Suspended animation

Last updated

CPR (cardiopulmonary resuscitation) 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. Intrahospital CPR.jpg
CPR (cardiopulmonary resuscitation) 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.

Suspended animation is the inducement of a temporary cessation or decay of main body functions, including the brain, to a hypometabolic state in order to try to preserve its mental and physiological capabilities. [1] [2]


As a theoretical concept, it has been included in a wide range of fiction books and films but has not been implemented as a medical procedure for either short or extended time. [3]

Basic principles

Hazel-mouse, (Muscardinus avellanarius) preparing for hibernation, gaining nearly double its body weight. Bonn, Zoological Research Institute and Museum. Bonner zoologische Monographien (1975) (20367841916).jpg
Hazel-mouse, (Muscardinus avellanarius) preparing for hibernation, gaining nearly double 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. [4] Breathing, heartbeat and other involuntary functions may still occur, but they can only be detected by artificial means. [5] 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).

Hibernation Any process in which an organism enters and maintains a period of dormancy in which to pass the winter. It is characterized by narcosis and by sharp reduction in body temperature and metabolic activity and by a depression of vital signs.

Hibernation is a state of inactivity and metabolic depression in endotherms. Hibernation refers to a season of heterothermy characterized by low body temperature, slow breathing and heart rate, and low metabolic rate. It is most commonly observed during the winter months. Although traditionally reserved for "deep" hibernators such as rodents, the term has been redefined to include animals such as bears and is now applied based on active metabolic suppression rather than any absolute decline in body temperature. Many experts believe that the processes of daily torpor and hibernation form a continuum and utilize similar mechanisms. The equivalent during the summer months is aestivation.

Dormancy state of minimized physical activity of an organism

Dormancy is a period in an organism's life cycle when growth, development, and physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions. Organisms can synchronize entry to a dormant phase with their environment through predictive or consequential means. Predictive dormancy occurs when an organism enters a dormant phase before the onset of adverse conditions. For example, photoperiod and decreasing temperature are used by many plants to predict the onset of winter. Consequential dormancy occurs when organisms enter a dormant phase after adverse conditions have arisen. This is commonly found in areas with an unpredictable climate. While very sudden changes in conditions may lead to a high mortality rate among animals relying on consequential dormancy, its use can be advantageous, as organisms remain active longer and are therefore able to make greater use of available resources.

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). [6]

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. [7]

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, cholera, and voluntarily as in yogis.

Yogi practitioner of Yoga

A yogi is a practitioner of yoga. In Vedic Sanskrit, yoga means "to add", "to join", "to unite", or "to attach" in its most common literal sense, whereas in recent days, especially in the West, yoga often means only the physical exercises of hatha yoga, the asanas. The term yogi is used broadly to refer to sannyasi or practitioners of meditation in a number of Indian religions. The feminine form is yogini, but is not always used, especially in the West.

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 and survived with no brain damage in 1999. [8]

Other cases of hypothermia where people survived without damage are:

Human hibernation

American toad (Bufo americanus) is an amphibian that can hibernate in winter. American toad - Bufo americanus - 3.JPG
American toad (Bufo 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. [13] [14] 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. [15]

Scientific possibilities


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. [16]

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. [17] The method was tested 200 times with a 90% success rate. [18]

From May 2014, a team of surgeons from UPMC Presbyterian Hospital in Pittsburgh plan to try the above method in gunshot victims (or those suffering from similar traumatic injuries). The trials will be done on ten such severely wounded patients and compared with ten others in similar situation but who had no access to the above method. They currently refer to the procedure as Emergency Preservation and Resuscitation for Cardiac Arrest from trauma. [19]

Cryogenic range

This concept is speculative as well as frequently misunderstood. Human beings are unable to survive suspended animation at cryogenic (extremely cold) temperatures naturally. The limits of current technology are also insufficient to prevent loss of cellular viability. Cryonics operates under a fundamentally distinct paradigm from suspended animation in that it depends on future technology as part of its premise for working. It is not currently possible to preserve mental capacities and memories by this method and only currently to cells and microorganisms.

Suspended animation is distinct from cryonics because it does not require this "benefit of the doubt" concerning future technology. It is something that immediately and demonstrably works. The medical use of suspended animation will still require optimism that diseases can be cured.

In order to achieve suspended animation, a reliable method to prevent damage to cells would be needed. Vitrification can achieve this in the laboratory only for small amounts of tissue due to cooling and other physical limits combined with cryoprotectant toxicity. [21] There is also only limited evidence that it is possible in principle, because only very small organisms can be vitrified or frozen safely. Research on Caenorhabditis elegans has shown that memories can be recovered, and such organisms can survive vitrification with around 100% success rates. [22] [23] [24] [25]

Chemically induced

Some Research institutes like Roth Lab founded by Mark Roth have studied seriously the possibility of suspended animation, originally for chromosome isolation, and diagnosing several illnesses like cancer.

An article in the 22 April 2005 issue of the scientific journal Science reports success towards inducing suspended animation-like hypothermia in mice. The findings are significant, as mice do not hibernate in nature.

The laboratory of Mark B. Roth at the Fred Hutchinson Cancer Research Center in Seattle, Washington, placed the mice in a chamber containing 80 ppm hydrogen sulfide for a duration of 6 hours. The core body temperature of the mice dropped to 13 degrees Celsius and metabolism, as assayed by carbon dioxide production and oxygen use, decreased 10-fold. [26] They also induced hypoxia on nematode embryos and zebrafish embryos, placing them in suspended animation for hours, and then re-animating them simply by returning the oxygen to the embryos. [27]

In trauma, the Roth laboratory 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. [28]

Massachusetts General Hospital in Boston announced they had been able to hibernate mice using the same method. Their heart rate was slowed down from 500 to 200 beats per minute, respiration fell from 120 to 25 breaths per minute and body temperature dropped to 30 °C (natural: 39 °C). After 2 hours of breathing air without hydrogen sulfide the mice returned to normal. Further studies are needed to see if the gas had damaging effects on the brain, considering the effect of hydrogen sulfide on the body is similar to hydrogen cyanide; it does not slow the metabolic rate but rather inhibits the transfer of energy within the cell via ATP. [29]

Experiments on sedated sheep [30] and partially ventilated anesthetized pigs [31] have been unsuccessful, suggesting that application to large mammals may not be feasible. In any case, long term suspended animation has not been attempted.

Genetically Induced

Ongoing research is being conducted into Tardigrades to isolate the genes responsible for their metabolic transformation into a Glass like state thus fully preserving them for decades in Dry conditions.

See also

Related Research Articles


Cryonics is the low-temperature freezing of a human corpse, with the hope that resuscitation may be possible in the future. It is regarded with skepticism within the mainstream scientific community and has been characterized as quackery.

Clinical death is the medical term for cessation of blood circulation and breathing, the two necessary criteria to sustain human and many other organisms' lives. It occurs when the heart stops beating, a condition called cardiac arrest. The term is also sometimes used in resuscitation research.

Hypothermia A human body core temperature below 35.0°C

Hypothermia is reduced body temperature that happens when a body dissipates more heat than it absorbs. In humans, it is defined as a body core temperature below 35.0 °C (95.0 °F). Symptoms depend on the temperature. In mild hypothermia there is shivering and mental confusion. In moderate hypothermia shivering stops and confusion increases. In severe hypothermia, there may be paradoxical undressing, in which a person removes their clothing, as well as an increased risk of the heart stopping.

A head transplant is an experimental surgical operation involving the grafting of one organism's head onto the body of another; in many experiments the recipient's head was not removed but in others it has been. Experimentation in animals began in the early 1900s. As of 2019, no lasting successes have been achieved.

Cryobiology is the branch of biology that studies the effects of low temperatures on living things within Earth's cryosphere or in science. The word cryobiology is derived from the Greek words κρῧος [kryos], "cold", βίος [bios], "life", and λόγος [logos], "word". In practice, cryobiology is the study of biological material or systems at temperatures below normal. Materials or systems studied may include proteins, cells, tissues, organs, or whole organisms. Temperatures may range from moderately hypothermic conditions to cryogenic temperatures.

Reperfusion injury or reperfusion insult, sometimes called ischemia-reperfusion injury (IRI) or reoxygenation injury, is the tissue damage caused when blood supply returns to tissue after a period of ischemia or lack of oxygen. The absence of oxygen and nutrients from blood during the ischemic period creates a condition in which the restoration of circulation results in inflammation and oxidative damage through the induction of oxidative stress rather than restoration of normal function.

Cerebral hypoxia

Cerebral hypoxia is a form of hypoxia, specifically involving the brain; when the brain is completely deprived of oxygen, it is called cerebral anoxia. There are four categories of cerebral hypoxia; they are, in order of severity: diffuse cerebral hypoxia (DCH), focal cerebral ischemia, cerebral infarction, and global cerebral ischemia. Prolonged hypoxia induces neuronal cell death via apoptosis, resulting in a hypoxic brain injury.

James Hiram Bedford was an American psychology professor at the University of California who wrote several books on occupational counseling. He is the first person whose body was cryopreserved after legal death, and who remains preserved at the Alcor Life Extension Foundation.

Intrauterine hypoxia Human disease

Intrauterine hypoxia occurs when the fetus is deprived of an adequate supply of oxygen. It may be due to a variety of reasons such as prolapse or occlusion of the umbilical cord, placental infarction and maternal smoking. Intrauterine growth restriction (IUGR) may cause or be the result of hypoxia. Intrauterine hypoxia can cause cellular damage that occurs within the central nervous system. This results in an increased mortality rate, including an increased risk of sudden infant death syndrome (SIDS). Oxygen deprivation in the fetus and neonate have been implicated as either a primary or as a contributing risk factor in numerous neurological and neuropsychiatric disorders such as epilepsy, ADHD, eating disorders and cerebral palsy.

Deep hypothermic circulatory arrest (DHCA) is a surgical technique that involves cooling the body to temperatures between 20°C (68°F) to 25 °C (77 °F), and stopping blood circulation and brain function for up to one hour. It is used when blood circulation to the brain must be stopped because of delicate surgery within the brain, or because of surgery on large blood vessels that lead to or from the brain. DHCA is used to provide a better visual field during surgery due to the cessation of blood flow. DHCA is a form of carefully managed clinical death in which heartbeat and all brain activity cease.

Targeted temperature management (TTM) previously known as therapeutic hypothermia or protective hypothermia is an active treatment that tries to achieve and maintain a specific body temperature in a person for a specific duration of time in an effort to improve health outcomes during recovery after a period of stopped blood flow to the brain. This is done in an attempt to reduce the risk of tissue injury following lack of blood flow. Periods of poor blood flow may be due to cardiac arrest or the blockage of an artery by a clot as in the case of a stroke.

The Arctic Sun Temperature Management System is a non-invasive targeted temperature management system, a medical device used to modulate patient temperature with precision by circulating chilled water in pads directly adhered to the patient's skin. Using varying water temperatures and a sophisticated computer algorithm, a patient's body temperature can be controlled to the nearest 0.2 °C. It is produced by Medivance, Inc. of Louisville, Colorado.

Cryopreservation process where cells, whole tissues, etc. are preserved by cooling to sub-zero temperatures

Cryo-preservation or cryo-conservation is a process where organelles, cells, tissues, extracellular matrix, organs or any other biological constructs susceptible to damage caused by unregulated chemical kinetics are preserved by cooling to very low temperatures. At low enough temperatures, any enzymatic or chemical activity which might cause damage to the biological material in question is effectively stopped. Cryopreservation methods seek to reach low temperatures without causing additional damage caused by the formation of ice crystals during freezing. Traditional cryopreservation has relied on coating the material to be frozen with a class of molecules termed cryoprotectants. New methods are constantly being investigated due to the inherent toxicity of many cryoprotectants. By default it should be considered that cryopreservation alters or compromises the structure and function of cells unless it is proven otherwise for a particular cell population. Cryoconservation of animal genetic resources is the process in which animal genetic material is collected and stored with the intention of conservation of the breed.

Brain hypothermia, induced by cooling a baby to around 33 °C for three days after birth, is a treatment for hypoxic ischemic encephalopathy. It has recently been proven to be the only medical intervention which reduces brain damage, and improves an infant's chance of survival and reduced disability. Hypoxic ischemic encephalopathy has many causes and is essentially the reduction in the supply of blood or oxygen to a baby's brain before, during, or even after birth. It is a major cause of death and disability, occurring in approximately 2–3 per 1000 births and causing around 20% of all cases of cerebral palsy.

Mark Roth is an American biochemist, and director of the Roth Lab at the Fred Hutchinson Cancer Research Center. He is a professor at the University of Washington.

A hypothermia cap is a therapeutic device used to cool the human scalp. Its most prominent medical applications are in preventing or reducing alopecia in chemotherapy, and for preventing cerebral palsy in babies born with neonatal encephalopathy caused by hypoxic-ischemic encephalopathy (HIE). It can also be used to provide neuroprotection after cardiac arrest, to inhibit stroke paralysis, and as cryotherapy for migraine headaches.

Gaseous signaling molecules are gaseous molecules that are either synthesised internally (endogenously) in the organism, tissue or cell or are received by the organism, tissue or cell from outside and that are used to transmit chemical signals which induce certain physiological or biochemical changes in the organism, tissue or cell. The term is applied to, for example, oxygen, carbon dioxide, nitric oxide, carbon monoxide, hydrogen sulfide, sulfur dioxide, nitrous oxide, hydrogen cyanide, ammonia, methane, hydrogen, ethylene, etc.

Hydrogen sulfide is produced in small amounts by some cells of the mammalian body and has a number of biological signaling functions.

Emergency Preservation and Resuscitation (EPR) is an experimental medical procedure where an emergency department patient is cooled into suspended animation for an hour to prevent incipient death from ischemia, such as the blood loss following a shooting or stabbing. EPR uses hypothermia, drugs, and fluids to "buy time" for resuscitative surgery. If successful, EPR may someday be deployed in the field so that paramedics can suspend and preserve patients for transport.

Lance B. Becker is an American physician and academic, specializing in emergency medicine and treatment for cardiac arrest, currently at Northwell Health. He is the chairman of the department of emergency medicine at North Shore University Hospital, as well as chair and professor of emergency medicine at Hofstra Northwell School of Medicine.


  1. "Suspended Animation".
  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. "FROZEN IN TIME Terminally ill Brit schoolgirl, 14, wins court battle to have her body cryogenically frozen for £37k after her death in case she can be resurrected in future". 16 November 2016. Retrieved 4 June 2017.
  4. 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.
  5. "How do frogs survive winter? Why don't they freeze to death?". Scientific American. 11 July 2014. Retrieved 3 June 2017.
  6. ":Molecular death is". Forensic
  7. "Definition of suspended animation is". Forensic
  8. "'Miracle' student survived his body being frozen solid". 20 January 2016. Retrieved 5 June 2017.
  9. Suspended Animation? How A Boy Survived 15 Minutes Trapped Under Ice In Frozen Lake at Medical Daily
  10. Japanese man in mystery survival at BBC News
  11. Eleva boy’s story part of national tour to honor Mayo Clinics 150 years Archived 11 May 2015 at the Wayback Machine Mayo Clinic
  12. Warick, Jason (23 February 2002). "'Miracle child' bears few scars one year after brush with death". Edmonton Journal. p. A3.
  13. New Hibernation Technique might work on humans | LiveScience at
  14. Race to be first to 'hibernate' human beings - Times Online at
  15. "Is Human Hibernation Possible?" (PDF).
  16. Mihm, Stephen (11 December 2005). "Zombie Dogs". The New York Times.
  17. 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/ PMID   16456447.CS1 maint: Uses authors parameter (link)
  18. "Doctors claim suspended animation success". The Sydney Morning Herald. 20 January 2006. Retrieved 10 October 2006.
  19. "Left between life and death: First 'suspended animation' trials set to begin in bid to buy time for stabbing and gunshot victims".
  20. Cryonet 2008 Suspended Animation vs Cryonics
  21. Fahy, Gregory M.; Wowk, Brian (2015). Principles of Cryopreservation by Vitrification. Methods in Molecular Biology. 1257. pp. 30–33. doi:10.1007/978-1-4939-2193-5_2. ISBN   978-1-4939-2192-8. PMID   25428002.
  22. Vita-More, Barranco. "Persistence of Long-Term Memory in Vitrified and Revived C. elegans." Rejuvenation Research doi: 10.1089/rej.2014.1636
  23. "Basic principles of cryopreservation" (PDF).
  24. "Cryogenic Storage of Human Hematopoietic Progenitor Cells" (PDF).
  25. "Vitrification: Preservation of Cellular implants" (PDF).
  26. Blackstone, E.; Morrison, M.; Roth, M. (2005). "H2S induces a suspended animation-like state in mice". Science. 308 (5721): 518. CiteSeerX . doi:10.1126/science.1108581. PMID   15845845.
  27. "Oxygen deprivation causes suspended animation in the zebrafish embryo" (PDF).
  28. 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.
  29. "Gas induces 'suspended animation'". BBC News. 9 October 2006. Retrieved 10 October 2006.
  30. Haouzi P; Notet V; Chenuel B; Chalon B; Sponne I; et al. (2008). "H2S induced hypometabolism in mice is missing in sedated sheep". Respiratory Physiology & Neurobiology. 160 (1): 109–115. doi:10.1016/j.resp.2007.09.001. PMID   17980679.
  31. Li, Jia; Zhang, Gencheng; Cai, Sally; Redington, Andrew N (January 2008). "Effect of inhaled hydrogen sulfide on metabolic responses in anesthetized, paralyzed, and mechanically ventilated piglets". Pediatric Critical Care Medicine . 9 (1): 110–112. doi:10.1097/01.PCC.0000298639.08519.0C. PMID   18477923 . Retrieved 23 March 2008. (Subscription required (help)). H2S does not appear to have hypometabolic effects in ambiently cooled large mammals and conversely appears to act as a hemodynamic and metabolic stimulant.