COMPRESSED-AIR DISEASE (Latin the de-prefix extraction, destruction + compressio compression, squeezing) — the morbid condition developing owing to education in blood and fabrics of live organisms of vials of gas at decrease in external pressure (at the person during the escaping of a caisson, emersion from depth on a surface, at rise on height). In literature meet and other names Must be: caisson disease, compressed-air disease of divers, high-rise compressed-air disease, or subatmospheric disease of pilots, dysbarism, aeroembolizm, desaturatsionny aeropathy, aerobullezis, «бендз». However they are less successful since they do not reflect essence of a disease or emphasize only separate forms of its manifestation. Quite often to Must be refer also other disturbances developing at decrease in external pressure such, e.g., as a meteorism, the baro-otitis, barosinusit, a barodontalgiya, high-rise fabric emphysema (see. the Atmosphere, influence of the increased and diminished pressure ; Height, main forms of decompressive frustration ), a barotrauma of lungs (see. Barotrauma ). As there is an opportunity to accurately differentiate an etiology and a pathogeny of the disturbances connected with a decompression, it is more correct to consider them, including and actually Must be as independent nozol, forms of the general group of decompressive frustration.
Experimental studying biol, actions of pressure decline was begun in 1660 by R. Boyle. In the «pneumatic machine» designed by it (a bell, from to-rogo air was extorted) he observed emergence of vials of gas in liquid of an eye of a snake. Boyle specified that emergence of gas bubbles in fluid mediums of an animal organism can be the cause of deadly functional frustration. However the problem of functional disturbances at a decompression gained practical value only in the middle of 19 century in connection with development of lacunar works and diving business. As soon as depth of works began to reach 20 — 25 m (pressure of 3 — 3,5 atm), there were mass cases of heavy functional frustration at lacunar workers (caisson disease) and the divers (compressed-air disease) arising at return to standard atmosphere pressure and shown in the form of sharp muscular and joint pains, defeats of c. the N of page, heavy is broken y cardiovascular and respiratory systems, is frequent from the death.
Goppe-Zeyler (F. Hoppe-Seyler, 1857) and Byukua (Bucquoy, 1862) showed a feedforward of a course of a disease with a decompression. Paul and Vatell (V. of Pol, T. Watelle, 1854) figuratively expressed this communication as «payment on an exit from under pressure». The B of ER (P. Bert, 1878) put forward and experimentally proved the theory of «a gas embolism» Must be. Basic researches of J. Haldane, and also A. Hill validated this theory, edges allowed not only to explain origins of a disease, but also to develop evidence-based ways of treatment and prevention.
During the studying Must be, arising during the underwater works, the hypothesis of a possibility of development of a similar disease and in high-rise conditions [A. Boycott and sotr was stated., 1908; J. Haldane, 1908, etc.; I. Henderson, 1917]. Later cases Must be really were noted in the beginning at «rises» in a pressure chamber [J. Jongbloed, 1930; V. V. Streltsov, 1932; V. G. Mirolyubov, A. P. Apollonov, 1938, P. K. Isakov and soavt., 1939, etc.], and then and in high-rise flights by airplanes [Carmichael (E. Carmichael), 1939]. There was a need for studying of features high-rise Must be, in development of prevention and means of protection of members of crews of airplanes from adverse influence of action of a tenuous atmosphere.
In 40 — the 50th 20 century were executed many researches concerning theoretical and practical questions Must be in aircraft: the clinic of a disease was studied in detail, it is proved etiol, relationship of high-rise and lacunar forms Must be, are in details investigated physical. patterns of development of gas bubbles in an organism, are revealed physical. and fiziol, the factors influencing development Must be at height, and also effective remedies of prevention and treatment of a disease are found.
Some features of conditions of space flights (hard muscular work at spacewalk, the big duration of stay in conditions of a tenuous atmosphere, a possibility of repeated decompressions during the escaping of the spaceship) increased probability of emergence Must be and demanded development of new ways of its prevention and treatment. In this direction a lot of things are made by domestic and foreign scientists: A. G. Kuznetsov, A. M. Genin, P. M. Gramenitsky, V. P. Nikolaev, D. Busby, Roth (E. Roth), Allen (T. N of Allen), Lambertsen (S. Lambertsen).
Comparative analysis of quantity of diseases Must be convincingly shows that by 70th incidence Must be, especially severe forms, considerably decreased. If in an initial stage of lacunar works (1840 — 1860) heavy Must be (caisson disease) developed almost at each case of a decompression (see. Lacunar works ), to the middle of 20 EL. it began to be observed less than at 1% of divers and 0,6% of lacunar workers.
An etiology and a pathogeny
Must be is a consequence of transition of blood gases and fabrics from the dissolved state in free — gaseous as a result of decrease in surrounding atmospheric pressure. The gas bubbles which are formed at the same time break normal blood circulation, nerve terminations irritate, deform and damage body tissues. With a standard atmospheric pressure between the partial pressure of gases in lungs and their tension in blood and body tissues there is a dynamic equilibrium. The main part of the general pressure of gases in lungs, and consequently, in blood and fabrics (apprx. 570 of 760 mm of mercury.) falls to the share of nitrogen, fiziol, the inert gas which is not participating in gas exchange. High partial pressure of nitrogen in lungs (and respectively in blood and fabrics), it fiziol, and chemical «inertness» cause its leading role in formation of gas bubbles at a decompression.
Content of nitrogen in an organism in general is defined by the level of its partial pressure, duration of exposure under existing conditions and solubility in liquids and fabrics. The solubility coefficient of nitrogen for different body tissues is various. It is highest for fatty tissue.
With a pressure of 760 mm of mercury. in 100 ml of blood contains apprx. 1 ml of nitrogen, and in 100 ml of fatty tissue in 5 times more. Contains in an organism of the adult apprx. 1 l of nitrogen, about 350 ml fall to the share of fatty tissue.
At change of partial pressure of nitrogen in an external and alveolar air time of establishment of a dynamic equilibrium (on nitrogen) for various body tissues variously. Are most quickly saturated with nitrogen and its blood, a lymph and well perfusing fabrics lose. Fatty tissue owing to bad vascularization is saturated with nitrogen much more slowly. However on long exposure at supertension because of high solubility of nitrogen in fats contents it in fatty tissue can be considerable.
At decrease in surrounding pressure (raising of the diver from depth on a surface, an exit of the worker from a caisson, raising of the pilot on height) the gas dynamic equilibrium is broken, fabrics and liquids of an organism are peresyshchenny gases, and first of all nitrogen. There is a process of desaturation (see. Saturation ). At rather slow decompression process of removal of excess nitrogen of fabrics before establishment of new gas balance usually proceeds without formation of gas bubbles. In case of rather bystry decompression the peresyshchennost of fabrics gases reaches critical levels. Conditions for vesiculation of gas in fabrics and liquids are created. Diffusion of gases from fabrics in originally arisen bubble will cause its growth before establishment of gas balance. The sizes of a gas bubble essentially depend as well on elastic elastic properties of fabric (the deforming pressure, on Fultona).
According to J. Haldane (1908), the admissible coefficient of supersaturation by nitrogen (i.e. the relation of initial pressure to final after a decompression, at Krom gas bubbles begin to be formed) for a human body makes apprx. 2,25. It means that at a 2,25-fold decompression (after emersion from depth of 12,5 m on a surface and transition from pressure 2:25 and to normal or from normal to lowered — less than 300 mm of mercury.) at the person gas bubbles can be formed and develop Must be. Divers at a decompression from very big pressure causing a high saturation of fabrics nitrogen, can have an admissible coefficient lower than 2,25. Therefore in such cases big care at a decompression is required.
Process of formation of gas bubbles in peresyshchenny gases fabrics and liquids is significantly facilitated by existence in an organism of so-called gas «germs». Them in an organism gaseous micro inclusions of 10 in size, rather stable with a standard atmosphere pressure, can carry out a role - 7 — 10 - 6 cm, cone-shaped and wedge-shaped niches on the surface of hydrophobic fabrics, «funnels» of turbulent zones of a blood-groove and especially microsites with the negative hydrostatic pressure arising at reduction of muscles. All these gas «germs» in the conditions of supersaturation of an organism nitrogen act as primary centers of formation of gas bubbles. The gas bubbles which arose in an organism at a decompression interact with fabrics, fluid mediums and undergo a certain evolution.
Distinguish two main types of post-decompressive gas bubbles. The first type — autochthonic (extravasated) bubbles, education and which involution entirely is defined by process of diffusion — exchange of gases between a bubble and the environment surrounding it. Interstitial bubbles, apparently, belong to this type. At excess of the gases dissolved in fabric they grow and put pressure upon surrounding fabrics, causing their deformation that can lead to emergence of pain. Such is, apparently, mechanism of development of muscular and joint decompressive pains. Believe that autochthonic bubbles form also in cells (in parenchymatous bodies and in fatty tissue), causing their destruction. Getting with a lymph or through the damaged vessels to a blood stream, vials of gas and products of destruction of cells can form gas and fatty emboluses.
The second type — gas bubbles which evolution is caused not only by processes of diffusion, but also merge with each other or, on the contrary, crushing on smaller. Gas bubbles shall be carried to this type in the majority intravascular. Arising in a venous bed (in fabric capillaries), they merge with each other, causing a possibility of development of an acute aeroembolism in circulatory system (fig. 1 and 2). Gas bubbles are enveloped by colloids of blood, proteins, lipoida, fats and other substances weighed in blood are postponed for their surfaces owing to what their rassasyvaniye is at a loss.
The frustration coming at an aeroembolism hemodynamics (see) it is aggravated with increase of viscosity of blood (see. Viscosity ). Sedimentation of uniform elements of blood on a surface of bubbles, the increased viscosity of blood, and also disturbance of normal relationship between a vascular wall and blood lead to formation of aero blood clots which basis is gas, and the capsule — trombotichesky weight. A wedge, effects of the aerothrombosis causing permanent disturbances of blood circulation, more serious and long than at an aeroembolism.
Disturbance of blood circulation by gas and fatty emboluses or extravasated gas bubbles causes development of defense reflex reactions in the form of expansion of arterioles and capillaries, build-up of pressure of blood and strengthening of a blood-groove. These reactions promote advance of an embolus in larger venous vessels. There is collateral circulation more intensively (see. Collaterals vascular ), directed to elimination of local ischemia (see). The aero emboluses which got with a blood flow to a right ventricle of heart are exposed to crushing on small gas bubbles. The last owing to increase of capillary pressure in process of reduction of their diameter and pressure of gases in bubbles resolve easier. It was noticed that in repeated experiences with a decompression efficiency of defense reactions increases: animals transferred a decompression easier. It allowed to assume a possibility of the directed training of an organism to rather bystry pressure decline.
For experimental reproduction Must be usually use recompression cameras and pressures chamber (see. Pressure chamber ), the gaseous fluids of a certain structure and pressure allowing to create in relation to lacunar (see. Lacunar works), diving (see. Diving works ) and aerospace practice (see. Flights, high-rise ). The aeroembolism can be modelled administration of inert gases in venous system of animals.
the Most expressed and specific morfol, changes at bystry death from heavy Must be existence of numerous gas bubbles in venous system, the right half of heart, the phenomenon of hypostasis and emphysema of lungs, the multiple centers of hemorrhages overflowed and stretched by vials of gas in various bodies and fabrics are. Sometimes in a pulmonary artery foamy blood is found. Corpses of the dead from Must be are exposed to a bystry and sharp okocheneniye. Integuments and mucous membranes of a tsianotichna.
A clinical picture
the Current, symptomatology and disease severity are defined by the size, quantity and localization of gas bubbles in an organism, existence of provocative factors and timeliness of treatment. On weight of a current conditionally distinguish three forms Must be: easy, average and heavy. The skin itch and rash, unsharp muscle, bones, joints pains and on the course of nervous trunks are characteristic of an easy form. At Must be moderately severe there is a sharp deterioration in the general state, there is a cold sweat, the severe pains in muscles, bones and joints which are followed sometimes by swelling, nausea, vomiting and also short-term loss of sight are noted. At a severe form at patients symptoms of defeat of c develop. N of page (paresis and paralyzes of extremities), cardiovascular and respiratory systems. Retrosternal pains, suffocation, cyanosis are noted, collapse (see).
Some authors allocate also deadly and hron, forms Must be (M. I. Jacobson, 1950; Myles, 1971). At a deadly form the massive aeroembolism leading to blocking of blood circulation and damages of lungs, hearts, a brain, incompatible with life takes place. Late effects of an aeroembolism and an aerothrombosis in the form of an aseptic necrosis of bones (fig. 4), the deforming osteoarthrosis, etc. are characteristic of a chronic form.
At return from supertension to normal symptoms of a disease in most cases develop within the first hour after a decompression. Sometimes they are noted already in the course of a step decompression and as an exception, in 6 — 12 hours after a decompression. It is important to remember, as rather easy symptoms at the beginning of a disease can quickly outgrow in heavy with sharp deterioration in cordial activity, fluid lungs (see) and paralysis of a respiratory center.
Must be the most frequent symptoms slowly developing dull aches more often in any one joint or about it, arising quite often at the movement are. Pains are preceded by feeling of numbness or «awkwardness» in a joint. Skin over the place of defeat can get a pale shade, sometimes becomes tumescent. At the patient the general weakness, a fever or feeling of heat is quite often noted. At sharp pains tachycardia and increase in blood pressure is observed. On the nature of pain can be aching, tearing, drilling, gnawing, shooting. They develop owing to irritation gas bubbles of interoceptors or a fabric hypoxia at obstruction of blood vessels gas bubbles, and also at irritation of nerve fibrils the bubbles which are formed in a myelin cover.
Quite often Must be it is shown by a skin itch, burning on limited or extensive areas of a body where polymorphic focal reddenings appear. Skin defeats are caused by education in vessels of skin and sweat glands of vials of gas which break blood circulation and nerve terminations irritate.
After deep-water descents at the diseased Must be approximately in 5% of cases various symptoms of defeat of c are noted. N of page: dizziness, temporary deafness, visual disturbance, aphasia, anesthesia, paresis, spastic paralyzes of one or both legs, spasms. These symptoms develop owing to formation of gas bubbles in myelin covers of fibers of motor nerves or white matter back and a brain. More often gas bubbles are formed in lumbosacral segments of a spinal cord.
At a multiple aeroembolism in cavities of the right heart and vessels of lungs the gas bubbles of various sizes causing disturbance of cardiovascular activity can accumulate in a significant amount — there are a pallor, sharp weakness, frequent and shallow breathing, the ABP falls. Retrosternal pains are noted, especially at a breath, fits of coughing. Pulse in the beginning frequent, then is slowed down, integuments become a pale gray shade or cyanotic. At the expressed phenomena hypoxias (see) and hypotensions of the patient faints.
Damage of an inner ear is a consequence of accumulation of gas bubbles in liquids and fabrics of preddverno-cochlear body; morbid condition as a menyerovsky syndrome (dizziness, nausea, vomiting, a nystagmus, weakness) develops. Complaints to fatigue, exhaustion can be antecedent signs. This syndrome usually develops after stay of divers at big depths with performance heavy physical there. works, and also at disturbances of a decompression.
the Diagnosis is made on the basis of characteristic complaints and a wedge, symptoms which appear after a decompression. At the same time it is necessary to consider strictly both the mode of a decompression, and a condition of stay under supertension. Emergence of a skin itch, pain, a menyerovsky syndrome, paralyzes, sudden development of a collapse — all this at the accounting of the previous decompression serves as the direct proof Must be. Correctness of the diagnosis is checked by the repeated room of the supertension which was injured in conditions (recompression). If symptoms of a disease are stopped — the diagnosis is right; if during the carrying out recompression symptoms do not disappear and do not even weaken, then the diagnosis Must be becomes very doubtful.
At rentgenol, inspection in some cases Must be find gas bubbles in cavities of joints (fig. 3), bubbles in synovial vaginas of sinews, fastion of muscles, okolososudisty educations. However diagnostic value of such finds is relative: they can be found without wedge, displays of a disease and to be absent at the expressed its symptoms.
Sometimes at a X-ray analysis the characteristic aseptic necroses of bones (fig. 4) deforming osteoarthroses come to light — effects Must be postponed. Necroses represent the centers of destruction, fascinating 1/3 — 1/2 epiphysis of a bone, but are sometimes noted also in a diaphysis. Usually necroses develop in femurs — in their proximal epimetafizarny departments. On the joint surface of the affected bone defects of fabric are formed. In a head, a neck and spits of a hip the structure of a bone tissue, and also joint cartilage is broken that leads to development of the deforming osteoarthrosis (see. Arthroses ). Damages of bones more often bilateral, symmetric also develop within several years after transferring Must be. Sometimes deformation and flattening of bodies of chest vertebrae (a lacunar platyspondylia) are found.
In experimental practice attempts of use of ultrasound for a location of gas bubbles in an organism of animals and the person become at a decompression.
Must be the Radical way of treatment recompression — impact on the patient with supertension in the recompression camera is. The method is based that at build-up of pressure the gas bubbles which are in an organism of the patient decrease in volume and are dissolved. Recompression promotes a rassasyvaniye of bubbles, i.e. elimination etiol, a factor of a disease. The subsequent decompression to standard atmosphere pressure is made slowly taking into account laws of desaturation of an organism from excess of inert gas without formation of gas bubbles. Medical recompression is carried out on the special modes. Depending on a condition of the patient apply also a symptomatic treatment: the stimulation of cardiovascular system, warming, oxygen, sedatives, actions directed to prevention or elimination of a fluid lungs. New methods of treatment are developed Must be, in particular hyperbaric oxygenation (see. Hyperbaric oxygenation , Hyperoxia ).
the Forecast depends on a look and weight of frustration, and also on timeliness and correctness of treatment. Effective and bystry, within the first hours, treatment Must be guarantees an absolute recovery even at the most severe forms of a disease.
Prevention is provided first of all with strict observance of the modes of a decompression and recompression. Carrying out preliminary medical selection of divers and lacunar workers (see. Professional selection), implementation of requirements for a duty under supertension, an exception of provocative factors (heavy physical. loading, cooling, hypercapnia, etc.) reduces possibility there is
a High-rise compressed-air disease
the High-rise compressed-air disease develops at a decompression from standard atmosphere pressure to lowered — in high-rise flights, at «rises» in a pressure chamber, spacewalk, rises without preliminary desaturation; usually arises the first 15 — 60 min. stay with a pressure less than 300 mm of mercury. (height more than 7000 m). At smaller heights Must be can develop in 2 — 4 hours after a decompression. The most frequent symptoms — muscular and joint pains therefore the disease is quite often called by «high-rise pains». However severe forms (suffocation, paralyzes, a collapse) and even death are possible. Without use of preventive measures the frequency and disease severity are in direct dependence on the level of height (frequency rate and the size of a decompression), time of stay at height, the speed of a decompression and action of provocative factors (muscular work, cold, a hypercapnia, obesity). The disease is stopped by descent to height less than 7000 m or build-up of pressure in a cabin and high-rise equipment (see) to perhaps bigger level. In hard cases apply to lay down. recompression to 3 — 5 at.
Prevention of a high-rise compressed-air disease is provided with use of hermetic cabins (see. Cabins of aircraft ), space suits, preliminary desaturation of an organism from nitrogen by means of breath by oxygen (see. Oxygen therapy ). See also Hypobaropathy .
The compressed-air disease in the medicolegal relation
the Compressed-air disease in the medicolegal relation matters at a research of corpses of the persons who died at bystry rise from depth on a surface (lacunar works) in high-rise conditions, and also in cases of survey of living persons, injured during lacunar and other works in case of accidents, accidents and violation of the rules of the accident prevention in the conditions of supertension. Court. - medical examination is begun with studying of the materials presented to the order of the expert by investigating authorities. Data on depth matter, on a cut underwater works, a rise time on a surface, height were conducted, on a cut there was an accident, technical condition of the equipment, speed of approach of death, etc.
From a wedge, data pay attention to characteristic symptoms Must be: a mialgiya and an osteoarthralgia, a skin itch, paralyzes, paresis, headaches with localization in frontal area, ear pain. Vestibular frustration (a menyerovsky syndrome) also are typical, an asthma, pains on the course went. - kish. path («high-rise» meteorism).
At external examination of a corpse the following signs have diagnostic value: intensive cyanotic-violet livors mortis, hypodermic hemorrhages in a face («an ekhimotichesky mask»), a back, a breast and other parts of a body, hemorrhage in conjunctivas. There can be traces of an involuntary urination and defecation. In case of hypodermic emphysema crepitation, especially on open parts of a body is defined (it is more often happens at barotraumas of lungs).
At an internal research of a corpse expert significance is attached to such signs as a sharp plethora of internals and fabrics, punctulate hemorrhages under serous covers (under a visceral pleura and an epicardium), in mucous membranes of airways and okolonosovy bosoms, injuries of a tympanic membrane, hemorrhage in an inner ear etc. In veins (is much more rare in arteries) internals — preferential lungs, a liver, heart and a brain, in veins of a mesentery, intestines a large number of vials of nitrogen is noted. At deaths door from Must be, as a rule, the air (gas) embolism of heart is defined. Conducting test on an air embolism is obligatory. Vials of gas meet also in hypodermic cellulose, parenchymatous bodies, synovial fluid of joints. Existence of vials of gas in the bodies depositing blood — a liver, a spleen, and also in a lymph is characteristic.
Find clots which emerge during the placing in water because of the small vials of gas which are contained in them in cavities of the right half of heart and veins. These clots it is long are not exposed to putrefactive changes and therefore give the chance to establish death from a gas embolism even in cases of rotting of a corpse.
Gistol, a research reveals the changes corresponding to those which are observed at acute air hunger (see. Hypoxia ).
It is known that vials of nitrogen, collecting in fatty tissue, destroy its cells which contents on limf, to ways get to blood vessels. Thereof there is a fatty vascular embolism of lungs, a brain and other bodies with ischemia of the respective sites. Fatty embolism (see) testifies about bystry and high (on degree) decompressions.
At electronic microscopic examination of pieces of a liver in its capillaries the erythrocyte agglutinates arising around gas bubbles are found. In hepatocytes the cytoplasmic reticulum sharply extends and contours of kernels are deformed. These morfol, signs are very steady, remain even in a day after approach of death and are characteristic of high-rise emphysema. These signs have special value at a research of the dismembered corpse.
For diagnosis of a gas embolism also the radiographic research can be used. Results of technical expertize are of great importance. In all cases at court. - a medical research of a corpse carrying out blood samples and internals on alcohol and carbon monoxide is obligatory.
Bibliography: Avdeev M. I. Course of forensic medicine, M., 1959; Genin A. M. and d river. Research of the effective modes of desaturation of a human body for prevention of high-rise decompressive frustration, Tousle. biol, and medical, No. 3, page 34, 1973; Gramenitsky P. M. Decompressive frustration, M., 1974; Isakov P. K. and d river. Theory and practice of an air medicine, M., 1975, bibliogr.; Myles S. Underwater medicine, the lane with English, page 161, M., 1971; Nikolaev V. P. Formation of gas bubbles in the satiated solutions and in a live organism at a decompression, Tousle. biol, and medical, No. 5, page 55, 1969; Fundamentals of bioastronautics and medicine, under the editorship of O. G. Gazenko and M. Calvin, t. 2 — 3, M., 1975; Underwater sport in kliniko-physiological lighting, under the editorship of. A. E. Mazina, etc., page 141, M., 1969; Bioastronautics data book, ed. by J. F. Parker a. R. Vita, p. 25, Washington, 1973; Buckles R. G. The physics of bubble formation and growth, Aerospace Med., v. 39, p. 1062, 1968, bibliogr.; Busby D. E. Space clinical medicine, p. 37, Dordrecht, 1968.
And. H. Chernyakov; P. P. Shirineky (court. - medical).