determining brain death is a complex process that requires dozens of tests to make sure doctors come to the correct conclusion.
With that goal in mind, the American Academy of Neurology has issued new guidelines — an update of guidelines first written 15 years ago — that call on doctors to conduct a lengthy examination, including following a step-by-step checklist of some 25 tests and criteria that must be met before a person can be considered brain dead.
The goal of the guidelines is to remove some of the guess work and variability among doctors in their procedure for declaring brain death, which previous research has found to be a problem, said guidelines co-author Dr. Panayiotis Varelas, director of the Neuro-Intensive Care Service at Henry Ford Hospital in Detroit.
According to the U.S. Uniform Determination of Death Act, brain death occurs when a person permanently stops breathing, the heart stops beating and "all functions of the entire brain, including the brain stem" cease.
While no one disagreed with that description, a 2008 study that included 41 of the nation's top hospitals found widespread and worrisome variability in how doctors and hospitals were determining who met the criteria, said Varelas, co-author of the 2008 review.
For example, low body temperature, or hypothermia, can cause a person to have the appearance of brain death, so bodies have to be warmed before a determination can be made, Varelas said. But hospitals in the 2008 study had 11 different "target temperatures" that varied by several degrees, and there was no consensus about what temperature was optimal to get the best diagnosis, he said.
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Those types of details have been worked out in the updated guidelines, which are published in the June 8 issue of Neurology.
"Even the best hospitals in the United States had such a tremendous variability in their policies," said Varelas. "You die either because your heart or lungs stop working, or because you become brain dead. The former two are easy to determine. If there is no pulse, you die. If there is no breathing, you die. But becoming brain dead is much more complex."
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The new guidelines were developed based on a review of all of the studies on brain death published between 1995 and 2009.
According to the guidelines, there are three major signs of brain death: coma with a known cause; absence of brain stem reflexes; and breathing has permanently stopped.
Periodically, news reports will talk about a patient in a long-term coma who miraculously woke up, or someone in a persistent vegetative state who seems to have an inner life, Varelas said. One of the best known examples was the Terri Schiavo case in Florida, which pitted the woman's parents against her husband. The 41-year-old Schiavo died in 2005, two weeks after the removal of a feeding tube that had kept her alive for more than a decade.
But brain death should not be confused with other conditions, such as persistent vegetative or minimally conscious state, in which there is still some limited brain activity.
"We found no credible report of anyone who was brain dead and who woke up and survived," Varelas said.
The new guidelines, he added, have nothing to do with those high-profile cases.
Brain death can result from a severe traumatic brain injury, stroke or lack of oxygen after cardiac arrest. About 90% of organ donations come from people who have been declared brain dead, Varelas said.
Dr. James Bernat, a professor of neurology and medicine at Dartmouth Medical School, said the new guidelines will help to remove some of the variability in how doctors determine brain death.
"The 2008 study disclosed rather surprising and disturbing variations in determining brain death, and in some cases there were practices that were just plain wrong," Bernat said.
The main risk is that a patient will be declared brain dead who really isn't, Bernat said.
"The authors of this (new) study are experts in their field and have done an evidence-based, authoritative review," Bernat said. "They are saying, 'This is the way it ought to be done.' The goal is to improve the uniformity and the quality of neurological practice."
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