Redefining and reversing death: what has resuscitation science taught us about death and what happens when we die? - Sam Parnia
While many concepts regarding the nature of death and hence the questions that relate to human mortality and immortality have existed for millennia, recent scientific advances have indicated that death is in fact a biological and medical process that can now be studied through the objectivity of science. Death has traditionally been defined when the heart stops beating, respiration ceases, and the brain no longer functions as a result of which a person becomes lifeless and motionless. Although it had been considered that brain cells become permanently damaged within 5-10 minutes of cessation of blood flow after death, recent evidence suggests that neurons may remain viable for longer periods of time. As neuronal cell death occurs through a combination of apoptosis, autophagocytosis and necrosis, it may be possible to manipulate these processes and slow down the rate of cell death in the brain and other vital organs following death from circulatory arrest. Thus, while philosophically it has traditionally been considered implausible to reverse death after it has taken place, medically speaking advances in the field of resuscitation science starting about 50 years ago and in particular over the past 10 years have challenged this notion. Current optimal methods include the use of hypothermia, extra-corporeal membrane oxygenation, and mechanical cardiopulmonary resuscitation, while future research indicates a possible a role for direct inhibitors of apoptosis and novel oxygen delivery methods. An unintended consequence of these discoveries aimed at developing new lifesaving measures is that science is also inadvertently expanding our knowledge of death which has major ramifications for any discussion regarding the question of what happens when we die. Millions have now been resuscitated back tens of minutes and at times hours after a period of cardiac arrest and death. For the first time in history, many people have thus gone beyond the traditional threshold of death and have come back to relive and recount their experiences.