Defining Death.

The American Academy of Neurology has taken an over-due stab at defining death, from US&News Report/Health:

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.

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."

The new guidelines were developed based on a review of all of the studies on brain death published between 1995 and 2009.