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Decompression in the context of diving derives from the reduction in ambient pressure experienced by the diver during the ascent at the end of a dive or hyperbaric exposure and refers to both the reduction in pressure and the process of allowing dissolved inert gases to be eliminated from the tissues during this reduction in pressure. The first recorded experimental work related to decompression was conducted by Robert Boyle, who subjected experimental animals to reduced ambient pressure by use of a primitive vacuum pump. In the earliest experiments the subjects died from asphyxiation, but in later experiments signs of what was later to become known as decompression sickness were observed. Later, when technological advances allowed the use of pressurisation of mines and caissons to exclude water ingress, miners were observed to present symptoms of what would become known as caisson disease, the bends, and decmpression sickness. Once it was recognised that the symptoms were caused by gas bubbles, and that recompression could relieve the symptoms, further work showed that it was possible to avoid symptoms by slow decompression, and subsequently various theoretical models have been derived to predict safe decompression profiles and treatment of decompression sickness. The symptoms of decompression sickness are known to be caused by damage resulting from the formation and growth of bubbles of inert gas within the tissues and by blockage of arterial blood supply to tissues by gas bubbles and other emboli consequential to bubble formation and tissue damage. The precise mechanisms of bubble formation and the damage they cause has been the subject of medical research for a considerable time and several hypotheses have been advanced and tested. Tables and algorithms for predicting the outcome of decompression schedules for specified hyperbaric exposures have been proposed, tested, and used, and usually found to be of some use but not entirely reliable. Decompression remains a procedure with some risk, but this has been reduced and is generally considered to be acceptable for dives within the well tested range of commercial, military and recreational diving. When a diver descends in the water column the ambient pressure rises. Breathing gas is supplied at the same pressure as the surrounding water, and some of this gas dissolves into the diver's blood and other tissues. Inert gas continues to be taken up until the gas dissolved in the diver is in a state of equilibrium with the breathing gas in the diver's lungs, (see: "Saturation diving"), or the diver moves up in the water column and reduces the ambient pressure of the breathing gas until the inert gases dissolved in the tissues are at a higher concentration than the equilibrium state, and start diffusing out again. Dissolved inert gases such as nitrogen or helium can form bubbles in the blood and tissues of the diver if the partial pressures of the dissolved gases in the diver gets too high when compared to the ambient pressure. These bubbles and products of injury caused by the bubbles, can cause damage to tissues known as ''decompression sickness'' or ''the bends''. The immediate goal of controlled decompression is to avoid development of symptoms of bubble formation in the tissues of the diver, and the long-term goal is to also avoid complications due to sub-clinical decompression injury. == Timeline == * 1660 – Sir Robert Boyle conducted an experiment on a bird in an air pump. This predates actual intentional investigations into decompression, but the experiment was effectively a rapid decompression and caused the death of the bird by asphyxiation. * 1670 – Sir Robert Boyle performed an experiment with a viper in a vacuum. A bubble was observed in its eye and it displayed signs of extreme discomfort. This was the first recorded description of decompression sickness. * 1841 – Jacques Triger documented the first cases of decompression sickness in humans when two miners involved in pressurised caisson work developed symptoms.〔 * 1847 – The effectiveness of recompression for treatment of DCS in caisson workers was described by Pol and Watelle.〔〔 * 1857 – Felix Hoppe-Seyler repeated Boyle's experiments and suggested that sudden death in compressed air workers was caused by bubble formation, and recommended recompression therapy. * 1868 – Alfred Le Roy de Méricourt described decompression sickness as a sponge divers' occupational illness.〔 * 1873 – Dr. Andrew Smith first used the terms "caisson disease" and "compressed air illness", describing 110 cases of decompression sickness as the physician in charge during construction of the Brooklyn Bridge.〔 The nickname "the bends" was used after workers emerging from pressurized construction on the Brooklyn Bridge adopted a posture similar to fashionable ladies of the period "the Grecian Bend".〔 * 1878 – Paul Bert determined that decompression sickness is caused by nitrogen gas bubbles released from tissues and blood during or after decompression, and showed the advantages of breathing oxygen after developing decompression sickness. * 1897 – N. Zuntz proposed a perfusion-based tissue model.〔Zuntz, N. (1897); ''Zur Pathogenese und Therapie der durch rasche Luftdruck-änderungen erzeugten Krankheiten'', Fortschr, d. Med. 15, 532–639〕 * 1906 – V. Schrotter suggested a uniform decompression of 20 minutes per atmosphere of pressure. J.S. Haldane was commissioned by the British Admiralty to study decompression sickness.〔 * 1908 – John Scott Haldane prepared the first recognised decompression table for the British Admiralty. This table was based on experiments performed on goats using an end point of symptomatic DCS.〔 * 1912 – Chief Gunner George D. Stillson of the United States Navy created a program to test and refine Haldane's tables. This program ultimately led to the first publication of the United States Navy Diving Manual and the establishment of a Navy Diving School in Newport, Rhode Island. Diver training programs were later cut at the end of World War I. * 1912 – Leonard Erskine Hill – continuous uniform decompression〔 * 1927 – Naval School, Diving and Salvage was re-established at the Washington Navy Yard. At this time the United States moved their Navy Experimental Diving Unit (NEDU) to the same naval yard. In the following years, the Experimental Diving Unit developed the US Navy Air Decompression Tables which became the accepted world standard for diving with compressed air.〔(【引用サイトリンク】title=Diving in the U.S. Navy: A Brief History )〕 * 1930's – Hawkins, Schilling and Hansen conducted extensive experimental dives to determine allowable supersaturation ratios for different tissue compartments for Haldanean model. * 1935 – Albert R. Behnke ''et al.'' experimented with oxygen for recompression therapy.〔 * 1937 – US Navy 1937 tables published (Yarborough)〔 * 1941 – Altitude DCS is treated with hyperbaric oxygen for the first time. * 1956 – US Navy Decompression Tables (1956) published * 1960 – FC Golding ''et al.'' split the classification of DCS into Type 1 and 2. * 1965 – LeMessurier and Hills paper on ''A thermodynamic approach arising from a study on Torres Strait diving techniques'' which suggests that decompression by conventional models results in bubble formation which is then eliminated by re-dissolving at the decompression stops, which is slower than elimination while still in solution, thus indicating the importance of minimising bubble phase for efficient gas elimination.〔LeMessurier and Hills. (1965) ''Decompression Sickness. A thermodynamic approach arising from a study on Torres Strait diving techniques''. Hvalradets Skrifter, Nr. 48, 54–84.〕 * 1965 – French Navy GERS (Groupe d'Etudes et Recherches Sous-marines) 1965 table * 1965 – Goodman and Workman – Introduction of recompression tables utilizing oxygen to accelerate elimination of inert gas〔How, J., West, D. and Edmonds, C. (1976); ''Decompression sickness and diving'', Singapore Medical Journal, Vol. 17, No. 2, June 1976.〕 * 1972 – Royal Navy Physiological Laboratory (RNPL) tables based on Hempleman's tissue slab diffusion model. * 1973 – Isobaric counterdiffusion first described by Graves, Idicula, Lambertsen, and Quinn in subjects who breathed one inert gas mixture while being surrounded by another.〔Graves, DJ; Idicula, J; Lambertsen, Christian J; Quinn, JA (February 1973). "Bubble formation in physical and biological systems: a manifestation of counterdiffusion in composite media". ''Science'' 179 (4073): 582–584. . PMID 4686464. http://www.sciencemag.org/cgi/pmidlookup?view=long&pmid=4686464. Retrieved 10 January 2010.〕〔Graves, DJ; Idicula, J; Lambertsen, Christian J; Quinn, JA (March 1973). "Bubble formation resulting from counterdiffusion supersaturation: a possible explanation for isobaric inert gas 'urticaria' and vertigo". Physics in medicine and biology 18 (2): 256–264. . PMID 4805115. http://stacks.iop.org/0031-9155/18/256. Retrieved 10 January 2010.〕 * 1973 – French civilian ''Tables du Ministère du Travail 1974'' (MT74) * 1976 – The sensitivity of decompression testing increased by the use of ultrasonic methods which can detect mobile venous bubbles before symptoms of DCS emerge. * 1981 – Huggins model and tables using Spencer's formula for no-decompression limits. * 1982 – Paul K Weathersby, Louis D Homer and Edward T Flynn introduce survival analysis into the study of decompression sickness. * 1983/4 – Albert A. Bühlmann publishes ''Decompression–Decompression sickness''.〔 Bühlmann recognized the problems associated with altitude diving, and proposed a method which calculated maximum nitrogen loading in the tissues at a particular ambient pressure. * 1984 – DCIEM (Defence and Civil Institution of Environmental Medicine, Canada) release No-Decompression and Decompression Tables based on Kidd/Stubbs serial compartment model and extensive ultrasonic testing. * 1984 – Edward D. Thalmann publishes USN E-L algorithm and tables for constant PO2 Nitrox closed circuit rebreather applications * 1985 – Thalmann extends use of E-L model for constant PO2 Heliox CCR. * 1985 – Bassett tables (based on USN Tables) * 1986 – Swiss Sport Diving Tables based on Bühlmann model〔 * 1986 – D. E. Yount and D. C. Hoffman propose a bubble model. * 1988 – BSAC'88 tables * 1990 – DCIEM sport diving tables released. * 1990 – French Navy – ''Marine Nationale 90'' (MN90) decompression tables * 1991 – D.E. Yount describes Varied Permeability Model * 1992 – French civilian Tables du Ministère du Travail 1992 (MT92) * 1999 – NAUI Trimix and Nitrox tables based on RGBM model * 2001 – NAUI recreational air tables based on RGBM model * 2003 – VPM-B model by Erik Baker, is the final revision to work from the DecoList (1999) participants, Eric Maiken, D.E. Yount and others. * 2007 – Gerth & Doolette publish VVal 18 and VVal 18M parameter sets for tables and programs based on the Thalmann E-L algorithm, and produce an internally compatible set of decompression tables for open circuit and CCR on air and Nitrox, including in water air/oxygen decompression and surface decompression on oxygen. * 2007 – S. Goldman proposes an Interconnected Compartment Model (3 compartment series/parallel model) using a single risk bearing active tissue compartment and two non-risk bearing peripheral compartments which indirectly affect risk of the central compartment. This model predicts initially fast gas washout which slows with time. * 2008 – US Navy Diving Manual Revision 6 includes a version of the 2007 tables by Gerth & Doolette. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「History of decompression research and development」の詳細全文を読む スポンサード リンク
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