Brain death

[6] It is also distinct from comas as long as some brain and bodily activity and function remain, and it is also not the same as the condition locked-in syndrome.

This gained greater urgency with the widespread use of life support equipment and the rising capabilities and demand for organ transplantation.

Since the 1960s, laws governing the determination of death have been implemented in all countries that have active organ transplantation programs.

[10] An ad hoc committee at Harvard Medical School published a pivotal 1968 report to define irreversible coma.

[16] This new definition, the irreversible loss of the capacity for consciousness and for spontaneous breathing, and the essentially unchanged 1976 tests held to establish that state, have been adopted as a basis of death certification for organ transplant purposes in subsequent Codes of Practice.

"[19] In Brazil, the Federal Council of Medicine revised its regulations in 2017, including "a requirement for the patient to meet specific physiological prerequisites and for the physician to provide optimized care to the patient before starting the procedures for diagnosing brain death and to perform complementary tests, as well as the need for specific training for physicians who make this diagnosis.

The recommendations have widespread international society endorsement and can serve to guide professional societies and countries in the revision or development of protocols and procedures for determination of brain death/death by neurologic criteria, leading to greater consistency within and between countries.Natural movements also known as the Lazarus sign or Lazarus reflex can occur on a brain-dead person whose organs have been kept functioning by life support.

Brain electrical activity can stop completely, or drop to such a low level as to be undetectable with most equipment.

[22] Although in the United States a flat EEG test is not required to certify death, it is considered to have confirmatory value.

The exams must show complete and irreversible absence of brain function (brain stem function in UK),[24] and may include two isoelectric (flat-line) EEGs 24 hours apart (less in other countries where it is accepted that if the cause of the dysfunction is a clear physical trauma there is no need to wait that long to establish irreversibility).

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.

Also, a radionuclide cerebral blood flow scan that shows complete absence of intracranial blood flow must be considered with other exams – temporary swelling of the brain, particularly within the first 72 hours, can lead to a false positive test on a patient that may recover with more time.

[28] In some countries (for instance, Spain,[29] Finland, the United Kingdom,[30] Portugal, France, and by 2026 Switzerland), everyone is automatically an organ donor after diagnosis of death on legally accepted criteria, although some jurisdictions (such as Singapore, Spain, the United Kingdom, France, Czech Republic, Poland and Portugal) allow opting out of the system.