Aerocryotherapy: the effects of cold on the body

Aerocryotherapy: history and modernity

The concept of aerocryotherapy (ACT) – pulsed stimulating surface exposure to cryogenic temperatures (below –130°C) to obtain a physiological response of the body to cold – originated at the turn of the 70-80s of the twentieth century in Japan. This physiotherapeutic effect has become an addition to the main treatment of diseases of the musculoskeletal system. The Japanese experience was transferred to European soil almost simultaneously, and this new branch of medicine began to develop very quickly.

In 1982, at the Rheumatology Congress in Wiesbaden, the Japanese doctor Toshimo Yamauchi made a report on the very effective results of treating rheumatoid arthritis in a special air cryochamber with a temperature of –160°C to –180°C. From time immemorial, people have known that local cold exposure can reduce pain. T. Yamauchi and his collaborators drew attention to this phenomenon and began to actively look for ways to enhance this analgesic effect. At first glance, the way to increase the effect was obvious - it was necessary to lower the temperature of the cooling bandage. It was along this path that Japanese rheumatologists took: acting by trial and error, they exposed the joints to increasingly lower temperatures. The result of these searches turned out to be ambiguous - the joints were indeed relieved of pain, but often with severe frostbite of the skin. As subsequent studies using a mathematical model of the skin showed, due to good thermal contact between the liquid and the skin, such frostbite is inevitable. To increase the procedure time and be able to interrupt it before frostbite begins, it is necessary to worsen the thermal contact between the cooler and the skin. To do this, the Japanese replaced liquid cooling media with gas. At first, by analogy with compresses, the gas was applied locally - individual diseased joints were blown. However, it was soon noticed that the larger the area covered by the cold jet and the lower the gas temperature, the higher the positive effect. After some time, Japanese doctors moved on to total immersion of the human body in a cryogenic environment. This is how the practice of general cryotherapy arose.

T. Yamauchi's report at the Congress of Rheumatologists created a sensation among specialists, as the doctor discovered a fundamentally new approach to combating diseases of the musculoskeletal system. However, as is always the case with unexpected sensational statements, the reaction to the report was mixed. Many experts were skeptical about what they heard and reproached the author for charlatanism. But there were also many enthusiasts who wanted to reproduce the achievements of the Japanese doctor in European clinics.

At the time of the spread of the cryotherapy method in Europe, the technology and methodology for using cryotherapy were quite well developed, but the Japanese experience remained unclaimed. For a number of reasons, including economic ones (Japanese cryochamber manufacturers set an unreasonably high price for equipment), Europeans did not copy Japanese methods or buy Japanese equipment, but launched a large-scale and multifaceted search for alternative technical and medical solutions. However, despite the high activity of European manufacturers, capital and operating costs for the implementation of cryotherapy projects turned out to be too high. As a result, until the 90s of the twentieth century, cryotherapy units remained the most expensive type of therapeutic equipment.

The high cost of consumables, such as liquid air or liquid nitrogen, has stimulated the search for alternative methods of cooling the treatment area and marked the beginning of the production of installations that use multi-stage refrigeration machines. The first unit with a compression cooling system was released in Germany in 1985. The transition to an alternative cooling method provided a solution to the economic problem, reducing the cost of production, but the consequence of reducing the cost of equipment was a significant increase in the temperature of the gas in the treatment cabin. Multi-stage refrigeration machines are capable of maintaining a temperature in the treatment cabin not lower than –110ºC, which significantly reduces the therapeutic effect. If T. Yamauchi described the result of cryotherapy as relieving pain and joint stiffness for 5–6 hours, then the analgesic effect of procedures in installations with a compression cooling system lasts no more than 40 minutes.

However, along with supporters of reducing the cost of cryotherapy systems in Europe, there are still enough adherents of cryotherapy at temperatures in the range from –160ºC to –150ºC, recommended by T. Yamauchi himself. This group of doctors, in alliance with engineers, concentrated their efforts on the extensive development of aerocryotherapy - the improvement of group cryosaunas with nitrogen cooling. Due to the high cost of devices of this group, its development was possible only in the conditions of state financial support, and ACT received such support only in one country - Poland, where it became part of the state health policy.

Analyzing the history and modernity of aerocryotherapy, one cannot fail to mention the role of our neighbors, Russia, in the development of this trend. In the spring of 1986, a research project was launched in Leningrad, which 20 years later made cryotherapy an accessible and widespread procedure. During the period from 1998 to 2009, the number of cryotherapy installations in Russia increased to 200. So, in terms of the provision of cryotherapy equipment, the Russian Federation today is the undisputed world leader.

Mechanism of action of aerocryotherapy

Depending on the nature and volume of cryotherapy, ACT procedures can be local or general.

Local aerocryotherapy is a focal effect of a low-temperature gas flow, usually obtained by evaporating liquid nitrogen and directed directly to the affected area. Localization of cryotherapy is ensured by couplings or small chambers. The method is used to treat arthritis, polyarthritis, eczema, and the consequences of burn tissue damage.

General aerocryotherapy involves total or subtotal immersion of the patient’s naked body in the gas environment of a cryochamber at a temperature from –110°C to –180°C. During total immersion, the patient breathes using the air filling the cryotherapy zone; during subtotal immersion, the patient breathes outside air.

The most important advantage of cryotherapy is its physiology, unattainable by other methods. The cold persistently forces our body to independently understand its problems and find ways to eliminate them. The whole process proceeds only at the expense of a person’s own adaptogenic resources, and these resources are not only not depleted, but, on the contrary, are improved and strengthened. Cold stimulation allows the body to “remember” techniques forgotten under conditions of powerful drug support, put reserve systems into operation, forms nonspecific immunity and reduces negative reactions to allergens.

What are the outstanding abilities of cryotherapy based on? Paradoxically, on fear. Cold skin receptors are located at a depth of 0.17 mm, and when exposed to ultra-low temperatures, a signal is generated in these receptors that the body is close to frostbite. The imaginary danger of frostbite is great, but when signals are transmitted from receptors to the brain, the physical meaning of this danger is lost, and information about the place from which the signal came is lost. Thus, cryotherapy creates feelings of threat of unknown origin and unclear localization. The response to such a threat is to mobilize defense systems and search for possible causes of anxiety throughout the body. It should be remembered that by the beginning of these searches, contact with cryogenic gas has already been completed, so protective systems “revise” all levels of the body and have a corrective effect on identified deviations from the physiological norm.

Cryotherapy does not train, but stimulates the body, forcing it to independently identify and correct accumulated errors. A slight loss of heat (only 100–150 kcal is lost during the procedure) causes a powerful reaction that lasts several hours. By the nature of its effects, cryotherapy is more of a psychotherapeutic procedure. The therapeutic effect is formed through the skin sense organ, and the result depends not on the lost heat, but on the intensity of the signals in the skin receptors. It is permissible to create conditions under which powerful signals from skin receptors are possible only with a large area of contact of the skin with cryogenic gas, that is, under conditions of general aerocryotherapy.

Effect of ACT on the body

Among the most obvious positive effects that occur after undergoing the aerocryotherapy procedure is a general training (hardening) effect, manifested by an increase in the level of functioning of the main regulatory systems of the body in practically healthy people. Short-term aerocryotherapy effects lead to a slowdown in oxygen metabolism, the processes of oxidative phosphorylation of glucose in the integumentary tissues, a decrease in the consumption of oxygen and nutrients by cells, and a slowdown in the transmembrane transport of cellular metabolites. In the presence of diseases, the analgesic, anti-inflammatory, vasodilating and muscle relaxant effects of cold are manifested.

Vascular reactions

Exposure to cold in the form of ACT leads to pronounced phase changes in the activity of peripheral vessels, which is manifested by spasm of small arteries and arterioles, precapillary sphincters, and a slowdown in blood flow velocity. A therapeutically significant constriction of skin blood vessels is observed when exposed to a gas environment whose temperature ranges from –60°C to –120°C for 2 minutes. In this case, there is a rapid decrease in skin temperature on the surface to 0–10°C.

Constriction of skin vessels is the first protective phase of the vascular response to extreme cooling, aimed at preventing the penetration of the cold factor through the integument (shell) of the body to the internal tissues (core) of the body. Then the second protective phase of the vascular reaction develops in the form of a pronounced expansion of peripheral arterial vessels, which leads to active arterial hyperemia, the duration of which varies from 1 to 30 minutes, depending on the intensity of cooling. This phase is compensatory, promotes increased heat generation, prevents ischemia and tissue malnutrition. Visually, the consequences of cryotherapy are manifested by a change in the color of the skin after the procedure in the form of diffuse, bright and persistent erythema.

Systemic expansion of the integumentary vessels stimulates the functioning of the circulatory system, improves nutrition and oxygenation of all tissues of the body, and reduces the hemodynamic load on the heart muscle. Along with changes in arterial and capillary circulation, ACT provides a moderate improvement in venous outflow and, during therapeutic exposures, does not lead to stagnation of venous blood.

The reaction of the vessels of deeply located organs and tissues to an extreme cold stimulus is less pronounced than the reaction of the skin vessels. Phenomena developing in the deep tissues of the “core” of the body are not associated with the direct influence of a cold stimulus and have a secondary reflex and neurohumoral origin. However, a number of authors have shown that general ACT procedures lead to increased blood supply to internal organs, which is presumably associated with the formation of vasoactive substances.

General ACT does not cause noticeable changes in central hemodynamics, does not place increased demands on cardiac activity, does not provoke the development of myocardial ischemia, cardiac arrhythmia and conduction disturbances, and does not cause a significant increase in blood pressure during the procedure. This allows patients with concomitant cardiovascular diseases to be admitted to the procedures at the initial stages, as well as expanding the scope of application of the method for elderly and senile patients. For these patients, as well as for practically healthy people, phase changes in the state of the superficial vessels of the body provide an adequate and training load to the blood supply system. Systemic long-term dilation of skin vessels in the second phase of the vascular reaction, which occurs after the procedure, causes a decrease in total peripheral vascular resistance and, thus, reduces the load on the heart, which is a favorable factor for cardiac patients.

Nervous and muscular system

Extreme cold irritant actively affects the state of the peripheral nervous and muscular systems. The development of cold anesthesia of cutaneous receptors is a partial explanation for the analgesic effect of ACT. It has been established that the analgesic effect of ACT is realized through blocking skin pain receptors and axon reflexes, normalizing the antidromic excitability of spinal cord neurons, the participation of endogenous opioids in the implementation of the effects of ACT, as well as reducing the inflammatory response and regulating vascular tone.

Cooling of the skin, which occurs under the influence of cryogenic gas, provides muscle relaxation and eliminates muscle spasms. In addition, the effect of ACT on muscle tone helps to enhance visceral blood circulation and relieve pain in diseases of the musculoskeletal system and peripheral nervous system.

The well-known practical effect of the tonic effect of cryotherapy on people in a depressed state gives rise to speculation about the possibility of using cryogenic technology to overcome depression and stressful conditions.

Neuroendocrine system

According to a number of researchers, short-term cooling at temperatures from –130°C to –180°C leads to activation of the adreno-corticotropic system with increased production of ACTH by the anterior pituitary gland and cortisol by the adrenal cortex. This is what explains the noticeable improvements in the condition of patients with rheumatoid arthritis and some other rheumatic diseases that occur during ACT. In these patients, the severity of pain and characteristic stiffness, as well as the intensity of inflammatory manifestations, are significantly reduced. This allows you to reduce doses of antirheumatic drugs, and in the absence of pain and stiffness, actively use kinesitherapy and exercise therapy.

With extreme cooling, the production of endorphins sharply increases, which have a powerful analgesic effect, sedative and moderate euphoric effect. Such hypotheses well explain the reversible analgesic effect of general ACT, which is generalized and independent of pain.

Tissue regeneration

ACT not only relieves pain, but also accelerates regeneration processes. Observations of the results of the use of general aerocryotherapy in Medical Unit No. 122 in St. Petersburg showed that healing of fractures and treatment of burns is accelerated by 3 times.

In the presence of wounds with flaccid granulations, cryotreatment leads to a decrease in the swelling of granulations, their flattening and drying. Against this background, good healing of the skin flaps is noted. Cryotherapy can also rightfully be included in the complex treatment of patients with trophic ulcers, providing analgesic, anti-inflammatory and regenerative effects.

The immune system

General cryotherapy has a powerful effect on the immune system, providing not an immunocorrective, but an immunomodeling effect. Allergy and immunodeficiency are polar conditions of the immune system. In the first case, the immune system is too “hysterically” active and reacts to the environment inappropriately and strongly. In the second case, the immune system is too passive, it lets through and ignores objects that pose a real danger. The use of cryotherapy will bring both conditions back to normal. In this case, the procedure in both cases will be absolutely the same, but the result will be the opposite. It can be argued that cryotherapeutic effects cause an auto-correction process in the body, during which deviations from the physiological norm are identified and eliminated.

Aerocryotherapy technology

To obtain the necessary positive effects from the aerocryotherapy procedure, it is necessary to keep the patient in cryogenic gas with a temperature from –150°C to –130°C for at least 2 and no more than 3 minutes, and most of the skin should be in contact with the gas, since this In this case, the stimulating effect will be exerted on the maximum number of receptors. Therefore, it is important to dress properly (or rather, undress) before entering the cryosauna. Observations of patients and systematization of data on the effectiveness of procedures in different conditions made it possible to establish a connection between the effect of a cryotherapy procedure (for example, the duration of pain relief) and the contact area of the cryogenic gas and the skin. The positive effect of the procedure is directly proportional to the area of contact between the skin and the gas. Any clothing reduces this area and reduces the results of the procedure.

At the same time, in some cases, clothing can play a positive rather than a negative role. With any design of a cryotherapy cabin, the peculiarities of heat exchange between the gaseous environment and a vertical body and the physiological structure of the body lead to an uneven decrease in temperature on the surface of the body. Gas flows move along the body from bottom to top, so cooling of the lower extremities will occur much faster than the middle part of the body. Human physiology is designed in such a way that the reaction to external cooling is the redistribution of blood flow in favor of the central part of the body. The extremities have a temperature much lower than the integumentary layers on the body, the patient’s shins and knees cool much faster, and in some cases the procedure has to be stopped due to the negative sensations experienced by the patient in this part of the body.

Table 1. Indications and contraindications of ACT

When creating the material, articles by Baranov Yu. A., Galanova S. K., Grigorieva V. D., Kiryanova V. V., Kudokovtseva O. V., Lomakin I. I., Portnova V. V., Protsenko T. were used V., Suzdalsky D.V. and others, as well as information from the sites www.criomed.com.ua , www.cryo.by , www.cryotherapy.ru , www.krio.by , www.kriosauna.ru , www.kriosauna.zp.ua .

Full version of the article: Les Nouvelles Esthetiques Ukraine, No. 5 (69), 2011