Suspended animation

Suspended animation is the temporary (short- or long-term) slowing or stopping of biological function so that physiological capabilities are preserved. It may be either hypometabolic or ametabolic in nature. It may be induced by either endogenous, natural or artificial biological, chemical or physical means. In its natural form it may be spontaneously reversible as in the case of species demonstrating hypometabolic states of hibernation or require technologically mediated revival when applied with therapeutic intent in the medical setting as in the case of deep hypothermic circulatory arrest (DHCA).[1][2]

For other uses, see Suspended animation (disambiguation).

Cardiopulmonary resuscitation (CPR) being performed on a trauma patient in a hospital of Maracay, Venezuela. Like CPR, suspended animation could delay the onset of cell death (necrosis) in seriously injured or ill patients, providing them with more time to receive definitive medical treatment.

Basic principles
Hazel dormouse (Muscardinus avellanarius) preparing for hibernation, nearly doubling its body weight. Bonn, Zoological Research Institute and Museum.

Suspended animation has been understood as the slowing or stopping of life processes by exogenous or endogenous means without terminating life itself.[3] Breathing, heartbeat and other involuntary functions may still occur, but they can only be detected by artificial means.[4] For this reason, this procedure has been associated with a lethargic state in nature when animals or plants appear, over a period, to be dead but then can wake up or prevail without suffering any harm. This has been termed in different contexts hibernation, dormancy or anabiosis (this last in some aquatic invertebrates and plants in scarcity conditions). In July 2020, marine biologists reported that aerobic microorganisms (mainly), in "quasi-suspended animation", were found in organically-poor sediments, up to 101.5 million years old, 250 feet below the seafloor in the South Pacific Gyre (SPG) ("the deadest spot in the ocean"), and could be the longest-living life forms ever found.[5][6]

This condition of apparent death or interruption of vital signs may be similar to a medical interpretation of suspended animation. It is only possible to recover signs of life if the brain and other vital organs suffer no cell deterioration, necrosis or molecular death principally caused by oxygen deprivation or excess temperature (especially high temperature).[7]

Some examples of people that have returned from this apparent interruption of life lasting over half an hour, two hours, eight hours or more while adhering to these specific conditions for oxygen and temperature have been reported and analysed in depth, but these cases are not considered scientifically valid. The brain begins to die after five minutes without oxygen; nervous tissues die intermediately when a "somatic death" occurs while muscles die over one to two hours following this last condition.[8]

It has been possible to obtain a successful resuscitation and recover life in some instances, including after anaesthesia, heat stroke, electrocution, narcotic poisoning, heart attack or cardiac arrest, shock, newborn infants, cerebral concussion, or cholera.

Supposedly, in suspended animation, a person technically would not die, as long as he or she were able to preserve the minimum conditions in an environment extremely close to death and return to a normal living state. An example of such a case is Anna Bågenholm, a Swedish radiologist who allegedly survived 40 minutes under ice in a frozen lake in a state of cardiac arrest with no brain damage in 1999.[9]

Other cases of hypothermia where people survived without damage are:

  • John Smith, a 14-year-old boy who survived 15 minutes under ice in a frozen lake before paramedics arrived to pull him onto dry land and saved him.[10]
  • Mitsutaka Uchikoshi, a Japanese man who survived the cold for 24 days in 2006 without food or water when he fell into a state similar to hibernation[11]
  • Paulie Hynek, who, at age two, survived several hours of hypothermia-induced cardiac arrest and whose body temperature reached 64 °F (18 °C)[12]
  • Erika Nordby, a toddler who in 2001 was revived after two hours without apparent heartbeat with a body temperature of about 61 °F (16 °C)[13]

Human hibernation
The American toad (Anaxyrus americanus) is an amphibian that can hibernate in winter.

Since the 1970s, induced hypothermia has been performed for some open-heart surgeries as an alternative to heart-lung machines. Hypothermia, however, provides only a limited amount of time in which to operate and there is a risk of tissue and brain damage for prolonged periods.

There are many research projects currently investigating how to achieve "induced hibernation" in humans.[14][15] This ability to hibernate humans would be useful for a number of reasons, such as saving the lives of seriously ill or injured people by temporarily putting them in a state of hibernation until treatment can be given.

The primary focus of research for human hibernation is to reach a state of torpor, defined as a gradual physiological inhibition to reduce oxygen demand and obtain energy conservation by hypometabolic behaviors altering biochemical processes. In previous studies, it was demonstrated that physiological and biochemical events could inhibit endogenous thermoregulation before the onset of hypothermia in a challenging process known as "estivation". This is indispensable to survive harsh environmental conditions, as seen in some amphibians and reptiles.[16]

Scientific possibilities

Temperature-induced

Lowering the temperature of a substance reduces chemical activity by the Arrhenius equation. This includes life processes such as metabolism.

Hypothermic range

In June 2005, scientists at the University of Pittsburgh's Safar Center for Resuscitation Research announced they had managed to place dogs in suspended animation and bring them back to life, most of them without brain damage, by draining the blood out of the dogs' bodies and injecting a low temperature solution into their circulatory systems, which in turn keeps the bodies alive in stasis. After three hours of being clinically dead, the dogs' blood was returned to their circulatory systems, and the animals were revived by delivering an electric shock to their hearts. The heart started pumping the blood around the body, and the dogs were brought back to life.[17]

On 20 January 2006, doctors from the Massachusetts General Hospital in Boston announced they had placed pigs in suspended animation with a similar technique. The pigs were anaesthetized and major blood loss was induced, along with simulated - via scalpel - severe injuries (e.g. a punctured aorta as might happen in a car accident or shooting). After the pigs lost about half their blood the remaining blood was replaced with a chilled saline solution. As the body temperature reached 10 °C (50 °F) the damaged blood vessels were repaired and the blood was returned.[18] The method was tested 200 times with a 90% success rate.[19]

Chemically induced

The laboratory of Mark Roth at the Fred Hutchinson Cancer Research Center and institutes such as Suspended Animation, Inc are trying to implement suspended animation as a medical procedure which involves the therapeutic induction to a complete and temporary systemic ischemia, directed to obtain a state of tolerance for the protection-preservation of the entire organism, this during a circulatory collapse "only by a limited period of one hour". The purpose to avoid a serious injury, risk of brain damage or death, until the patient reaches specialized attention.[20]

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See also

References
  1. "Suspended Animation". Medical-Dictionary.thefreedictionary.com.
  2. Asfar, P; Calzia, E; Radermacher, P (2014). "Is pharmacological, H2S-induced 'suspended animation' feasible in the ICU?". Crit Care. 18 (2): 215. doi:10.1186/cc13782. PMC 4060059. PMID 25028804.
  3. Asfar, P. (2014). "Is pharmacological, H2S-induced 'suspended animation' feasible in the ICU?". Critical Care. 182 (2): 215. doi:10.1186/cc13782. PMC 4060059. PMID 25028804.
  4. "How do frogs survive winter? Why don't they freeze to death?". Scientific American. 11 July 2014. Retrieved 3 June 2017.
  5. Wu, Katherine J. (28 July 2020). "These Microbes May Have Survived 100 Million Years Beneath the Seafloor - Rescued from their cold, cramped and nutrient-poor homes, the bacteria awoke in the lab and grew". Retrieved 31 July 2020.
  6. Morono, Yuki; et al. (28 July 2020). "Aerobic microbial life persists in oxic marine sediment as old as 101.5 million years". Nature Communications. 11 (3626). Retrieved 31 July 2020.
  7. ":Molecular death is". Forensic Medicine_gradestack.com. Cite journal requires |journal= (help)
  8. "Definition of suspended animation is". Forensic Medicine_gradestack.com. Cite journal requires |journal= (help)
  9. "'Miracle' student survived his body being frozen solid". independent.co.uk. 20 January 2016. Retrieved 5 June 2017.
  10. Suspended Animation? How A Boy Survived 15 Minutes Trapped Under Ice In Frozen Lake at Medical Daily
  11. Japanese man in mystery survival at BBC News
  12. Eleva boy’s story part of national tour to honor Mayo Clinics 150 years Archived 11 May 2015 at the Wayback Machine Mayo Clinic
  13. Warick, Jason (23 February 2002). "'Miracle child' bears few scars one year after brush with death". Edmonton Journal. p. A3.
  14. New Hibernation Technique might work on humans | LiveScience at www.livescience.com
  15. Race to be first to 'hibernate' human beings - Times Online at www.timesonline.co.uk
  16. "Is Human Hibernation Possible?" (PDF). nature.berkeley.edu. Cite journal requires |journal= (help)
  17. Mihm, Stephen (11 December 2005). "Zombie Dogs". The New York Times.
  18. Alam HB, Rhee P, Honma K, Chen H, Ayuste EC, Lin T, Toruno K, Mehrani T, Engel C, Chen Z. (2006). "Does the rate of rewarming from profound hypothermic arrest influence the outcome in a swine model of lethal hemorrhage?". J Trauma. 60 (1): 134–146. doi:10.1097/01.ta.0000198469.95292.ec. PMID 16456447.CS1 maint: uses authors parameter (link)
  19. "Doctors claim suspended animation success". The Sydney Morning Herald. 20 January 2006. Retrieved 10 October 2006.
  20. Bellamy, R; Safar, P; Tisherman, S. A; Basford, R; Bruttig, S. P; Capone, A; Dubick, M. A; Ernster, L; Hattler Jr, B. G; Hochachka, P; Klain, M; Kochanek, P. M; Kofke, W. A; Lancaster, J. R; McGowan Jr, F. X; Oeltgen, P. R; Severinghaus, J. W; Taylor, M. J; Zar, H (1996). "Suspended animation for delayed resuscitation. Crit Care Med. 1996 Feb;24(2 Suppl):S24-47". Critical Care Medicine. 24 (2 Suppl): S24–47. doi:10.1097/00003246-199602000-00046. PMID 8608704.

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