Scuba Diving: Reactivity of Breathing of Sound, Color, and Object Sizes but Also to Deal with Surrounding Water

Home , Diving bell, Diving cylinder, The Last Dive

ssary to adjust to pressure and a different perception air in the bag had always the same pressure as the Scuba diving: reactivity of breathing of sound, color, and object sizes but also to deal with surrounding water. Modern breathing devices ope- cold, dehydration and many other dangers. rate on this principle, even though they are of cour- Scuba diving is quite diverse. For example, it can be se much more technologically advanced (Oyhenart, gases divided into freediving and scuba diving. This may 2004). be done in freshwater tanks or in the sea; it can con- The diving bell, or caisson, is a chamber that is open Michal Mašek1, Staša Bartůňková1, Michal Štefl1, Jiří Suchý2 sist of wreck or cave diving, diving with air or with at the bottom and filled with compressed air, ena- 1 Faculty of Physical Education and Sport, Charles University in Prague, Department of Physiology and a combination of various breathing gases, etc. This bling man to stay or work underwater. It is the oldest Biochemistry, Czech Republic sport always involves some degree of risk, mainly known device for prolonged work under water. Aris- 2 Faculty of Physical Education and Sport, Charles University in Prague, Department of Pedagogy, Psycho- related to the changing behavior of gases underwa- totle already described this device in the 4th centu- logy and Didactics of Physical Education and Sport, Czech Republic ter, possibly causing health complications associated ry BC. In 1535, Guglielmo de Lorena used a device with compression and decompression. similar to modern diving bells. The diving bell was Abstract Diving has become a widespread sport. The number also used to salvage the cannons from the Swedish This review article addresses the topic of scuba diving in terms of both history and the current state of unde- of professional and recreational divers is estimated to warship Vasa shortly after it sank in 1628. In 1690, rstanding on the reactivity of breathing gases in hyperbaric environment. The article is divided into two be 7 million with an annual increase in new divers Edmund Halley designed a modernly constructed parts. The first part summarizes the findings on the history of diving, the first experiments with caissons, approaching 500,000. Published statistics reveal alar- caisson, equipped with windows for seabed research, and subsequent problems and their solutions. The second part of this research deals with the physiology of ming numbers (Vann, 2005). In the U.S. alone, 100 to which air was supplied in ballasted barrels (Oyhe- respiration, the behavior of breathing gases and their interrelations in high hydrostatic pressure environment. cases of drowning and 1100 cases of decompression nart, 2004). The aim of this work is to provide comprehensive information about the history of diving and important sickness have been reported in one year. It is there- Even experimental underwater habitats are con- knowledge about the physiology of underwater breathing, as scuba diving is one of the many specific outdoor fore crucial that everyone interested in this beautiful structed on the diving bell principle. The caisson, a activities where knowledge of physiology, anatomy, and the overall functioning of the human organism is sport is appropriately instructed. special diving bell, is used during the construction of needed for its pursuit. underwater structures. The term originates from the Methodology French word caisson. The air pressure in the caisson Key words: This review article is based on the study of academic is the same as in water, which allows staying inside it scuba diving, respiratory physiology, decompression sickness, nitrogen intoxication, hypercapnia, hypo- literature, scientific articles, publications and accessi- without a special suit (Bennett, 1982). A compressor capnia, hypoxia, hyperoxia, asphyxia ble specialized web databases. The aim of the work is is attached to the caisson, supplying air and changing to familiarize the reader with the latest findings on vitiated air. If the compressor supplies higher air pre- Souhrn the behavior of breathing gases in hyperbaric envi- ssure, the excess air escapes around the edges of the Přehledový článek se zabývá problematikou přístrojového potápění jak z hlediska historie, tak i stavu součas- ronment. In the search for information, the following bell to the water surface. ných poznatků o reaktivitě dýchacích plynů v hyperbarickém prostředí. Článek je rozdělen na dvě části. První keywords were used: diving, respiratory physiology, Caissons are also frequently used for work on the část rekapituluje poznatky z historie potápění, první pokusy s kesony, následné problémy a jejich řešení. Druhá carbon dioxide, hypercapnia, hypoxia, asphyxia. The foundation of bridge piers. Caissons are mostly made část této rešerše se zabývá fyziologií dýchání, chováním dýchacích plynů a jejich vzájemnými vztahy v prostředí selective criteria of primary documents for this stu- of steel or concrete. They sink under their own wei- s vysokým hydrostatickým tlakem. Cílem práce je podat ucelené informace o historii potápění a důležitých po- dy consisted in their full-length publication in major ght into a work pit and workers inside can then dig znatcích z oblasti fyziologie dýchání pod hladinou, neboť potápění s přístrojem je jednou z mnoha specifických scientific journals and academic monographs, pub- the bedrock. Subsequently, the caisson can be filled outdoorových aktivit, při jejímž provozování je nutné mít znalosti v oblasti fyziologie, anatomie i celkového lished since 2000. An exception was made in the case with concrete and be used as a part of the pier. Cai- fungování lidského organismu. of historical sources. The review study was designed ssons have been used for work under water since the in accordance with the instructions for this type of nineteenth century. As in other diving activities, it Klíčová slova: publications (Hendl, 2007). is necessary to follow correct decompression proce- přístrojové potápění, fyziologie dýchání, dekompresní nemoc, dusíkové opojení, hyperkapnie, hypokapnie, dures when working inside of caissons. If pressure is hypoxie, hyperoxie, asfyxie. Diving history not gradually decreased, caisson disease may arise. The earliest preserved records of fully functional Following the widespread use of caissons, divers ex- Introduction phere, of the impact of individual gases on the orga- diving equipment are about six millennia old (Vr- perienced an increased occurrence of decompressi- At the turn of the nineteenth century, industriali- nism depending on their partial pressures, and also bovský, 1998). Other, though not entirely reliable, on sickness. In sport diving, caissons are currently zation led to a significant development of various of the changes in gases at an increasing hydrostatic references to diving come from the days of the Assy- mostly used to diversify diving (Bookspan, 2005). sectors, including sports. This was also the case of pressure. This information led to the creation of rian Empire. In sources from Ancient Greece, we can The first documented case of caisson disease (de- diving, thanks to the development of new materials decompression tables that determined the speed at already find more reliable information in the work compression sickness - DCS), was already described and the subsequent improvement of diving equip- which a diver should emerge to the surface in rela- of Herodotus and Aristotle, who even described the in 1841. The symptoms were described by a mining ment and diving suits. tion to the depth of immersion and the time spent use of a diving bell (Oyhenart, 2004). The oldest engineer, who observed pain and convulsions in mi- New medical knowledge has had a significant im- underwater (Oyhenart, 2004). and most primitive devices were air tanks - flexible ners who were exposed to higher air pressure in a pact on diving, especially in the field of diffusion Even today, a person who wants to engage in diving leather bags, from which divers could breathe under- shaft, from which water was drawn. Another repor- and transport of breathing gases, of chemical cont- activities has to have appropriate knowledge and water. With increasing depth, the bag decreased in ted case of decompression sickness describes the ex- rol of respiration, etc. This was also related to new skills, as diving still counts among the outdoor acti- volume proportionally to the surrounding pressure perimental submarine dive of the Sub Marine Explo- knowledge of the composition of the Earth’s atmos- vities entailing many risks. At great depths, it is nece- of the water environment, so that the compressed rer in 1867, during which the diving pioneer Julius

40 journal of outdoor activities Volume 7 No. 1/2013 ISSN 1802-3908 41 ssary to adjust to pressure and a different perception air in the bag had always the same pressure as the Scuba diving: reactivity of breathing of sound, color, and object sizes but also to deal with surrounding water. Modern breathing devices ope- cold, dehydration and many other dangers. rate on this principle, even though they are of cour- Scuba diving is quite diverse. For example, it can be se much more technologically advanced (Oyhenart, gases divided into freediving and scuba diving. This may 2004). be done in freshwater tanks or in the sea; it can con- The diving bell, or caisson, is a chamber that is open Michal Mašek1, Staša Bartůňková1, Michal Štefl1, Jiří Suchý2 sist of wreck or cave diving, diving with air or with at the bottom and filled with compressed air, ena- 1 Faculty of Physical Education and Sport, Charles University in Prague, Department of Physiology and a combination of various breathing gases, etc. This bling man to stay or work underwater. It is the oldest Biochemistry, Czech Republic sport always involves some degree of risk, mainly known device for prolonged work under water. Aris- 2 Faculty of Physical Education and Sport, Charles University in Prague, Department of Pedagogy, Psycho- related to the changing behavior of gases underwa- totle already described this device in the 4th centu- logy and Didactics of Physical Education and Sport, Czech Republic ter, possibly causing health complications associated ry BC. In 1535, Guglielmo de Lorena used a device with compression and decompression. similar to modern diving bells. The diving bell was Abstract Diving has become a widespread sport. The number also used to salvage the cannons from the Swedish This review article addresses the topic of scuba diving in terms of both history and the current state of unde- of professional and recreational divers is estimated to warship Vasa shortly after it sank in 1628. In 1690, rstanding on the reactivity of breathing gases in hyperbaric environment. The article is divided into two be 7 million with an annual increase in new divers Edmund Halley designed a modernly constructed parts. The first part summarizes the findings on the history of diving, the first experiments with caissons, approaching 500,000. Published statistics reveal alar- caisson, equipped with windows for seabed research, and subsequent problems and their solutions. The second part of this research deals with the physiology of ming numbers (Vann, 2005). In the U.S. alone, 100 to which air was supplied in ballasted barrels (Oyhe- respiration, the behavior of breathing gases and their interrelations in high hydrostatic pressure environment. cases of drowning and 1100 cases of decompression nart, 2004). The aim of this work is to provide comprehensive information about the history of diving and important sickness have been reported in one year. It is there- Even experimental underwater habitats are con- knowledge about the physiology of underwater breathing, as scuba diving is one of the many specific outdoor fore crucial that everyone interested in this beautiful structed on the diving bell principle. The caisson, a activities where knowledge of physiology, anatomy, and the overall functioning of the human organism is sport is appropriately instructed. special diving bell, is used during the construction of needed for its pursuit. underwater structures. The term originates from the Methodology French word caisson. The air pressure in the caisson Key words: This review article is based on the study of academic is the same as in water, which allows staying inside it scuba diving, respiratory physiology, decompression sickness, nitrogen intoxication, hypercapnia, hypo- literature, scientific articles, publications and accessi- without a special suit (Bennett, 1982). A compressor capnia, hypoxia, hyperoxia, asphyxia ble specialized web databases. The aim of the work is is attached to the caisson, supplying air and changing to familiarize the reader with the latest findings on vitiated air. If the compressor supplies higher air pre- Souhrn the behavior of breathing gases in hyperbaric envi- ssure, the excess air escapes around the edges of the Přehledový článek se zabývá problematikou přístrojového potápění jak z hlediska historie, tak i stavu součas- ronment. In the search for information, the following bell to the water surface. ných poznatků o reaktivitě dýchacích plynů v hyperbarickém prostředí. Článek je rozdělen na dvě části. První keywords were used: diving, respiratory physiology, Caissons are also frequently used for work on the část rekapituluje poznatky z historie potápění, první pokusy s kesony, následné problémy a jejich řešení. Druhá carbon dioxide, hypercapnia, hypoxia, asphyxia. The foundation of bridge piers. Caissons are mostly made část této rešerše se zabývá fyziologií dýchání, chováním dýchacích plynů a jejich vzájemnými vztahy v prostředí selective criteria of primary documents for this stu- of steel or concrete. They sink under their own wei- s vysokým hydrostatickým tlakem. Cílem práce je podat ucelené informace o historii potápění a důležitých po- dy consisted in their full-length publication in major ght into a work pit and workers inside can then dig znatcích z oblasti fyziologie dýchání pod hladinou, neboť potápění s přístrojem je jednou z mnoha specifických scientific journals and academic monographs, pub- the bedrock. Subsequently, the caisson can be filled outdoorových aktivit, při jejímž provozování je nutné mít znalosti v oblasti fyziologie, anatomie i celkového lished since 2000. An exception was made in the case with concrete and be used as a part of the pier. Cai- fungování lidského organismu. of historical sources. The review study was designed ssons have been used for work under water since the in accordance with the instructions for this type of nineteenth century. As in other diving activities, it Klíčová slova: publications (Hendl, 2007). is necessary to follow correct decompression proce- přístrojové potápění, fyziologie dýchání, dekompresní nemoc, dusíkové opojení, hyperkapnie, hypokapnie, dures when working inside of caissons. If pressure is hypoxie, hyperoxie, asfyxie. Diving history not gradually decreased, caisson disease may arise. The earliest preserved records of fully functional Following the widespread use of caissons, divers ex- Introduction phere, of the impact of individual gases on the orga- diving equipment are about six millennia old (Vr- perienced an increased occurrence of decompressi- At the turn of the nineteenth century, industriali- nism depending on their partial pressures, and also bovský, 1998). Other, though not entirely reliable, on sickness. In sport diving, caissons are currently zation led to a significant development of various of the changes in gases at an increasing hydrostatic references to diving come from the days of the Assy- mostly used to diversify diving (Bookspan, 2005). sectors, including sports. This was also the case of pressure. This information led to the creation of rian Empire. In sources from Ancient Greece, we can The first documented case of caisson disease (de- diving, thanks to the development of new materials decompression tables that determined the speed at already find more reliable information in the work compression sickness - DCS), was already described and the subsequent improvement of diving equip- which a diver should emerge to the surface in rela- of Herodotus and Aristotle, who even described the in 1841. The symptoms were described by a mining ment and diving suits. tion to the depth of immersion and the time spent use of a diving bell (Oyhenart, 2004). The oldest engineer, who observed pain and convulsions in mi- New medical knowledge has had a significant im- underwater (Oyhenart, 2004). and most primitive devices were air tanks - flexible ners who were exposed to higher air pressure in a pact on diving, especially in the field of diffusion Even today, a person who wants to engage in diving leather bags, from which divers could breathe under- shaft, from which water was drawn. Another repor- and transport of breathing gases, of chemical cont- activities has to have appropriate knowledge and water. With increasing depth, the bag decreased in ted case of decompression sickness describes the ex- rol of respiration, etc. This was also related to new skills, as diving still counts among the outdoor acti- volume proportionally to the surrounding pressure perimental submarine dive of the Sub Marine Explo- knowledge of the composition of the Earth’s atmos- vities entailing many risks. At great depths, it is nece- of the water environment, so that the compressed rer in 1867, during which the diving pioneer Julius

40 journal of outdoor activities Volume 7 No. 1/2013 ISSN 1802-3908 41 H. Kroehl died. Another situation reported in 1869 attributed to the COMEX Hydra 11 team. In 1992, Control respiration Specifics of gas behaviour in hyperbaric also resulted from diving activities, in which the di- the team achieved a depth of 701 meters at a pressure Breathing is controlled by neural and chemical enviroment ver used an air-filled helmet (Vrbovský et al., 1997). of 7181 kPa (Levett, 2008). mechanisms. Peripheral nervous control occurs During diving, hydrostatic pressure and temperature If the pressure decreased too fast, nitrogen was relea- in the lungs and is related with the stimulation of of the surrounding water changes, and it is thus ne- sed too quickly and bubbles formed within tissues of Physiology of respiration receptors during the inspiratory expansion of the cessary to accept gas behavior, subject to the laws of the body. They caused symptoms of divers’ disease, The composition of inhaled air corresponds to alveoli. This feedback stimulation inhibits the tone physics. ranging from itching, rashes, and joint pain to failure approximately 78 % of nitrogen (N), 21 % of oxygen of the inspiratory center and expiratory occurs, al- of sensory input, paralysis, and death. (O2), 1 % of rare gases and 0.03 % of carbon dioxide ternating rhythmically with inhalation. The respi- Nitrogen

French philosopher Paul Bert conducted extensive (CO2), while exhaled air has a varying composition ratory center is located in the medulla oblongata, Nitrogen, as an inert gas, does not cause any pro- research in the area of decompression sickness. In at different stages of the exhalation process. When with an inhalation (inspiration) and exhalation blems at normal atmospheric pressure (1 atm). Du- 1878, he discovered that the breathing of compre- exhalation begins, its percentage composition is the (expiration) region. To a certain extent, the cen- ring a diver´s descent, it dissolves well like other ga- ssed air leads to the accumulation of large amounts same as in inhaled air, since air is exhaled from a ter’s control is volitional, subject to the cerebral ses. Divers describe a certain “descent comfort.” Yet of nitrogen in the body, which dissolves in the blo- dead space of approximately 150 - 230 ml. In the se- cortex. We can choose how we breathe or when already at a pressure of 3 – 4 atm, at a depth of about odstream and bodily tissues. At a sudden pressure cond stage of exhalation, alveolar air, containing less we stop breathing for some time. Nevertheless, 30 meters, nitrogen can have narcotic effects, and drop, nitrogen cannot be naturally released from O2 and more CO2, is expelled. The total volume of air the control is mostly involuntary. The impulse for nitrogen narcosis can occur. A predisposition, such the bloodstream. This results in the formation of gas during inhalation and exhalation is about 500 – 600 the chemical control of respiration is the change as stress, fatigue, cold, hard work, CO2 accumulati- bubbles in the entire body. The resulting pain expe- ml. The air we breathe is cleansed, moisturized, and of partial pressures of breathing gases, oxygen on, or even alcohol, can lead to this condition. The rienced by divers and construction workers was first warmed by passing through the respiratory tract. On partial pressure (pO2) and carbon dioxide partial danger lies in the frequent unawareness of the symp- attributed to rheumatism. To overcome this issue, the contrary, the air we exhale is cooled down. pressure pCO2), as well as the degree of acidity or toms, such as euphoria and impaired concentration Bert recommended them to ascend to the surface at The gas exchange between blood and inhaled air oc- alkalinity of blood (pH), acting as feedback. The or decision-making. The narcotic effects of nitrogen a slower pace. This measure immediately resulted in curs in the small pulmonary circulation system. The gas exchange occurs by simple diffusion, depen- can be managed by sufficient oxygen supply and in the divers’ improved health and in the reduction of transfer of O2 and CO2 from inhaled air occurs in the ding on the diffusion surface, the concentration hyperbaric chambers (with an initial compression, fatal consequences of the disease. Bert also discove- alveoli by simple diffusion. Its number is estimated at gradient on both sides of the membrane, membra- followed by gradual decompression). red that increasing of the pressure could reduce the about 500 million. Gas molecules have to overcome ne thickness and partial gas pressures. In a nor- Decompression sickness (caisson disease). During effects of the disease. In 1893, his proposal led to the the alveolar walls (the flat respiratory epithelium), mal situation, the pO2 of alveolar air is 13.3 kPa. an (especially a faster) ascent phase of scuba diving, construction of the first decompression chamber in the capillary wall (flat endothelial cells) and the cyto- Peripheral receptors in carotid and aortic bodies nitrogen dissolved in the body is released in the form

America (Oyhenart, 2004). Bert’s recommendati- plasmatic membrane of erythrocytes. The transport react to the decline already at a pO2 decrease to 7.3 of bubbles into bodily fluids. The bubbles mechani- on that divers ascend from depth more slowly has of breathing gases depends on the total surface of the kPa, which results in increased ventilation. Under cally compress and tear tissue, restricting circulation however not solved all problems experienced by di- alveoli (about 55–80 m2), the thickness of the alveo- normal conditions, however, the main stimulus in firm tissues, damage vascular walls and release vers. These issues still concerned divers at a depth of lar wall, as well as on the number of capillaries and for increased ventilation is the increase in carbon substances promoting blood clotting, block circula- more than 40 meters, irrespective of the duration of the degree of their blood supply. Gas diffusion thus dioxide, stimulating the inspiratory center in the tion in the venous system and embolize into lungs, submersion. In the years 1905-1907, English philo- corresponds to both the time during which blood is medulla oblongata. The higher the pCO2, the more have an affinity for fat tissue and thus even for the sopher J.S. Haldane conducted a number of experi- in contact with the air inside the alveoli (about 0.75 the breathing rate and the breathing volume incre- nervous tissue it surrounds. ments with divers of the Royal Navy and discovered s but also 0.3 s is sufficient) and to the difference in ase. The critical value is considered to be a pCO2 of DCS risk factors include age, gender, and the amount that the problem consisted in insufficient air venti- O2 pressure in the alveoli and in the blood that flows 6.6- 9.3 kPa, during which an opposing, narcotic of fat. The elderly, obese patients, and women with an lation of the divers’ helmets. The lack of ventilati- through the capillaries. The greater the O2 partial effect on the respiratory center occurs. In the blo- increased tendency for thrombus formation (relation influenced the concentration of carbon dioxide, pressure, the greater is the amount of O2 that binds od, oxygen binds mainly to hemoglobin (98.5 %), vely often associated with hormonal contraceptives) which was constantly causing gradual poisoning. to hemoglobin. Diffusion is however easier for CO2, while the rest is dissolved in plasma (1.5 %). Car- are at a higher risk. Genetic predisposition and men- Haldane recommended increasing the flow of air to as its concentration gradient is only 1 kPa in contrast bon dioxide is transported in a bicarbonate buffer strual phases (the first and last week of the menstrual the diver’s helmet in direct proportion to the pressu- to 8.5 kPa for O2. system, binding to carbonic acid (70 %), hemoglo- cycle, Lee 2003), as well as fatigue, cold, dehydration, re (depth) of the diver’s environment. He also pro- Higher pressure is one of the significant deviati- bin (23 %), while a small amount is freely dissol- and intercurrent disease also contribute to the risk duced a set of tables (see appendix), which determi- ons for the human organism in underwater envi- ved in plasma (7 %). Nitrogen, as an inert gas, is (Brubakk, 2003). ned the maximum length of diver‘s stay at a certain ronment. Hydrostatic pressure increases proportio- freely dissolved in plasma and does not cause any Currently, we distinguish two types of acute decom- depth. Furthermore, he developed a decompression nally with increasing depth. When scuba diving, the problems in daily life. Oxygen is crucial to life fun- pression sickness with the following symptoms: method at the ascent of the diver. In the following diver inhales air (or a gas mixture) that is under the ctions. For 1 liter of oxygen, 20-30 liters of air have • type I – unusual fatigue, muscle and bone pain, years, Haldane’s tables were adapted and modified, same pressure as the pressure in the surrounding en- to pass through the lungs in a resting position (Ga- rash, red and blue marbling, itching and lympha- while the basic principles are still used today for di- vironment. Although the percentage of gas content nong, 2005). At expiration, excess CO2 is expelled tic swelling of limbs and face vers’ ascent procedures. Haldane’s discoveries led to in inhaled air remains constant, the partial pressures by the lungs and alveoli by simple diffusion, as in • type II – dry cough, pain under the sternum, a shift of the maximum diving depth to 65 meters of each gas increases with increasing depth. At sea the case of oxygen. Common partial pressures in shock and CNS damage with loss of feeling, para- to which, at those times, it was possible to manually level, the pressure is approximately 1 atm, while at a arterial blood are pO2 10.0-13.3 kPa and pCO2 4.8- lysis, hallucinations, and convulsions (Bookspan, pump air (Willmshurst, 1998). depth of 10 meters, it is already 2 atm - every 10 me- 6.0 kPa.. From a clinical perspective, a significant 2005)

The deepest working dive was achieved to a depth of ters, pressure increases by 1 atm (Levett, 2008). decrease in pO2 is under 6.5 kPa and an increase in Symptoms develop from 5 minutes to 24 hours af-

534 meters (5494 kPa). The world record is however pCO2 at over 6.5 kPa (Cinglová, 2010). ter surfacing, most frequently after 1 hour (Joiner,

42 journal of outdoor activities Volume 7 No. 1/2013 ISSN 1802-3908 43 H. Kroehl died. Another situation reported in 1869 attributed to the COMEX Hydra 11 team. In 1992, Control respiration Specifics of gas behaviour in hyperbaric also resulted from diving activities, in which the di- the team achieved a depth of 701 meters at a pressure Breathing is controlled by neural and chemical enviroment ver used an air-filled helmet (Vrbovský et al., 1997). of 7181 kPa (Levett, 2008). mechanisms. Peripheral nervous control occurs During diving, hydrostatic pressure and temperature If the pressure decreased too fast, nitrogen was relea- in the lungs and is related with the stimulation of of the surrounding water changes, and it is thus ne- sed too quickly and bubbles formed within tissues of Physiology of respiration receptors during the inspiratory expansion of the cessary to accept gas behavior, subject to the laws of the body. They caused symptoms of divers’ disease, The composition of inhaled air corresponds to alveoli. This feedback stimulation inhibits the tone physics. ranging from itching, rashes, and joint pain to failure approximately 78 % of nitrogen (N), 21 % of oxygen of the inspiratory center and expiratory occurs, al- of sensory input, paralysis, and death. (O2), 1 % of rare gases and 0.03 % of carbon dioxide ternating rhythmically with inhalation. The respi- Nitrogen

534 meters (5494 kPa). The world record is however pCO2 at over 6.5 kPa (Cinglová, 2010). ter surfacing, most frequently after 1 hour (Joiner,

42 journal of outdoor activities Volume 7 No. 1/2013 ISSN 1802-3908 43 2001). Since it is not possible to anticipate how symp- • Inadequate pulmonary ventilation – occurs to insufficient supply. It can result from a primary and hypercapnia. In a healthy person, it can occur toms develop, it is necessary to begin with first aid mainly during heavy physical exertion with ina- oxygen deficiency (for example, when breathing air when drowning. It can arise when a diver is under as soon as the first symptoms appear and to rapidly dequate lung ventilation or during an improper with low oxygen content in a diving bell) or from stress and pulls his mouthpiece away, when he expe- transport the injured to the doctor. Decompression construction of lung mechanics, its damage, or inadequate breathing, or hypoventilation (e.g. du- riences convulsions and fails to hold the mouthpiece sickness therapy consists of supplying oxygen and in situations where the diver tries to conserve air ring a reduction effort). Another risk for divers is in his mouth, or when the gas in the diving cylinder performing a single, or more frequently, a repetitive (shallow breathing). however also deliberate or unconscious hyperven- is fully consumed. (up to 3x) compression and decompression sequence Use of breathing apparatus with helmet – here, the tilation. Conscious hyperventilation before immer- in a hyperbaric chamber, which lasts 5 hours on aver- concentration of CO2 can increase due to the accu- sion is related to the diver’s attempt to prolong the Other Diving Problems age (Dankner, 2005). mulation of expired air; the diver has to “rinse his dive, while unconscious hyperventilation appears Apart from pathological conditions, caused by Decompression sickness may however also be chro- helmet” every 5-10 minutes with regard to the diffi- during stress (anxiety, fear). Although it is most specific gas behavior, other problems may arise. nic. It can occur after suffering the acute form or culty and strenuousness of performed work common in beginners, it can even happen to expe- They are mainly caused by improper diving tech- even without previous occurrences. Its symptoms Malfunction of the CO2 absorber – this occurs when rienced divers in surprising situations, such as an niques during descent or ascent. During descent, include chronic bone and joint problems. Divers using a malfunctioning closed-circuit device, where encounter with a shark. Hyperventilation leads to an ear barotrauma can occur (mostly due to na- can also chronically suffer from neurocognitive CO2 accumulates in the breathing bag. an exhalation of a larger amount of CO2, leading to sopharynx and sinus inflammations or improper dysfunction, such as impaired memory or loss of Poor ventilation of enclosed spaces – can occur for its decline - hypocapnia. Hypocapnia reduces the diving techniques). When cold water enters the concentration, loss of hearing, and pulmonary di- example during medical or dry decompression, stimulation of the respiratory center in the medulla, inner ear during an eardrum rupture, a severe im- sorders (Brubbak, 2003). when the operator forgets to ventilate the space, so causes hypoventilation, and then hypoxia. First, we pairment of the vestibular system can occur. This

the exchange of vitiated air with high CO2 cannot can observe euphoria, later dyspnoea, cyanosis of state, known as the labyrinth crisis, manifests it- Carbon dioxide occur. the lips and nails, dizziness, and eventually collapse self in 1-2 minutes by vomiting and a dangerous

Carbon dioxide (CO2) is formed in tissues as the Warning signs of increased levels of CO2 in the body and loss of consciousness. This condition is known loss of orientation. At surfacing, nose bleeding, main metabolic waste product. It is transported in include accelerated respiratory and heart rate. Gene- as deep water blackout. Transport hypoxia arises teeth damage, or intestine perforation may hap- the blood to the lungs, where it is expelled from the ral discomfort, such as fatigue, weakness, mild musc- for example during carbon monoxide (CO) poiso- pen. When breath is held during the ascent, a pul- body. le twitching and headaches may occur. The onset of ning. It was recorded during gas cylinder filling as a monary barotrauma may occur (pneumothorax

Hypercapnia entails an increase of pCO2. If CO2 is these symptoms is directly dependent on the partial result of contaminated air supply from combustion and air embolism). Pulmonary injury represents not continuously expired, it begins to accumulate and pressure of CO2. At a pCO2 of up to 2 kPa, symp- engines. These cases of air contamination are howe- one third of all deaths, while two thirds are caused act as a poison. If a diver performs strenuous physical toms appear only rarely. In the range of 2 – 5 kPa, an ver luckily rare in recreational diving. The amount by drowning. (Cinglová, 2010) activity underwater, muscle tissues will produce CO2 increase in pulmonary ventilation occurs, while the of CO present is not dangerous at the water surface, faster than the respiratory tract can eliminate it. In- afflicted experiences shortness of breath. Between yet it can cause death at greater depths. Poisoning Discussion creased levels of carbon dioxide cause the respiratory 5 – 10 kPa, ventilation continues to increase, while begins with headaches, and the issues depend on The matter of diving is very broad and multiface- reflex center to stimulate a faster rate of breathing. changes in attention and judgment occur, reflexes the intensity of breathing. The half time for CO ex- ted and it is not possible to approach the issue in a Due to the denser inhaled air at depth, this requires slow down, and motor coordination and orientation pulsion lasts 3 – 4 hours. Oxygen treatment is the complex manner within the scope of one article. The considerable effort of the diaphragm and other respi- become impaired. At a pCO2 above 10 kPa, signifi- most common form of therapy (Cinglová, 2010). article only marginally addresses other health risks, ratory muscles to overcome resistance. This excessive cant changes in the activity of the central nervous Oxygen toxicity. Oxygen toxicity is a condition re- such as various barotrauma during descent (compre- respiratory effort further increases the production of system (CNS) occur, resulting in overall convulsions sulting from an elevation of pO2. It can occur when ssion) and the risks of pulmonary embolism or pne- carbon dioxide, which in turn again results in a hi- and loss of consciousness, called shallow water blac- an inappropriately combined gas mixture is used - umothorax at ascent (decompression). gher demand for faster breathing. These complicati- kout. Treatment consists of an immediate reduction for example breathing pure oxygen or using Nitrox Breathing mixtures are also a very specific issue. ons can be eliminated only in a situation, where the of CO2 partial pressure by oxygen administration or (a mixture of nitrogen and oxygen) at greater depths. The negative experiences with gas behavior gradu- diver stops or at least greatly reduces his physical ac- at least by ensuring a sufficient supply of fresh air. At The most frequently used is the combination of 32- ally led to the testing and preparation of various tivity. Only then can the respiratory system expel the a pulmonary or cardiac arrest, it is absolutely nece- 36 % of O2 and 84 % of N, but someone also raises the combinations (air, oxygen, helium, nitrogen, hyd- elevated levels of CO2 and provide a balanced gas ex- ssary to start rescue breathing and an indirect heart amount of oxygen to 40 %. Oxygen toxicity can ma- rogen, neon). In case of air respiration (with 21 % change. Hypercapnia can also be caused by an unsui- massage at a ratio 30: 2 in adults and 15: 2 in children nifest itself in nervous or pulmonary forms (Joiner, of O2), oxygen becomes toxic at around 60-70 me- table technique called “intermittent breathing.” In- (Levett, 2008). 2001). CNS toxicity is tolerated individually. Some ters. Pure oxygen can only be used safely in depths termittent breathing consists of breath-holding that Hypocapnia is a decrease of pCO2 < 4.8 kPa. It is of the symptoms are impaired coordination, tunnel to 12 meters, where significantly shorter decom- the diver uses during scuba diving to conserve air most often induced by hyperventilation. vision, ear ringing, mydriasis, dizziness, and halluci- pression stops are advantageous. Nitrox, Heliox and thus prolong the time spent underwater. In fact, nations. The risk increases with hard work, resistance or Trimix are currently the most widely used gas this technique causes an increase in carbon dioxide Oxygen breathing with an increased production of CO2, and mixtures. It turned out, however, that Nitrox (a in the circulatory system. This actually stimulates Oxygen (O2) is a prerequisite for survival on Earth. It during hypothermia. Pulmonary toxicity is typical combination of 36% of oxygen and nitrogen) is faster breathing and the air supply is consumed faster can however also have an adverse effect on the body, for more challenging diving operations. It manifests only suitable for shallower dives (up to 30-40 me-

(Pandergast, 2009). The most common causes of CO2 both in its lack (hypoxia), and in its abundance that itself with breathing difficulties, chest pain and pre- ters). During dives at depths below 120 meters, increase in the body and the recommendations for can be toxic (hyperoxia). ssure, coughing, and decreased ventilation capacity. divers suffer from a hyperbaric neurological syn- the reduction of hypercapnia are as follows: Hypoxia. During diving, hypoxia occurs when the Other symptoms include irritability, nausea, and drome (HPNS), with excitation symptoms, such as

• Excessive dead space – is mainly caused by a bre- values of pO2 in the blood drop below 6.5 kPa. Hy- convulsions (especially facial muscle spasms). tremors and myoclonic spasms. To eliminate the athing tube with too large dimensions. poxic hypoxia is a lack of oxygen in the blood due Asphyxia (suffocation) is a combination of hypoxia narcotic effect at depths, Trimix, a combination of

44 journal of outdoor activities Volume 7 No. 1/2013 ISSN 1802-3908 45 2001). Since it is not possible to anticipate how symp- • Inadequate pulmonary ventilation – occurs to insufficient supply. It can result from a primary and hypercapnia. In a healthy person, it can occur toms develop, it is necessary to begin with first aid mainly during heavy physical exertion with ina- oxygen deficiency (for example, when breathing air when drowning. It can arise when a diver is under as soon as the first symptoms appear and to rapidly dequate lung ventilation or during an improper with low oxygen content in a diving bell) or from stress and pulls his mouthpiece away, when he expe- transport the injured to the doctor. Decompression construction of lung mechanics, its damage, or inadequate breathing, or hypoventilation (e.g. du- riences convulsions and fails to hold the mouthpiece sickness therapy consists of supplying oxygen and in situations where the diver tries to conserve air ring a reduction effort). Another risk for divers is in his mouth, or when the gas in the diving cylinder performing a single, or more frequently, a repetitive (shallow breathing). however also deliberate or unconscious hyperven- is fully consumed. (up to 3x) compression and decompression sequence Use of breathing apparatus with helmet – here, the tilation. Conscious hyperventilation before immer- in a hyperbaric chamber, which lasts 5 hours on aver- concentration of CO2 can increase due to the accu- sion is related to the diver’s attempt to prolong the Other Diving Problems age (Dankner, 2005). mulation of expired air; the diver has to “rinse his dive, while unconscious hyperventilation appears Apart from pathological conditions, caused by Decompression sickness may however also be chro- helmet” every 5-10 minutes with regard to the diffi- during stress (anxiety, fear). Although it is most specific gas behavior, other problems may arise. nic. It can occur after suffering the acute form or culty and strenuousness of performed work common in beginners, it can even happen to expe- They are mainly caused by improper diving tech- even without previous occurrences. Its symptoms Malfunction of the CO2 absorber – this occurs when rienced divers in surprising situations, such as an niques during descent or ascent. During descent, include chronic bone and joint problems. Divers using a malfunctioning closed-circuit device, where encounter with a shark. Hyperventilation leads to an ear barotrauma can occur (mostly due to na- can also chronically suffer from neurocognitive CO2 accumulates in the breathing bag. an exhalation of a larger amount of CO2, leading to sopharynx and sinus inflammations or improper dysfunction, such as impaired memory or loss of Poor ventilation of enclosed spaces – can occur for its decline - hypocapnia. Hypocapnia reduces the diving techniques). When cold water enters the concentration, loss of hearing, and pulmonary di- example during medical or dry decompression, stimulation of the respiratory center in the medulla, inner ear during an eardrum rupture, a severe im- sorders (Brubbak, 2003). when the operator forgets to ventilate the space, so causes hypoventilation, and then hypoxia. First, we pairment of the vestibular system can occur. This the exchange of vitiated air with high CO2 cannot can observe euphoria, later dyspnoea, cyanosis of state, known as the labyrinth crisis, manifests it- Carbon dioxide occur. the lips and nails, dizziness, and eventually collapse self in 1-2 minutes by vomiting and a dangerous

44 journal of outdoor activities Volume 7 No. 1/2013 ISSN 1802-3908 45 oxygen, nitrogen, and helium is used, minimizing Conclusion České republiky. the problem (Talpar, 2006). The main objective of this article was to draw atten- Wilmshurst, P. (1998). Diving and oxygen. British Medical Journal. vol. 317, 996-999. The article does not address freediving, in which re- tion to one of the aspects crucial to scuba diving cords that are achieved surpass all previous theories – the specific behavior of breathing gases, subject Author: PhDr. Michal Mašek, email: [email protected] about the limits of human capabilities. This interes- to known physical laws. During scuba diving, it is ting theme deserves a special article. Nor does the always necessary to observe all safety precautions article discuss specific problems, such as diving at and recommendations. It is important to carefully higher altitudes or repeated dives, for which there prepare and plan the dive, to check the equipment are other special decompression tables. Repeated and to respect the planned schedule. The maximum dives imply a higher amount of accumulated nit- planned depth should not be exceeded, while an rogen, while dives at higher altitudes involve faster accompanying person should constantly monitor nitrogen saturation. Decompression tables are used the diver. The diver should also strictly adhere to for an altitude from 0 – 700 and 701 – 2 500 meters decompression (or safety) stops at ascent and en- above sea level. We should also expect that the body sure that, at surfacing, the diving cylinder still has is sensitive to subsequent changes in hydrostatic a pressure of at least 50 atm, which is ¼ of the total and atmospheric pressure. To avoid decompression pressure of a full diving cylinder. When respecting sickness, it is therefore also necessary to observe the these rules, diving can become a safe outdoor acti- prescribed time between the flight and the last dive vity that brings many beautiful experiences. (usually 6 hours after a single dive and 18 hours after repeated dives), since the pressure of a normal The research was funded by the research project aircraft cabin during a flight corresponds to the pre- MSM 00216 208 64, specific university research 2013 ssure at an altitude of approximately 2000 - 2 500 – 267 603 and the program for the development of meters above sea level. scientific disciplines at Charles UniversityP38 .

References Bennett, B.P., & Elliott, H.D. (1982). The Physiology and Medicine of Diving. London: Bailliere Tindall. Bookspan, J. (2005). Diving Physiology. Undersea & Hyperbaric Medical Society. Brubakk, A., Neuman, T., eds. (2003). Bennet and Elliott´s physiology and medicine of diving. 5th ed. London: Elsevier Science, Cinglová, L. (2010). Vybrané kapitoly z tělovýchovného lékařství. In Czech. Choice chapters from Sport Medicine. Praha: Karolinum. Dankner, R., Gall, N., Friedman, D. et al. (2005). Recompression treatment of Red Sea diving accidents: a 23 year summary. Clin J Sport Med. vol.15, 253-256. Ganong, W. (2005). Review of Medical Physiology. 22th ed. USA: McGrave-Hill Company. Hendl, J. (2007). Role přehledu ve vědě. In Czech. Role of Survey in Science. Česká Kinantropologie. roč. 11, 5-9. Joiner, J.T. (ed.) (2001). NOAA Diving. Manual-Diving for Science and Technology. 4th ed. Flagstaff: Best Publishing Co. Lee, V., St Leger D.M., Edge C. et al. (2003). Decompression sickness in women: a possible relation with the menstrual cycle. Aviat Space Environ Med. vol. 44, 1177-1182. Levett, D.Z.H., & Millar, I.L. (2008). Bubble trouble: a review of diving physiology and disease. Postgrad Med J. vol.84, 571-578. Oyhenart, J.M., & Mioulane P. (2004). Plongée-Passion et Mode ďEmploi. Czech translation. Potápění vášeň a profese. Praha: Euromédia Group k.s. Pendergast, D.R., & Lungren, C.E. (2009). The physiology and pathophysiology of the hyperbaric and diving environments. J Appl Physiol. vol.106, no.1, 274-275. Talpar, A.E., & Grossman, Y. (2006). CNS manifestation of HPNS: revisited. Undersea Hyperb Med. vol.33, 205-210. Vann, R.D., Freiberger, J.J., Caruso, J.L. et al. (2005). Report on decompression illness, diving fatalities and project diver exploration. DAN´s Review of Recreational Scuba Diving. Vrbovský, V. et al. (1997). Potápění s přístrojem. In Czech. Diving with apparatus. Praha: Svaz potápěčů

46 journal of outdoor activities Volume 7 No. 1/2013 ISSN 1802-3908 47 oxygen, nitrogen, and helium is used, minimizing Conclusion České republiky. the problem (Talpar, 2006). The main objective of this article was to draw atten- Wilmshurst, P. (1998). Diving and oxygen. British Medical Journal. vol. 317, 996-999. The article does not address freediving, in which re- tion to one of the aspects crucial to scuba diving cords that are achieved surpass all previous theories – the specific behavior of breathing gases, subject Author: PhDr. Michal Mašek, email: [email protected] about the limits of human capabilities. This interes- to known physical laws. During scuba diving, it is ting theme deserves a special article. Nor does the always necessary to observe all safety precautions article discuss specific problems, such as diving at and recommendations. It is important to carefully higher altitudes or repeated dives, for which there prepare and plan the dive, to check the equipment are other special decompression tables. Repeated and to respect the planned schedule. The maximum dives imply a higher amount of accumulated nit- planned depth should not be exceeded, while an rogen, while dives at higher altitudes involve faster accompanying person should constantly monitor nitrogen saturation. Decompression tables are used the diver. The diver should also strictly adhere to for an altitude from 0 – 700 and 701 – 2 500 meters decompression (or safety) stops at ascent and en- above sea level. We should also expect that the body sure that, at surfacing, the diving cylinder still has is sensitive to subsequent changes in hydrostatic a pressure of at least 50 atm, which is ¼ of the total and atmospheric pressure. To avoid decompression pressure of a full diving cylinder. When respecting sickness, it is therefore also necessary to observe the these rules, diving can become a safe outdoor acti- prescribed time between the flight and the last dive vity that brings many beautiful experiences. (usually 6 hours after a single dive and 18 hours after repeated dives), since the pressure of a normal The research was funded by the research project aircraft cabin during a flight corresponds to the pre- MSM 00216 208 64, specific university research 2013 ssure at an altitude of approximately 2000 - 2 500 – 267 603 and the program for the development of meters above sea level. scientific disciplines at Charles UniversityP38 .

46 journal of outdoor activities Volume 7 No. 1/2013 ISSN 1802-3908 47