Brain death is a legal definition of death that emerged in the 1960s as a response to the ability to resuscitate individuals and mechanically keep the heart and lungs working. In simple terms, brain death is the irreversible end of all brain activity (including involuntary activity necessary to sustain life) due to total necrosis of the cerebral neurons following loss of blood flow and oxygenation. Necrosis (in Greek Νεκρός = "dead" is the name given to unnatural Death of cells and living tissue. Neurons (ˈnjuːɹɒn also known as neurones and nerve cells) are responsive cells in the Nervous system that process and transmit information Blood flow is the flow of Blood in the Cardiovascular system. Oxygenation refers to the amount of Oxygen in a medium In Blood it may be taken to be synonymous with Saturation, which describes the degree to which It should not be confused with a persistent vegetative state. A persistent vegetative state (PVS is a condition of patients with severe Brain damage in whom Coma has progressed to a state of wakefulness without detectable

Contents 1 Legal history 1.1 Religion 2 Medical criteria 3 Consciousness 4 Organ donation 5 See also 6 References 7 External links

Legal history

Traditionally, both the legal and medical communities determined death through the end of certain bodily functions, especially respiration and heartbeat. Death is the termination of the biological functions that define living Organisms It refers both to a specific With regard to living things, a body is the integral physical material of an individual In Animal physiology, respiration is the transport of Oxygen from the outside air to the cells within tissues and the transport of Carbon dioxide Measuring heart rate The Pulse rate (which in most people is identical to the heart rate can be measured at any point on the body where an Artery 's pulsation With the increasing ability of the medical community to resuscitate people with no heart beat, respiration or other signs of life, the need for a better definition of death became obvious. This need gained greater urgency with the widespread use of life support equipment, which can maintain body functions indefinitely, as well as rising capabilities and demand for organ transplantation. Life support, in the medical field refers to a set of therapies for preserving a patient's life when essential body systems are not functioning sufficiently to sustain life unaided

In the U. S. , an ad hoc committee at Harvard Medical School published a pivotal 1968 report to define irreversible coma. Harvard Medical School ( HMS) is one of the graduate schools of Harvard University and currently the #1 medical school in America as ranked by U In Medicine, a coma (from the Greek koma, meaning deep sleep is a profound state of Unconsciousness. The Harvard criteria gradually gained consensus toward what is now known as brain death. In the wake of the 1976 Karen Ann Quinlan controversy, state legislatures moved to accept brain death as an acceptable indication of death. Karen Ann Quinlan ( March 29 1954 Finally, a presidential commission issued a landmark 1981 report — Defin­ing Death: Medical, Legal, and Ethical Issues in the Determination of Death. — that rejected the "higher brain" approach to death in favor of a "whole brain" definition. This report was the basis for the Uniform Determination of Death Act, which is now the law in almost all fifty states. The Uniform Determination of Death Act ( UDDA) is a Uniform act approved in the United States in 1980 by the National Conference of Commissioners on

Today, both the legal and medical communities use "brain death" as a legal definition of death. Using brain-death criteria, the medical community can declare a person legally dead even if life support equipment keeps the body's metabolic processes working. The first nation to adopt brain death as a legal definition of death was Finland in 1971. Finland, officially the Republic of Finland ( is a Nordic country situated in the Fennoscandian region of northern Europe. In the United States, Kansas enacted a similar law earlier. The United States of America —commonly referred to as the Kansas ( is a Midwestern state in the central region of the United States of America, an area often referred to as the American " ^[1]

Religion

Despite the adoption of whole brain criteria in the United States and "brainstem" criteria in the United Kingdom, there has been opposition to brain death criteria from the beginning. Traditionalist Orthodox Jews have staunchly defended the traditional conception of death in the U. S. and Israel. ^[2] Conversely, some modern Orthodox rabbis and Israel's Chief Rabbinate have adopted determinations of death based on brain function. The Chief Rabbinate of Israel ( הרבנות הראשית לישראל) is the supreme Jewish religious governing body in the state of Israel. ^[3] As a result, Orthodox Jewish ethics has been sharply divided over key death-related policies. Jewish ethics stands at the intersection of Judaism and the Western philosophical tradition of Ethics. Tactically, Orthodox Jewish opponents to brain death have requested waivers from state law, as a matter of religious freedom, so as to continue relying on traditional indicia. ^[2][3] Meanwhile, proponents such as Halichic Organic Donor Society have been active in advocating organ donations and transplants. Organ donation is the removal of the tissues of the Human body from a person who has recently Died, or from a living donor for the purpose of transplanting

Similarly, Islamic views on brain death are mixed. ^[4][5][6]

The 1981 federal report, Defin­ing Death, found that Catholic and Protestant theologies did not object to brain death criteria. Catholic is an Adjective derived from the Greek adjective '' / 'katholikos' meaning "whole" or "complete". Protestantism refers to the forms of Christian faith and practice that originated in the 16th century Protestant Reformation. Indeed, Dennis Horan, president of the pro-life group American Citizens United for Life, stated:

Legislation limiting the concept of brain death to the irreversible cessation of total function of the brain, including the brain stem, is beneficial and does not undermine any of the values we seek to support. Overview See also Ethical aspects of abortion Pro-life individuals generally believe that human life should be valued either from conception or Implantation

More recently, the findings of the 1981 President's Commission Report have been questioned. ^[7] The new attack on brain death criteria has been multi-pronged. First, the view that brain death marks the end of the integrated unity of the human organism has been questioned. Alan Shewmon has argued that the body as a whole is the central integrator of the organism rather than the brain. ^[8] He appeals to, among other reasons, brain dead pregnant women who have lived up to 200+ days and given birth to healthy children, as well as to a brain dead boy who lived over fourteen years on a ventilator and with basic nursing support. Others have argued that there is insufficient evidence that the entire brain is dead in a brain dead individual. ^[9] Some brain dead individuals have continuing EEG activity^[10] and others maintain normal or near-normal body temperature, implying continuing hypothalamic function. ^[11]

In Catholic medical ethics, Pope Pius XII stated that death is determined by medical experts and it "does not fall within the competence of the Church. "^[12] Advocates of brain death criteria have claimed that this implies that the church is bound to support the view of the medical community on this issue. More recently, the Pontifical Academy of Science has upheld Catholic doctrine. ^[13] Nevertheless, there was some Catholic dissent on neurological criteria for death. Dissent is a sentiment or philosophy of non-agreement or Opposition to an Idea (eg ^[14] In addition, a volume consisting of essays by opponents of brain death criteria who participated in a 2005 conference at the Pontifical Academy of Sciences was published in 2006 by a publisher outside the Vatican. ^[9]

Medical criteria

A brain-dead individual has no clinical evidence of brain function upon physical examination. Physical examination or clinical examination is the process by which a Health care provider investigates the body of a Patient for signs This includes no response to pain and no cranial nerve reflexes. Pain, in the sense of physical pain, is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm Cranial nerves are Nerves that emerge directly from the Brain stem in contrast to Spinal nerves which emerge from segments of the Spinal cord. A reflex action, also known as a reflex, is an involuntary and almost instant movement in response to stimulus. Reflexes include pupillary response (fixed pupils), oculocephalic reflex, corneal reflex, no response to the caloric reflex test and no spontaneous respirations. The oculocephalic reflex is a Medical sign seen in Comatose patients in which the eyes will move opposite the direction the head is turned thus maintaining a more-or-less The corneal reflex, also known as the blink reflex, is an involuntary Blinking of the Eyelids elicited by stimulation (such as touching or a foreign body In Medicine, the caloric reflex test is a test of the Vestibulo-ocular reflex. In living organisms a respiratory system functions to allow Gas exchange.

It is important to distinguish between brain death and states that may mimic brain death (e. g. , barbiturate intoxication, alcohol intoxication, sedative overdose, hypothermia, hypoglycemia, coma or chronic vegetative states). Barbiturates are drugs that act as central nervous system Depressants and by virtue of this they produce a wide spectrum of effects from mild Sedation Intoxication is the state of being affected by one or more psychoactive drugs. In Chemistry, an alcohol is any Organic compound in which a Hydroxyl group ( - O[[hydrogen H]]) is bound to a Carbon Intoxication is the state of being affected by one or more psychoactive drugs. A sedative, or more specifically a sedative-hypnotic, is a substance that depresses the Central nervous system (CNS resulting in calmness relaxation sleepiness Hypothermia is a condition in which an organism's temperature drops below that required for normal Metabolism and bodily functions Hypoglycemia or hypoglycaemia is the medical term for a pathologic state produced by a lower than normal level of Glucose ( sugar) in the blood In Medicine, a coma (from the Greek koma, meaning deep sleep is a profound state of Unconsciousness. A persistent vegetative state (PVS is a condition of patients with severe Brain damage in whom Coma has progressed to a state of wakefulness without detectable Some comatose patients can recover, and some patients with severe irreversible neurologic dysfunction will nonetheless retain some lower brain functions such as spontaneous respiration, despite the losses of both cortex and brainstem functionality. Thus, anencephaly, in which there is no higher brain present, is generally not considered brain death, though it is certainly an irreversible condition in which it may be appropriate to withdraw life support. Anencephaly is a Cephalic disorder that results from a Neural tube defect that occurs when the cephalic (head end of the neural tube fails to close usually between

Note that brain electrical activity can stop completely, or drop to such a low level as to be undetectable with most equipment. This includes a flat EEG during deep anaesthesia or cardiac arrest. Anesthesia, or anaesthesia (see spelling differences; from Greek grc αν- an-, "without" and grc αἲσθησις A cardiac arrest, also known as cardiorespiratory arrest, cardiopulmonary arrest or circulatory arrest, is the abrupt cessation of normal circulation of However, the EEG is not required in the United States, but is considered to have confirmatory value.

The diagnosis of brain death needs to be rigorous to determine whether the condition is irreversible. Legal criteria vary, but it generally requires neurological exams by two independent physicians. The exams must show complete absence of brain function, and may include two isoelectric (flat-line) EEGs 24 hours apart. The widely-adopted Uniform Determination of Death Act in the United States attempts to standardize criteria. The United States of America —commonly referred to as the The patient should have a normal temperature and be free of drugs that can suppress brain activity if the diagnosis is to be made on EEG criteria.

Alternatively, a radionuclide cerebral blood flow scan that shows complete absence of intracranial blood flow can be used to confirm the diagnosis without performing EEGs. A radionuclide is an Atom with an unstable nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created

Consciousness

It is presumed that a permanent cessation of electrical activity indicates the end of consciousness. Consciousness has been defined loosely as a constellation of attributes of Mind such as Subjectivity, Self-awareness, Sentience, and the Those who view the neo-cortex of the brain as solely responsible for consciousness, however, argue that electrical activity there should be the only consideration when defining death. The neocortex ( Latin for "new Bark " or "new Rind " is a part of the Brain of Mammals It is the outer layer of In many cases, especially when elevated intracranial pressure prevents blood flow into the brain, the entire brain is nonfunctional; however, some injuries may affect only the neo-cortex. Intracranial pressure, ( ICP) is the pressure exerted by the Cranium on the Brain tissue Cerebrospinal fluid (CSF and the brain's circulating The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain The case of Zach Dunlap, in which a man was declared brain dead but later recovered and remembers the doctors pronouncing him dead, ^[15] questions this presumption. However, since he was declared dead only a few hours after presentation, he did not yet meet the American Academy of Neurology's brain death criteria. The American Academy of Neurology (AAN is a professional society for neurologists and neuroscientists ^[16] While Dunlap was being disconnected from life support four hours after the pronouncement, one of his cousins, Dan Coffin, who is also a nurse, found he was responsive to pain, demonstrating that he was alive, ^[17] so this example is questionable. Life support, in the medical field refers to a set of therapies for preserving a patient's life when essential body systems are not functioning sufficiently to sustain life unaided Pain, in the sense of physical pain, is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm

Organ donation

Most organ donation for organ transplantation is done in the setting of brain death. In some nations (for instance, Belgium, Brazil, Poland, Portugal and France) everyone is automatically an organ donor, although some jurisdictions (such as Singapore) allow opting out of the system. The Kingdom of Belgium is a Country in northwest Europe. It is a founding member of the European Union and hosts its headquarters as well as those |utc_offset = -2 to -4 |time_zone_DST = BRST |utc_offset_DST = -2 to -5 |cctld Poland (Polska officially the Republic of Poland Portugal, officially the Portuguese Republic (República Portuguesa is a country on the Iberian Peninsula. This article is about the country For a topic outline on this subject see List of basic France topics. Singapore Elsewhere, consent from family members or next-of-kin is required for organ donation. The non-living donor is kept on ventilator support until the organs have been surgically removed. If a brain-dead individual is not an organ donor, ventilator and drug support is discontinued and cardiac death is allowed to occur.

See also

• Brain stem death
• Clinical death
• Death
• Persistent vegetative state

References

• Lock M. Twice Dead: Organ Transplants and the Reinvention of Death. 2002, University of California Press, Berkeley, CA.
• Howsepian AA. In defense of whole-brain definitions of death. Linacre Quarterly. 1998 Nov;65(4):39-61. PMID 12199254
• Karasawa H, et al. Intracranial electroencephalographic changes in deep anesthesia. Clin Neurophysiol. 2001 Jan;112(1):25-30. PMID 11137657

External links

• Informational Portal about Brain Death
• Brain Death from the Encyclopedia of Death and Dying
• How Stuff Works - Brain Death
• Textbook section

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