Understanding Brain Death

Pennsylvania & West Virginia Death Law:
Only an individual who has sustained either: (1) irreversible cessation of circulatory and respiratory functions; or (2) irreversible cessation of all functions of the entire brain, including the brain stem, is dead. A determination of death must be made in accordance with accepted medical standards.

The American Academy of Neurology defines brain death as the irreversible loss of clinical function of the brain, including the brain stem. The Harvard Criteria for the Determination of Brain Death was established in 1968, amended in 1969 and expanded in 1981.


When trauma or disease causes devastating brain damage, brain function ceases. For brain death to be determined the patient must be observed for an adequate period of time and two standards must be met: the cause of the injury to the brain must be known, and there can be no circumstances that might make the condition reversible (such as, shock and chemical imbalance, drug intoxication, and/or low body temperature). Once these standards are met, brain death can be determined by brain stem reflex tests and apnea testing.

Brain stem reflex tests can determine brain death using several physical tests. When a patient does not react to painful stimuli nor exhibits any purposeful or spontaneous movement, brain stem dysfunction is indicated. Stimulation and irritation are used to check for the absence of gag or cough reflexes that are prominent brain stem reflexes.

Another indicator of brain stem dysfunction is the inability to breathe unassisted. An apnea test to detect spontaneous respiration is usually performed. In this situation, the ventilator is disconnected and the patient is monitored for respiratory movement for approximately 8 to 10 minutes. After blood is drawn for analysis, the ventilator is reconnected. If the blood carbon dioxide level has increased to a level to stimulate respiration and none was observed, brain death is likely.

Cerebral angiography is a photographic study of the blood flow within the brain. Without an adequate supply of blood, brain cells die from lack of oxygen. Blood flow can also be determined by ultrasound imaging and nuclear scans. An EEG is an analysis of the brain’s electrical activity, displayed as tracings on graph paper. A flat EEG indicates the absence of brain function.

The Cleveland Clinic has created a portal to provide access to the Death by Neurological Criteria (DNC) course, which explains how to properly assess evidence of cerebral function in patients in a coma. It outlines the accepted medical standards for determining DNC and details the elements included in the clinical examination. The course provides the tools to effectively diagnose a patient dead by neurological criteria. It also gives you information about how to properly discuss DNC with the families of patients.