From Big Medical Encyclopedia

SCUBA DIVING — diving and swimming under water using special equipment. Great scientific, economic, defense and cognitive value has items, promotes physical development, increases working capacity, improves a functional state and adaptation opportunities of cardiovascular and respiratory systems, develops resistance of an organism to a hypoxia and a hypercapnia, develops courage and resourcefulness at swimmers. All this caused emergence of a separate look sport (see) — the underwater sport including high-speed swimming under water, underwater orientation and underwater sports firing. On underwater sport the championships of the USSR, Europe and the world are carried out, sports categories are appropriated.

For scuba diving use flippers, a mask or glasses, a respiratory tube (set No. 1) or the underwater independent air and respiratory device on compressed air (aqualung) allowing to breathe under water (set No. 2). In a cold water (lower than 15 °) the underwater swimmer uses a diving suit which shall be easy, elastic and not pass water.

At occupations of Items cooled water, the changed conditions of audibility and visibility, breath by compressed air, differences of hydrostatic and barometric pressure, respiratory resistance, change of partial pressure of blood gases have effect on the athlete. At the same time force of action of a number of physical factors varies in big limits for rather short time terms. Besides, stay of the person under water is connected with considerable psychological tension, a cut is caused by singularity of the environment and risk elements at each immersion. The aquanautics is engaged in studying of influence of the underwater environment on the person.

During the diving breath holding causes development in the swimmer of an anoxemia (see. Hypoxia ) and hypercapnias (see). In blood a large number milk to - you collects. Besides, hard muscular work during the diving causes the increased use of oxygen and considerable oxygen «debt» by the end of diving that can lead to a bystry loss of consciousness, especially in a cold water. During diving at first increase (to 140 — 145 beats/min), and at the end of diving, on the contrary, delay of a rhythm of cordial reductions is noted. Also gradual increase in the ABP is noted. At well trained divers of the ABP changes a little, and the number of cordial reductions urezhatsya. Duration of diving is limited to reserve opportunities of an organism and more depends on its fitness. E.g., at pearl divers it makes 1,5 — 2 min., and in some cases it is even more. Due to the development of an anoxemia after diving time to breathe oxygen for elimination of oxygen «debt» and more bystry oxygenation of blood is necessary a nek-swarm, without recovery the cut is not recommended to repeat diving at once.

At high-speed swimming happen to flippers, a mask and a tube of change of cordial activity same, as at usual swimming (see), but only in less favorable conditions. It is connected with breath through a tube, edges are increased by so-called dead space and creates additional respiratory resistance. Besides, the equipment increases the volume of the swimmer and resistance to the movement. In the first seconds of the ABP raises on average to 170/110 zhm hg and constantly keeps at this level, heart rate increases to 150 beats/min; their recovery to initial level happens in 10 — 15 min. after unloading.

The most resistant and considerable fiziol, shifts in an organism of the swimmer happen during the swimming to an aqualung that is caused by pressure of a fluid column increasing in process of immersion, compression of a body, toxic and mechanical effect of gases. Besides, additional harmful space (see) and respiratory resistance during the swimming in an aqualung is more, than during the swimming with a mask and a tube that even more complicates cordial activity and breath, increasing oxygen consumption and minute volume of blood circulation. Performance of sports exercises and work under in - milk lead to significant increase in number of cordial reductions and increase in the ABP. The recovery period is slowed down, 20 min. and more proceed.

The main contraindications for occupations in Pct and especially underwater sport are heart diseases, a hypertension, disturbances of a cordial rhythm, an effect of damages and hron, pulmonary diseases, a pleura and airways, hron, diseases of kidneys and urinary tract, hron, diseases of ENT organs, a nervous system, the progressing myopia, etc.

Occupations of Pct demand strict observance of certain rules. It is necessary to complete at first a course in swimming on a water surface and under water, to learn to dive without auxiliary equipment, to study the device and service regulations of equipment and the equipment, security measure during descent under water and first-aid treatment. Persons aged from 14 years, and in a set No. 2 — from 17 years, passed special - medical the commission are allowed to sports occupations in a set No. 1. The admission to competitions is allowed in 1 — 1,5 years after the beginning of trainings. The conclusion of the medical commission at medical survey is brought as a witness the swimmer-submariner and is the basis for the admission to trainings (for a period of up to 12 months). Permission to participation in competitions is given only for 3 months after additional medical examination.

At medical control (see) special attention it is paid on a condition of ENT organs and existence of acute respiratory diseases. It is forbidden to allow to competitions of the persons having even in the absence of the complaints objective signs of overfatigue which spent sleepless night, did hard physical activity, being in a condition of strong nervous excitement or oppression and also persons even after the easiest intoxication. After meal underwater descent is allowed only in 2 hours. Self-checking of the swimmer-submariner is important addition to medical control. Its main objective — overseeing by changes of a condition of the health (working capacity, desire to train and participate in competitions) and physical development (the body weight, vital capacity of lungs, barofunction of an ear, test on breath holding, etc.). The best method of the accounting of data of self-checking is maintaining the diary (see. Self-checking of the athlete ).

Typical injuries at occupations are connected by underwater sport with impact on an organism of supertension (see. Barotrauma ), changes of partial pressure of nitrogen and oxygen. The most severe defeat — a barotrauma of lungs, edges is clinically shown by development of pheumothorax, intersticial emphysema and gas embolism. The air embolism of coronary vessels of heart and vessels of a brain is especially dangerous. For prevention of this complication it is recommended not to detain an exhalation at emersion from depth. At a barotrauma of an ear the rupture of a tympanic membrane is possible. Prevention is periodic «blowing off of ears» — an exhalation through a nose at clamped by a hand (through a mask) nostrils with the subsequent deglutitory movement. At disturbance of rise from depth sometimes develops compressed-air disease (see).

It should be noted acute air hunger (see. Hypoxia ), sometimes oxygen poisoning (see. Hyperoxia ). Development of a nitric anesthesia can be the cause of accidents under water, at Krom hold on reality, orientations is lost and there is a threat for life of the swimmer.

Long stay in a cold water can bring to to cooling of an organism (see). Prevention of this complication is rhythmical, whenever possible without stops swimming, use of protective clothes. The correct organization of occupations of Pct, systematic medical control, observance of safety regulationss, the mode of descent and rise from depths, use of a complex of the actions preventing overcooling allow to avoid possible traumatic damages.

The underwater sport taking into account factors of an aqueous medium, depth, equipment and a certain risk belongs to the category of heavy exercise stresses and in system of mass physical training of a wide spread occurance has no. As recreational and prophylactic at diseases is not applied.

Physiology of breath at scuba diving

At underwater swimmers external breath (see) is exposed to the greatest functional load. Character and expressiveness of its changes at Pct in many respects depends on a way of breath — through a tube or with use of respiratory devices (see. Oxygen and respiratory equipment ).

A special case of Pct is diving — movement under water at any breath holding. During the diving the organism is exposed to the combined action of quickly accruing hypoxias (see) and hypercapnias (see), as during the performance of hard muscular work in anaerobic conditions. Duration of diving is defined by fitness, intensity of work, depth of immersion, degree of a preliminary hyperventilation, size of partial pressure of oxygen and carbon dioxide gas in alveoluses, ability of the swimmer to a self-assessment of the developing anoxemia. The trained persons after a hyperventilation oxygen are capable to dive within 8 — 10 min.

At breath through a tube intra pulmonary pressure remains equal to atmospheric pressure, and the thorax is under hydrostatic pressure, sootvetstvuyush, its depth of immersion. Transthoracic pressure difference results, at Krom of people breathes under constant negative intra pulmonary pressure. With increase in depth negative pressure increases in lungs, and with increase in length of a tube respiratory resistance and volume of harmful space grows (see). In these conditions the breath is complicated since on its performance additional efforts are required respiratory muscles (see) for overcoming pressure of water upon a thorax and a stomach. At the same time hydrostatic pressure facilitates an exhalation. Vital capacity of lungs (see), the functional residual capacity, elastic properties of pulmonary fabric, maximal ventilation of lungs (see. Lung ventilation ) decrease, and resistance of respiratory tracts, partial pressure of carbon dioxide gas in alveoluses, load of respiratory muscles increase. E.g., at vertical water immersion on 30 cm when on bottom edge of a thorax presses in addition to atmospheric pressure a column of water in 30 cm, the vital capacity of lungs decreases by 300 — 400 ml, functional residual capacity — for 10 — 15%, elastic properties of lungs — for 20 — 30%, respiratory resistance increases for 65 — 80%. Negative pressure in lungs causes also redistribution of blood circulation and increase in intrathoracic volume of blood that reduces elastic properties of lungs, increases their diffusion capacity and respiratory resistance.

Changes of external respiration and blood circulation in lungs limit an opportunity long (more than 10 min.) swimmings with a respiratory tube.

During the swimming with use of respiratory devices and various diving equipment gas for breath is supplied in a mask and lungs under supertension. In this case breath happens in the conditions of the increased vnutrile-exact pressure. The isolated build-up of pressure in vozdukhopro-VODYASH.IKH ways causes expansion of a thorax and lungs, lowering of a diaphragm, smeshch; eniye of abdominal organs; breath urezhatsya, ventilation of the lungs increases as a result of increase of volume of breath a little, the breath is facilitated and shortened, and the exhalation is extended and at a loss, load of respiratory muscles increases. Excessive pressure in lungs reduces prisasyvayush, y effect of negative intrathoracic pressure that complicates return of blood from the periphery in the right auricle.

Except excessive pressure, additional respiratory resistance in izoliruyupdy oxygen or air devices is rendered by mechanical, aerodynamic and hydrostatic factors. The mechanical factor of resistance is connected with energy consumption of respiratory muscles on peremesh, an eniye of valves and levers, and also on deformation of springs in nodes of the respiratory device. Aerodynamic resistance arises owing to increase in density of respiratory gas mixture and volume of harmful space due to increase vozdukhoprovodyash, their ways of the respiratory device. The hydrostatic component of resistance is caused by pressure difference at the level of an arrangement of a respiratory bag (or the respiratory device) and a thorax of the underwater swimmer.

There is a certain limit obsh, its respiratory resistances (apprx. 120 mm w.g.), upon transition for borders to-rogo there is a danger of difficulty of breath, development of the expressed hypercapnia and hypoxia, losses of working capacity and approach of sharp overfatigue. Adaptations to conditions of Pct

are the cornerstone mechanisms of adaptation of an organism, a preyachda of all of system of external respiration, to performance of hard work at the accruing anoxemia and a hypercapnia.

Bibliography: Askerov A. A. and Kronstadt - Karev V. PI. Medical control at occupations underwater sport, M., 1971, bibliogr.; Underwater medicobiological researches, under the editorship of. And. 3. Kolchinskoy, page 8, 192, Kiev, 1975; Underwater sport and health, under the editorship of S. K. Andreyeva and other. M, 1980; Farfel V. S., etc. Breath and gas exchange at muscle performance in water, in book; Bio-energetics, under the editorship of A. B. Gandelsmana, page 231, L., 1973; Craig A. Century and. Ware D. E. Effect of immersion in water on vital capacity and residual volume of the lungs, J. appl. Physiol., V. 23, p. 423, 1967; H o n g S. K. a. o. Mechanics of respiration during submersion in water, ibid., v. 27, p. 535, 1969; Radovani P. Variazioni della ventilazione poimonare daterminate dair immersione in acqua. Med. d. Sport, V. 20, p. 311, 1967.

B. P. Illarionov; A. B. Korobkov, And. H. Chernyakov (physical.).