Clinical death is the medical term for cessation of blood circulation and breathing, the two criteria necessary to sustain the lives of human beings and of many other organisms.
Without special treatment after circulation is restarted, full recovery of the brain after more than 3 minutes of clinical death at normal body temperature is rare.
[14][15] The addition of a drug treatment protocol has been reported to allow recovery of dogs after 16 minutes of clinical death at normal body temperature with no lasting brain injury.
[17] Under laboratory conditions at normal body temperature, the longest period of clinical death of a cat (after complete circulatory arrest) survived with eventual return of brain function is one hour.
[20] The prognosis is improved if clinical death is caused by hypothermia rather than occurring prior to it; in 1999, 29-year-old Swedish woman Anna Bågenholm spent 80 minutes trapped in ice and survived with a near full recovery from a 13.7 °C core body temperature.
[22][23] The purpose of cardiopulmonary resuscitation (CPR) during cardiac arrest is ideally reversal of the clinically dead state by restoration of blood circulation and breathing.
[26] In absence of cerebral function monitoring or frank return to consciousness, the neurological status of patients undergoing CPR is intrinsically uncertain.
Patients supported by methods that certainly maintain enough blood circulation and oxygenation for sustaining life during stopped heartbeat and breathing, such as cardiopulmonary bypass, are not customarily considered clinically dead.
Clinical death occurs only if machines providing sole circulatory support are turned off, leaving the patient in a state of stopped blood circulation.
Certain surgeries for cerebral aneurysms or aortic arch defects require that blood circulation be stopped while repairs are performed.
In a United States hospital, a Code Blue is declared and Advanced Cardiac Life Support procedures used to attempt to restart a normal heartbeat.
If clinical death is expected due to terminal illness or withdrawal of supportive care, often a Do Not Resuscitate (DNR) or "no code" order is in place.
[31] Conversely, in the case of Marlise Muñoz, a hospital refused to remove a brain dead woman from life support machines for nearly two months, despite her husband's requests, because she was pregnant.