Avicenna Organ Transplant InstituteInternational Journal of Organ Transplantation Medicine2000-64901120100122The Concept of Death and Deceased Organ Donation55ENF LDelmoincoHarvard Medical School, Massachusetts General Hospital Transplant Center, Boston. francis_delmonico@neob.org20100122An individual who has sustained either irreversible cessation of circulatory and respiratory functions, or irreversible cessation of all functions of the entire brain, including the brainstem is dead. A person is not dead unless his brain is dead. The time-honored criteria of stoppage of the heartbeat in circulation are indicative of death only when they persist long enough for the brain to die. Brain death does not require every brain cell to be nonviable but the criteria require an irreversible loss of neurologic function of a patient interminably supported by a mechanical respirator.For death to be diagnosed by an irreversible cessation of circulation and respiration an absence of circulationshould be observed for at least two but no more than five minutes. Irreversibility is determined by a “permanent” loss of function meaning that the function will not be restored 1) because it will neither return spontaneously, nor 2) will it return as a result of medical intervention because physicians have decided not to attempt resuscitation.