What is suspended animation and is it possible to introduce a person into it

What is anabiosis and why is it needed

AnabiosisAnabiosis / Big Russian Encyclopedia - This is a temporary cessation or slowdown of the vital processes of the body. Unlike hibernation (hibernation) or torpor, in this state, signs of life practically disappear.P. Asfar, E. Calzia, P. Radermacher. Is pharmacological, H2S‑induced ‘suspended animation’ feasible in the ICU? / Critical care. For example, pulse and respiration cannot be recorded without special equipment. In fact, suspended animation is death with the ability to revive.

Are capable of itAnabiosis / Big Russian Encyclopedia many organisms fall into it: protozoa, fungi, worms, crayfish, molluscs, and some insects, amphibians and reptiles. So they endureC. Hartman, b. Nussbaum, E. Calzia et al. Gaseous Mediators and Mitochondrial Function: The Future of Pharmacologically Induced Suspended Animation? / Frontiers in Physiology a sharp deterioration in living conditions, such as a cold snap or drought, and then recover.

Some organisms can remain in suspended animation for a long time. Thus, the recently discovered oceanic aerobic bacteria heldY. Morono, M. Ito, T. Hoshino et al. Aerobic microbial life persists in oxic marine sediment as old as 101.5 million years / Nature Communications in a state of suspended life from 4.3 to 101.5 million years. These organisms fell into anabiosis when dinosaurs were still roaming the Earth.

In the case of humans, anabiosis can be useful in medicine in the first place. For example, in emergency situations, when you need to save the patient's life, and traditional methods are unlikely to help.

Anabiosis is also often mentionedH. Thomson. Gunshot victims to be suspended between life and death / New Scientist as a way to save the lives of terminally ill patients before the invention of drugs or astronauts during long expeditions. However, even if scientists find a safe way to immerse a person in suspended animation for a long time, spend tens, hundreds or thousands of years in a state close to of death, is hardly possible. In such situations, hibernation with a slowdown in life processes seems to be the preferred option.

Why can't you just freeze a person

Some organisms, such as embryos, bacteria, viruses, cells, are quite easy to enter into a state of suspended animation: it is enough just to freeze them. They use itAnabiosis / Big Russian Encyclopedia biologists and physicians at creation vaccines, preservation of tissues and organs, sperm and eggs.

With people, this trick will not work - there is too much water in our body. When she freezesWITH. Amstislavsky, S. la Falza. Cryonics: myths and reality / In defense of science No. 2 (crystallizes) at sub-zero temperatures, tissues are damaged, blood flow stops, and death occurs.

A person can survive if he falls into a state similar to suspended animation. At low - but not negative - temperature, life processes stop, but most of the tissues remain intact.

Interestingly, this happened even naturally without the participation of doctors and scientists. So, in 1999, the Swedish doctor Anna Bogenholm failedM. Gilbert, R. Busund, A. Skagseth et al. Resuscitation from accidental hypothermia of 13 7 °C with circulatory arrest / The Lancet under the ice, skiing, and spent in cold water 80 minutes. The body temperature dropped to 13.7 °C and the heart stopped. Doctors ventilated the organs, connected the girl to a heart-lung machine. As a result, Bogenholm made a full recovery, although she later experienced problems due to the fact that some of the nerves in her arms and legs had died.

A similar incident happenedD. Dovey. Suspended Animation? How A Boy Survived 15 Minutes Trapped Under Ice In Frozen Lake / Medical Daily in 2014 in the USA. 14-year-old boy from Missouri John Smith fell through the ice and was in cold water for 15 minutes. After being taken to the hospital, he remained unresponsive for another 27 minutes. cardiopulmonary resuscitation. However, the doctors were able to save the guy with the help of approximately the same measures that were once used in the situation with Bogenholm.

How can you put a person into suspended animation

Scientists consider two ways.

1. With hypothermia

You can't freeze a person, but you can cool him down. And although it sounds crazy, such a trick can be useful in treating the wounded with great blood loss.

The internal organs of such victims most often stopS. Tisherman, H. Alam, P. Rhee et al. Development of the emergency preservation and resuscitation for cardiac arrest from trauma clinical trial / Journal of Trauma and Acute Care Surgery work for lack of oxygen, and people die. For example, brain cells begin to die after five minutes of oxygen starvation. However, if the body is abruptly cooled to about 10-15 ° C, the cells can live a couple more hours - the processes in them will slow down. This will give the medics extra minutes to get the patient to the hospital.

During the procedure, the blood of the victim is pumped out, and cold (2–4 ° C) saline saline is passed through the aorta through his veins. The body temperature will begin to drop rapidly (2 ° C per minute), vital processes will slow down, and the heart will stop. In this case, the cells will consume significantly less oxygen and will not be destroyed. After the end of the operation, the patient will be gradually bled back and resuscitated.

While it sounds like fantasy, a plan like this could work.

This technology was first testedx. wu, T. Drabek, P. M. Kochanek et al. Induction of Profound Hypothermia for Emergency Preservation and Resuscitation Allows Intact Survival After Cardiac Arrest Resulting From Prolonged Lethal Hemorrhage and Trauma in Dogs / Circulation on dogs in 2005. Animals with severe bleeding were divided into several groups. One was undergoing routine cardiopulmonary resuscitation while the surgeon tried to stop blood. Others were filled with saline instead of blood, the temperature was lowered and the heart was stopped, and then an operation was performed and blood flow was restored. In total, the animals were in a “chilled” state for either 12 or 36 hours. Not a single dog survived in the CPR group, and 12 out of 14 in the suspended animation groups. Although the animals were actually dying for almost three hours, their brains were not affected.

Another similar experience wasH. Alam, P. Rhee, K. Honma et al. Does the Rate of Rewarming from Profound Hypothermic Arrest Influence the Outcome in a Swine Model of Lethal Hemorrhage? / The Journal of Trauma: Injury, Infection, and Critical Care in 2006 on pigs. They also caused heavy bleeding, and then immersed in suspended animation. Animals survived in 90% of cases with an average rate of return to normal temperature of 0.5 °C per minute. At the same time, their hearts in most cases started by themselves after the back filling of blood. Experimental pigs also showed no impairment of brain activity.

This method gotP. Asfar, E. Calzia, P. Radermacher. Is pharmacological, H2S‑induced ‘suspended animation’ feasible in the ICU? / Critical care called "Emergency Preservation and Resuscitation" (EPR). While there is a possibility that it could work in humans, the dangers associated with EPR are not yet fully understood. So, hypothermia can lead to a shift in the acid-base balance of the body, blood clotting disorders and worsening immunity.

With the help of hydrogen sulfide

Similar results can be achieved without blood transfusions and body cooling. To do this, scientists try 1. P. Asfar, E. Calzia, P. Radermacher. Is pharmacological, H2S‑induced ‘suspended animation’ feasible in the ICU? / Critical care
2. C. Hartman, b. Nussbaum, E. Calzia et al. Gaseous Mediators and Mitochondrial Function: The Future of Pharmacologically Induced Suspended Animation? / Frontiers in Physiology induce a suspended animation-like state with non-lethal doses of hydrogen sulfide and other gases. Correctly calculated concentration in theory will reduce the consumption of oxygen by the cells of the body, which is why life processes again slow down greatly.

In 2005, a group of American scientists reportedE. Blackstone, M. Morrison, M. b. Roth. H2S Induces a Suspended Animation–Like State in Mice / Science, which was able to successfully cause a decrease in body temperature in mice. The experimental animals were left in a special chamber for six hours, into which particles of hydrogen sulfide were then fed. The concentration was about 10% of deadly for a person.

Within the first five minutes of the experiment, the mice's body temperature dropped to 13°C, their heart rate slowed from 500 to 200 beats per minute, and their respiratory rate dropped from 120 to 25 breaths per minute.

The supply of ordinary air without hydrogen sulfide gradually returned the animals to normal. Later, additional experiments were carried out, which showed that immersion of rodents into suspended animation with the help of gas can also be used for severe bleeding. So, it was possible to reduce mortality from lack of oxygen in mice. More scientists have discoveredC. Hartman, b. Nussbaum, E. Calzia et al. Gaseous Mediators and Mitochondrial Function: The Future of Pharmacologically Induced Suspended Animation? / Frontiers in Physiologythat hydrogen selenide (H₂Se).

However, such experiments on larger animals, pigsJ. Li, G. Zhang, S. Cai et al. Effect of inhaled hydrogen sulfide on metabolic responses in anesthetized, paralyzed, and mechanically ventilated piglets / Pediatric Critical Care Medicine and sheepP. Hauzi, V. Notet, b. Chenuel et al. H2S induced hypometabolism in mice is missing in sedated sheep / Respiratory Physiology & Neurobiology, were not successful. Their metabolism did not slow down. The problem turned out to be different metabolic rates in large and small mammals. While mice, with their fast metabolisms, could be put into suspended animation within minutes, pigs and sheep took much longer for the gas to spread throughout the body. Based on these observations, scientists came to the conclusion that hibernation with the help of hydrogen sulfide is unlikely to be induced in humans in case of an emergency.

Perhaps the hydrogen sulfide method will workP. Asfar, E. Calzia, P. Radermacher. Is pharmacological, H2S‑induced ‘suspended animation’ feasible in the ICU? / Critical careif there is more time left. So, some decrease in temperature and oxygen consumption in pigs was still observed, but only after 10 hours of gas exposure. And there is also the suggestion that the combination of hypothermia and hydrogen sulfide can give a quick and tangible result.

Have you been able to do this with a human?

The developers of the hypothermic method - Samuel Tisherman and his team of doctors - decided to move from experiments with animals to experiments on humans. In 2014, the US Food and Drug Administration approved for the first timeH. Thomson. Gunshot victims to be suspended between life and death / New Scientist such a research program.

According to her, it was supposed to compare the survival of 10 patients resuscitated by on-call investigators using hypothermia with 10 who were rescued by conventional methods. These were supposed to be people with gunshot or stab wounds and a lot of blood loss, whose heart stopped no later than five minutes before the start of the procedure. The experiment itself became possible only because there are simply no other methods of saving such patients.

However, finding suitable patients proved difficult, and Tisherman's team managed to successfully put a person into suspended animation for the first time only five years later, in 2019. The scientist reportedH. Thomson. Exclusive: Humans placed in suspended animation for the first time / New Scientist in an interview with New Scientist magazine. However, Tisherman did not tell, survivedI. sample. Humans put into suspended animation for the first time / The Guardian patient or not. Neither the fate of the man nor the further results of the EPR study are yet known. Since 2019, Tisherman has releasedS. A. Tisherman. Emergency preservation and resuscitation for cardiac arrest from trauma / Annals of the New York Academy of Sciences there is only one article on this topic, in which he did not tell anything new.

When scientists can put people into hibernation safely and for a long time

Actually no one knowsH. Thomson. Exclusive: Humans placed in suspended animation for the first time / New Scientist. The results of the first application of hypothermic suspended animation in humans have not even been outlined yet.Emergency Preservation and Resuscitation (EPR) for Cardiac Arrest From Trauma (EPR‑CAT) / ClinicalTrials.gov in scientific publications. The EPR study itself is also not completed - the end is scheduled for 2022. However, it has already been postponed due to the pandemic.

So far, we have no data on how the human body reacts to suspended animation.

Many potential hazards, for example, are still unexplored. Thus, human cells can also be damaged when leaving the state of hypothermic anabiosis, when blood flow is restored. And the longer they are without oxygen, the worse the injury. Tisherman himself says that with the help of special preparations this effect can be smoothed out, but the reasons for its appearance are still not fully understood. Therefore, it is not known whether it is realistic to keep the body chilled for more than two hours.

However, if EPR tests are successful, and scientists find a way to reduce its negative effects and maintain this state for a long time, suspended animation will turn from fantasy into reality. But this will obviously not happen soon.