diving reduction ambient pressure experienced ascent depth process elimination dissolved gases body occurs ascent ascent known stops gas concentrations reach divers breathing gas ambient pressure need ascend rate determined exposure pressure breathing gas use gas atmospheric pressure free diving usually need divers atmospheric diving suit need exposed high ambient pressure descends water pressure ambient pressure rises breathing gas supplied ambient pressure gas blood transferred blood tissues gas nitrogen continues taken gas dissolved state breathing gas lungs point saturated depth breathing mixture depth pressure changed ascent ambient pressure reduced stage gases dissolved given tissue higher concentration state start pressure reduction sufficient excess gas form bubbles lead sickness possibly life threatening condition essential divers manage avoid excessive bubble formation sickness usually results reducing ambient pressure quickly gas solution eliminated safely bubbles block arterial blood supply tissues directly cause tissue damage effective present eliminated body beds lungs given time bubbles created eliminated safely bubbles grow size number causing symptoms injuries sickness immediate goal controlled avoid development symptoms bubble formation tissues long term goal avoid complications sub clinical injury mechanisms bubble formation damage bubbles cause subject medical research considerable time advanced tested tables predicting outcome schedules specified proposed tested cases superseded constantly refined generally considered reliable actual outcome individual remains slightly unpredictable retains risk generally considered acceptable tested range normal recreational professional diving currently popular procedures advise safety stop additional stops required usually minutes metres continuous stop ascent continuous staged staged interrupted stops calculated depth intervals entire ascent actually ascent rate critical harmless elimination gas dive accurately dive stop relies limiting ascent rate avoidance excessive bubble formation time surface pressure immediately dive important thought stop dive hours body return normal atmospheric levels gas dive time spent surface known surface interval considered calculating requirements subsequent dive theory theory study modelling transfer gas component breathing gases gas lungs tissues exposure variations ambient pressure case underwater diving compressed air work involves ambient pressures greater local surface pressure high altitude occupants aircraft exposed ambient pressures standard sea level atmospheric pressure cases symptoms sickness occur relatively short period hours occasionally days significant reduction ambient pressure physics physiology absorption gases depends specific gas specific liquid concentration gas expressed partial pressure temperature main variable study theory pressure dissolved distribution dissolved gas bulk flow case blood circulated body gas local regions lower concentration given sufficient time specific partial pressure breathing gas concentration tissues rate depends rate vary different tissues body process referred usually modeled process concentration gas breathing gas reduced tissues tendency gas return tissues breathing gas known occurs reduction ambient pressure reduces partial pressure gas lungs process complicated formation gas bubbles modeling complex varied combined concentrations gases given tissue depend history pressure gas composition conditions total concentration dissolved gases ambient pressure oxygen tissues carbon dioxide produced reduction ambient pressure rate pressure reduction exceed rate gas eliminated concentration gets high reach stage bubble formation occur tissues pressure gases bubble exceed combined external pressures ambient pressure surface tension bubble liquid interface bubbles grow growth damage tissue dissolved gases come solution tissues body form bubbles cause condition known sickness known divers disease bends disease bubbles result symptoms bubble detection shows bubbles present significant number divers relatively mild bubbles form migrate body produce symptoms effects vary joint pain death individual vary day day different individuals conditions affected differently classification types symptoms evolved original description risk sickness diving managed effective procedures contracting uncommon remains degree unpredictable potential severity driven research prevent divers universally use tables dive computers limit monitor exposure control ascent speed procedures contracted usually treated oxygen therapy chamber treated early significantly higher chance successful recovery gas atmospheric pressure free diving usually need possible sickness repetitive deep free diving short surface intervals models actual rates gases specific tissues generally known vary considerably mathematical models proposed approximate real situation greater lesser extent models predict bubble formation likely occur given dive profile based models produce tables personal dive computers produce real time estimate status display different concepts modelling assumes dissolved gas eliminated dissolved phase bubbles formed second supported experimental observation assumes bubbles formed gas elimination consider dissolved bubble phases early models tended use dissolved phase models adjusted factors derived experimental observations reduce risk bubble formation main groups dissolved phase models parallel compartment models compartments varying rates gas absorption half time considered exist independently limiting condition controlled compartment shows worst case specific exposure profile compartments represent conceptual tissues don represent specific organic tissues merely represent range possibilities organic tissues second group uses serial compartments assumes gas compartment reaches recent models attempt model bubble dynamics usually simplified models facilitate tables later allow real time predictions dive models approximate bubble dynamics varied range complex dissolved phase models require considerably greater power practice practice divers comprises planning monitoring profile indicated tables chosen model equipment available appropriate circumstances dive procedures authorized equipment profile large range options aspects cases practice takes place framework system extra constraints behaviour constraints include limiting ascent rate making stops ascent additional stops limiting number performed day limiting number days diving week avoiding dive profiles large numbers avoiding heavy work immediately dive diving prior flying ascending altitude organizational requirements procedures continuous staged ascent interrupted stops regular depth intervals entire ascent ascent rate critical harmless elimination gas commonly known diving accurately stop relies limiting ascent rate avoidance excessive bubble formation procedures depend mode diving available equipment site environment actual dive profile standardized procedures developed provide acceptable level risk appropriate circumstances different sets procedures commercial military scientific recreational divers considerable overlap similar equipment concepts common procedures normal diving procedures range continuous ascent stop necessary occurs ascent kept controlled rate purpose staged open water bell generally occurs chamber system accelerated use breathing gases provide increased concentration differential gas components breathing mixture acceptable oxygen content medical procedure treatment sickness followed usually relatively conservative schedule equipment equipment directly associated includes tables software plan dive equipment control monitor depth dive time personal dive computers depth shot lines surface marker diving stages wet dry bells deck chambers treatment chambers supply gases carried supplied surface bell supplied chamber surface history research development symptoms sickness caused damage formation growth bubbles gas tissues arterial blood supply tissues gas bubbles bubble formation tissue damage precise mechanisms bubble formation damage cause subject medical research considerable time advanced tested tables predicting outcome schedules specified proposed tested usually found use entirely reliable remains procedure risk reduced generally considered acceptable tested range commercial military recreational diving early developments recorded experimental work related conducted subjected experimental animals reduced ambient pressure use primitive vacuum pump earliest experiments subjects died later experiments signs later known sickness observed later technological advances allowed use mines exclude water miners observed present symptoms known disease compressed air illness bends sickness recognized symptoms caused gas bubbles compression relieve symptoms showed sickness caused nitrogen bubbles released tissues blood showed advantages breathing oxygen developing sickness work showed possible avoid symptoms slow subsequently theoretical models derived predict safe profiles treatment sickness start systematic work models prepared recognized table british admiralty based extensive experiments goats end point united_states_navy tested refined tables research led publication united_states navy diving manual establishment newport rhode_island time working system continuous uniform established moved venue following years developed accepted world standard diving compressed air 1930s conducted extensive experimental determine different tissue compartments model experimented oxygen compression therapy navy tables published altitude sickness treated oxygen revised navy tables published beginnings alternative models hills published approach arising study diving techniques suggests conventional models forms bubbles eliminated stops slower elimination solution indicates importance bubble phase efficient gas elimination marines published tables introduced compression tables oxygen accelerate elimination gas published tables based tissue slab model subjects gas mixture surrounded described graves quinn french government published tables sickness testing sensitivity improved methods detect mobile bubbles symptoms apparent approaches developed introduced survival analysis study sickness published sickness recognized problems associated altitude diving proposed method calculated maximum nitrogen loading tissues particular ambient pressure modifying increase depth canada released based serial compartment model extensive testing published tables constant closed circuit applications extended use model constant model interpreted bubble model based model tables bubble models started prevalent proposed bubble model tables based bubble model sport diving tables based fitting experimental data model french navy marine tables development earlier model tables described development earlier bubble model varied model french civilian bubble model interpretation published tables based reduced gradient bubble model model followed recreational air tables based model published sets tables programs based produce internally compatible set tables open circuit air including water air oxygen surface oxygen included version tables developed
Decompression (diving)