A permanent cessation of all vital functions; the end of life (often called mortality). A simple concept whose actual occurrence medicine has made very difficult to define and measure. A con-census appears to be forming that death occurs when all measurable or identifiable brain functioning (electrical or any other kind) is absent for over 24 hours.
The cessation of life, traditionally indicated by lack of heartbeat and breathing, what some medical professionals now call apparent death. In recent decades, with the develop of ventilators and other technology to assist in maintaining heart and lung functions, a new definition of death has emerged: brain death, which focuses on the lack of activity in the brain. Definitions vary from state to state, however, and the specific definition controlling in a particular area is sometimes called legal death.
State of the body in which brain function ceases and heart function can be maintained only artificially; the state at which loss of brain and heart function is not reversible. In brain death, which has recently become of legal importance, normal reflexes (e.g., respiration) are absent and consciousness cannot be recovered; organs may then be removed for transplantation before the heartbeat has stopped.
The end of life. By medical definition, death generally occurs when a person has sustained irreversible cessation of circulatory and respiratory functions. When a person’s heartbeat and respiration are being maintained mechanically, death occurs when there is an irreversible cessation of all functions of the entire brain, including the brain stem. This definition of death was proposed in 1981 by the President’s Commission for the Study of Ethical Problems in Medicine and is a modification of a definition developed at Harvard Medical School in 1968. The Harvard definition described death as brain death verified by tests that detect a total unawareness of stimuli, an absence of spontaneous muscle movement or respiration, an absence of reflexes, and the cessation of electrical activity in the brain as indicated by a flat line on an electroencephalogram. Because of advances in medical technology, death can no longer be defined as it once was, the cessation of heartbeat and respiration, since these bodily functions may be artificially prolonged for a considerable time by medical technology.
Absence of vital functions. Medically, death used to be defined as permanent cessation of the heart beat. More recently emphasis has switched to brain death, defined as permanent functional death of the centers in the brainstem that control respiration and other vital reflexes. Usually two independent medical opinions are required be fore brain death is agreed, but organs such as kidneys may then legally be removed for transplantation surgery before the heart has stopped.
Permanent cessation of all vital functions, including in animals, i.e., those of the heart, lungs, and brain.
Inevitable termination of all essential processes characterizes the state of permanent demise. The traditional signs that confirm the occurrence of death involve the lasting halt of cardiac and pulmonary activities, which consistently serve as the established criteria for certifying the cessation of life. Brain death, on the other hand, denotes the irreversible discontinuation of all functions within the entire brain, encompassing the brainstem—an integral component responsible for involuntary functions like respiration.
In regular situations where individuals are not reliant on ventilators, the determination of death relies on the absence of respiration, absence of cardiac activity, and the observation of dilated, unresponsive pupils that fail to react to light.
In situations where an individual is supported by a ventilator, the assessment of brain death relies on unmistakable indications of irreversible brain damage, continuous profound unconsciousness, the absence of spontaneous breathing upon removal of ventilatory support, and the total absence of brainstem functionality.