What 'Brain-Dead' Means

Medically Reviewed by Brunilda Nazario, MD on January 03, 2014

Jan. 3, 2014 -- What does it mean when doctors say a person is brain-dead? WebMD asked critical care specialist Isaac Tawil, MD, an assistant professor at the University of New Mexico School of Medicine, and bioethicist Arthur Caplan, PhD, director of the Division of Medical Ethics at NYU Langone Medical Center.

Q. Is “brain-dead” the same as dead?

A. Yes. Many people think death happens when the heart stops beating and the lungs stop breathing, but machines can support those functions when the brain no longer can, Tawil says.

Q. Do doctors use specific criteria to confirm death in every case?

A. “Most people die not on machines,” so it’s not necessary to evaluate them for brain death, Caplan says.

“Typically, brain death starts with some sort of devastating neurologic injury,” Tawil says. “That can come in many different forms.” They include traumatic brain injury, a stroke caused by a ruptured blood vessel in the brain, or if the heart has stopped and the brain goes without oxygen and other nutrients it needs to survive for a long period of time.

Q. If a patient is on life support, doesn’t that mean he must be alive?

A. Loved ones might find it hard to comprehend that someone is dead when he still feels warm to the touch and his chest continues to rise and fall as a result of mechanical support, Tawil says.

“What they hear is ‘kind of dead,’ ‘maybe dead,’ ‘sort of dead,’ but they don’t hear ‘dead,’” Caplan says.

He and Tawil prefer not to use the term “life support” to describe the ventilator and other equipment that can maintain blood flow and breathing in a patient who’s been declared brain dead. “I use the term ‘organ support,’” Tawil says. “I think it’s somewhat deceiving to call it ‘life support.’”

Q. What makes doctors suspect that patients are brain-dead and not in a coma and alive?

A. Doctors and nurses test brain-injured patients for certain responses at least once an hour, Tawil says. Can they talk? Can they move their eyes?

Brain-stem reflexes are often the last to go, he says. These reflexes include the dilation of pupils when someone shines a light in the eyes and coughing or gagging when the vocal chords are tickled.

When there’s no evidence of higher brain function or brain-stem reflexes, and when other factors that could mimic brain death, such as drugs or low blood pressure, have been ruled out, “that’s when we’ll approach the family” and explain the need for a formal brain-death evaluation, Tawil says.

Q. How do doctors determine that a patient is brain-dead?

A. A formal brain-death evaluation takes about 20 minutes, Tawil says.

First, the doctor will check to see if the patient flinches in response to something that can cause pain, like pinching the skin. Next, the doctor will make sure that there are no brain stem reflexes. Finally, the doctor will disconnect the patient from the respirator and check to see whether rising carbon dioxide levels in the blood stimulate the brain. If none of these three findings is present, a second doctor is called to confirm brain death, Tawil says.

(At its annual meeting in 2013, the European Society of Anaesthesiology called for an international agreement on the criteria for determining brain death, such as the number of doctors needed to agree on the diagnosis, and how many and which reflexes need to be examined.)

Q. Why continue mechanical support of a patient who’s brain-dead?

A. When doctors pronounce brain death, they’ve got to be clear to the patient’s loved ones that such support is going to stop, Caplan says. Mechanical support might continue for a short period to give out-of-town relatives time to get to the hospital to say goodbye, he says.

If the family agrees to donate the patient’s organs, though, mechanical support might be needed to keep the organs usable until they’re removed.

Q. Can a person who's been declared brain-dead be revived?

A. No. Brain death is death, plain and simple.

Show Sources


Isaac Tawil, MD, assistant professor, University of New Mexico School of Medicine; director, neurosciences intensive care unit, University Hospital, Albuquerque, NM.

Arthur Caplan, PhD, director, division of medical ethics, NYU Langone Medical Center.

News release, European Society of Anaesthesiologists.

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