practice practice divers comprises planning monitoring profile indicated tables chosen model allow harmless release excess gases dissolved tissues result breathing ambient pressures greater surface atmospheric pressure equipment available appropriate circumstances dive procedures authorized equipment profile large range options aspects 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 staged include deep stops depending theoretical model calculating ascent schedule omission theoretically required dive profile significantly higher risk sickness severe cases injury death risk related severity exposure level tissues procedures emergency management omitted sickness published procedures generally effective vary effectiveness case case procedures depend mode diving available equipment site environment actual dive profile standardized procedures developed provide acceptable level risk circumstances appropriate different sets procedures commercial military scientific recreational divers considerable overlap similar equipment concepts common procedures context diving derives reduction ambient pressure experienced ascent end dive exposure refers reduction pressure process allowing dissolved gases eliminated tissues reduction pressure descends water column ambient pressure rises breathing gas supplied pressure surrounding water gas blood gas continues taken gas dissolved state breathing gas lungs diving moves water column reduces ambient pressure breathing gas gases dissolved tissues higher concentration state start dissolved gases nitrogen form bubbles blood tissues partial pressures dissolved gases gets high ambient pressure bubbles products injury caused bubbles cause damage tissues known sickness bends immediate goal controlled avoid development symptoms bubble formation tissues long term goal avoid complications sub clinical injury common procedures descent time ascent sectors common descent rate descent rate generally allowed planning assuming maximum descent rate specified instructions use tables critical descent slower nominal rate reduces useful time adverse effect descent faster specified maximum expose greater rate earlier dive time reduced accordingly case real time monitoring dive computer descent rate specified consequences automatically accounted programmed time time time spent depth starting ascent time planning defined differently depending tables include descent time cases important check time defined tables example tables define time time leaving surface start final ascent metres minute ascent rate slower ascent time needs considered time remain safe ascent rate ascent important process time reduction ambient pressure occurs critical importance safe ascent rate compatible safe elimination gas tissues ascent rate limited prevent tissues extent unacceptable bubble development occurs usually maximum ascent rate compatible model chosen specified tables user manual software personal computer instructions usually include procedures specified rate delays exceeding recommended rate failure comply specifications generally increase risk sickness typically maximum ascent rates order metres minute deeper metres dive computers variable maximum ascent rates depending depth ascent rates slower recommended standard generally treated computer dive profile requirement adjusted accordingly faster ascent rates warning additional stop time compensate stop dive dive needs stops ascent according chosen tables relies controlled ascent rate elimination excess gases effect continuous ascent safety stop precaution unnoticed dive computer malfunction error sickness divers extra safety stop addition prescribed dive computer tables safety stop typically minutes metres usually stop added staged dive computers indicate recommended safety stop standard procedure specific limits depth time model significant risk reduction following safety stop low risk dive limit limit stop time interval theoretically spend given depth having perform stops helps divers plan stay given depth ascend stopping avoiding unacceptable risk sickness theoretical time obtained calculating gas release body model science calculating limits refined century unknown gases enter leave human body addition individual body unique absorb release gases different rates reason dive tables typically degree safety built recommendations divers suffer sickness remaining inside low range depths printed dive tables grid plan different tables available software programs limits personal computers dive computers indicate remaining limit current depth dive displayed interval continuously revised account changes depth time continuous continuous stops instead fairly rapid ascent rate stop followed period static depth stop ascent slower officially stopping theory profile practice difficult manually necessary stop ascent occasionally schedule stops schedule example treatment table referring treatment chamber type sickness states descent rate min ascent rate exceed min compensate slower ascent rates compensate faster rates halting ascent practice ascent rate vary depth typically faster greater depth reduces depth gets shallower practice continuous profile ascent steps small chamber pressure gauge resolve timed follow theoretical profile closely example treatment table sickness initial treatment compression chamber states stops feet times shown profile profile shows ascent rate min feet sea water followed hour hours staged follows procedure relatively fast ascent interrupted periods constant depth known staged ascent rate depth duration stops integral parts process advantage staged far easier monitor control continuous stops stop period spend relatively shallow constant depth ascent dive safely eliminate absorbed gases body tissues avoid sickness practice making stops called staged opposed continuous identifies requirement stops needed depths stops tables software planning tools dive computer ascent recommended rate reaches depth stop maintains specified stop depth specified period ascending stop depth recommended rate follows procedure repeated required completed reaches surface surface continue eliminate gas concentrations returned normal surface hours considered models effectively complete hours hours depth duration stop calculated reduce gas excess critical tissues concentration allow ascent unacceptable risk consequently dissolved gas stops shorter shallower high concentration length stops strongly influenced tissue compartments assessed highly saturated high concentrations slow tissues indicate longer stops similar concentrations fast tissues shorter shallower need single short shallow stop example minutes metres longer deeper need series stops stop longer shallower previous stop deep stops deep stop originally extra stop introduced divers ascent greater depth deepest stop required computer tables practice based observations technical divers found additional stops short periods depths considerably deeper calculated currently published recently computer claimed use deep stops available practice deep stops adequately deep stops likely depths continues slow tissues addition deep stops kind included dive profile schedule include slower tissues taken account deep stops added dive relies personal dive computer real time track effect stop schedule deep stops similar staged unlikely use dedicated gas usually minutes long study suggests addition deep shallow safety stop theoretically stop ascent significantly reduce stress indicated detected bubble levels authors associate gas exchange fast tissues spinal cord consider additional deep safety stop reduce risk spinal cord sickness recreational diving follow study found duration deep safety stop experimental conditions minutes shallow safety stop minutes longer safety stops depth reduce contrast experimental work comparing effect deep stops observed significant decrease bubbles following deep stop longer shallower increase bubble formation deep stop shorter deeper predicted existing bubble model controlled comparative study wet pot comparing deep stop profile suggests deep stops schedule greater risk matched total stop time conventional schedule proposed explanation slower gas continued gas offset benefits reduced bubble growth deep stops profile determined intermediate stops intermediate stops depth depth leading compartment calculation switches depth stop surface dive ambient pressure depth low ensure tissues gas small pressure gradient combination expected bubble growth leading compartment generally fastest compartment short model require intermediate stop compartment based model dive computer processes dive profile suggests intermediate minute stop function tissue nitrogen loading time taking account accumulated nitrogen previous logic model compartments prescribed depth minute half time compartments relatively high pressure gradient existing obligation increased stop mandatory stop considered substitute important shallow safety stop stop dive switching breathing gas mix ascent influence depth stop concept introduced schedule schedule specified ascent rate series increasingly shallower stops increasing amounts time performs gases body ascent surface reduce risk sickness dive phase large time spent underwater cases longer actual time spent depth depth duration stop dependent factors primarily profile depth time dive breathing gas mix interval previous dive altitude dive site depth duration stop dive computer tables dive planning computer software technical typically prepare schedule plan going deeper planned spending longer depth planned recreational divers rely personal dive computer allow avoid allowing considerable flexibility dive profile surface supplied normally diving supervisor control point monitors dive profile adjust schedule suit occur missed stops missing required stop increases risk developing sickness risk related depth duration missed stops usual causes missing stops having breathing gas complete stops accidentally losing control aim basic training prevent faults predictable causes missing stops diving suit failure cold water force choose sickness injury marine animal attack limit duration stops willing carry procedure dealing omitted stops described principle procedure allows presenting symptoms sickness complete omitted extra added deal bubbles assumed formed period ceiling violated divers returned depth treated sickness attempt omitted procedure risk considered unacceptable normal operational circumstances chamber available omitted managed chamber appropriate pressure following surface schedule treatment table develops symptoms chamber treatment started delay accelerated accelerated use breathing gases ascent lowered gas result increased oxygen fraction result greater gradient given ambient pressure consequently accelerated relatively low risk bubble formation oxygen commonly gases purpose oxygen rich blends dive oxygen rich blends dive reduce risk complications mitchell showed switch gas different proportion gas components possible component previously absent present lower fraction gas faster components eliminated gas resulting raising total tissue tension gases tissue exceed ambient pressure sufficiently cause bubble formation ambient pressure reduced time gas switch conclude breathing gas switches scheduled deep shallow avoid period maximum resulting oxygen use pure oxygen accelerated limited oxygen open circuit upper limit oxygen partial pressure generally accepted bar equivalent depth metres sea water water surface higher partial pressures routinely surface supplied diving operation military civilian contractors consequences oxygen considerably reduced secure breathing gas supply navy tables revision start water oxygen equivalent partial pressure bar chamber oxygen equivalent bar repetitive dive started tissues retain gas excess surface condition considered repetitive dive means required dive influenced divers history gas tissues result containing dissolved gas case fully dive need longer eliminate increased gas loading surface interval surface interval surface interval time sit time spent surface pressure dive gas present end dive eliminated tissues continues tissues surface pressures hours case navy air tables considered complete hours tables specify hours normal exposure require hours assume nitrogen time planned depth repetitive dive time calculated relevant provide equivalent gas loading gas surface interval called nitrogen time gas nitrogen added planned actual time equivalent total time derive appropriate schedule planned dive equivalent times derived gases calculations automatically personal diving computers based recent diving history reason personal diving computers shared divers switch computers sufficient surface interval hours cases days depending tissue model recent diving history user gas modeled tissues repetitive group designations tables generally based tissue considered table designers limiting tissue likely applications case minute tissue tables use minute tissue diving altitude atmospheric pressure decreases altitude effect absolute pressure diving environment important effect lower surface pressure requires longer dive profile second effect ascending altitude route nitrogen tissues local pressures means consider dive repetitive dive dive days navy diving manual provides repetitive group designations listed altitude changes change time surface interval according relevant table altitude cross described navy diving manual procedure based assumption model produce equivalent predictions pressure ratio sea level equivalent depth planned dive depth deeper actual dive altitude calculated proportion ratio surface pressure dive site sea level atmospheric pressure sea level equivalent depth actual depth altitude sea level pressure altitude stop depths corrected ratio surface pressures produce actual stop depths shallower sea level stop depths stop depth altitude stop depth sea level altitude pressure sea level values standard open circuit tables applicable constant oxygen partial pressure provided closed circuit tables sea level equivalent depth stops altitude stop depth adjusted compensate altitude altitude corrected tables common diving computers altitude setting selected user flying ascent altitude diving exposure reduced atmospheric pressure period dive gas levels stabilized atmospheric levels risk sickness rules safe ascent based extension model calculations desired altitude generally simplified fixed periods range extreme case exceptional exposure dive navy requires surface interval hours ascent altitude surface interval hours dive hours dive specified detailed surface interval requirements based highest repetitive group obtained preceding hour period given manual table specified altitudes commercial flights aircraft nominally dan flying diving workshop consensus guidelines recommended wait hours flying hours stop diving previous hours wait hours flying multi day unlimited stop diving wait hours flying required stops fly symptoms necessary obtain treatment dan later proposed simpler hour wait recreational diving objections grounds long delay result lost business island diving resorts risks flying diving low warrant blanket restraint diving workshop following recommendations flying recreational diving hour surface interval individuals took resort introductory experience hour surface interval certified divers unlimited number air multiple days substantially longer hours technical divers breathing mixes specific evidence concerning diving available recommendations apply flying altitude greater cabin pressure altitude equivalent feet meters nasa train underwater simulate occasionally need fly cabin altitudes exceeding feet meters training use exceed hours maximum depth maximum equivalent air depth nasa guidelines maximum dive minutes allow air oxygen surface intervals oxygen breathing surface intervals reduces time fly factor seven times compared air study military organization indicated oxygen effective means reducing risk places example peru plateau airport mountain passes thousand feet sea level travelling places diving lower altitude treated flying equivalent altitude diving specialised procedures surface surface procedure staged obligation chamber instead water reduces time spends water exposed environmental hazards cold water currents enhance safety chamber controlled comfortable environment oxygen greater partial pressure risk drowning lower risk oxygen operational advantage divers chamber new divers supplied diving panel operations continue delay typical surface procedure described navy diving manual water stop required surfaced directly required including stop completed water surfaced chamber minutes leaving depth water surface interval water chamber exceeds minutes penalty incurred indicates higher risk symptoms developing longer required case successfully nominal interval according schedule air tables surface oxygen partial pressure bar duration stop minutes revision tables chamber stage periods oxygen stop periods oxygen according schedule air breaks minutes taken end minutes oxygen breathing surface procedures described semi controlled accidents data collected north_sea shown overall sickness water surface similar surface tends produce times type water possible explanation final stage ascent bubbles produced stopped lung deck chamber diameter bubbles reduced sufficiently pass reach circulation arterial later lodging causing symptoms scenario proposed type recorded profile diving multiple repetitive diving dry bell dry closed diving bells pressure vessels human occupation deployed surface transport divers underwater workplace pressures greater ambient ambient pressure depth divers dive sealed transport surface generally takes place controlled internal pressure greater ambient recovery depth divers way chamber effect dry bell mobile chamber option diving storage pressure pressure habitat spread transfer divers habitat pressure transfer pressure stay shift end period tissue compartments reached given pressure breathing mixture continued exposure increase gas loading tissues point onwards required remains divers work live pressure long period end period risks associated limited single exposure principle led practice diving relative safety comfort habitat conservative profile risk bubble formation growth consequent injury tissues consequence procedures divers likely suffer sickness symptoms slowest tissues bounce divers likely develop bubbles faster tissues dive slow process rate typically ranges hour navy rates require partial pressure oxygen maintained possible exceed volume restrict risk fire rate exceeding minute followed stop average table ascent rate hours remaining hours split rest periods adaptation generally schedule stop time theoretically complete specified rate minutes complete surface minute avoid possibility losing door seal low pressure differential losing hour slow norwegian tables similar specifically allow start upward excursion partial pressure oxygen maintained bar rest stop hours specified night starting midnight procedure treating sickness reducing bubble size allowing gas bubbles dissolve slowly avoid formation growth bubbles eliminating gases breathing oxygen pressure air atmospheric air shown effective treatment minor symptoms historically depth relief pain bit deeper maintaining pressure bubbles dissolved performing slow surface pressure later air tables specific depths followed slow procedure superseded entirely oxygen treatment oxygen therapy evidence effectiveness therapy utilizing oxygen shown standard care treatment typical oxygen treatment schedule provides standard treatment periods minutes oxygen breathing followed periods minutes air breaks taken oxygen breathing reduce risk oxygen water chamber available reasonable period alternative water dive site water emergency treatment sickness sending underwater allow gas bubbles tissues causing symptoms resolve risky procedure travel nearest chamber time save victim life procedure high risk suffering unconscious stop breathing whilst water events result drowning injury subsequent rescue surface risks extent helmet face mask voice communications surface depth positively controlled having water standby attend undergoing treatment times principle water treatment treatment chamber water regarded risky avoided increasing evidence technical divers surface demonstrate mild symptoms water breathe pure oxygen depth feet period seek alleviate symptoms trend noted dan accident report report notes whilst reported incidents showed little success recognize calls attempted failed case successful called report event know successfully historically water usual method treating sickness remote areas procedures informal based operator experience air breathing gas available divers generally standard diving gear relatively safe procedure low risk drowning lost consciousness equipment types equipment help divers carry plan monitor mark underwater position act control aid position reference low visibility currents shortened accelerated breathing oxygen rich gas oxygen high partial pressure oxygen mixes create effect oxygen window gas carried divers cylinders cave divers return single route leave gas cylinders attached points surface supplied divers composition breathing gas controlled gas panel divers long obligations inside gas filled chambers water surface planning monitoring equipment planning monitoring includes tables surface computer software personal computers wide range choice stops needed particular dive profile reduce risk sickness occurring end dive generate schedules particular dive profile tables general use implemented dive computer software depending chosen range limits given depth gas vary considerably possible right wrong options considered correct risk developing greater longer shorter given depth dive tables tables data form printed cards allow divers determine schedule given dive profile breathing gas cases specify altitude range choice tables professional diving use generally organization employing divers recreational training usually prescribed agency recreational purposes generally free use range published tables matter modify suit software available personal computers model requirements user specified dive profiles different gas schedules generated software represent specific dive plan breathing gas usual generate schedule planned profile likely profiles personal dive computer small computer designed worn dive pressure electronic mounted pressure resistant housing programmed model gas loading tissues real time dive display allows critical data dive including maximum current depth duration dive data including remaining limit calculated real time dive dive computer keeps track gas loading tissue dive computers provide measure safety divers accidentally dive different profile originally planned dive computers provide necessary information safe ascent event limits exceeded use computers manage recreational dive standard use common scientific diving value surface supplied commercial diving restricted serve dive profile recorder controlling depth ascent rate critical aspect successful depth ascent rate monitored sufficiently accurately controlled practical water requires reasonable tolerance variation depth rate ascent monitored real time computer nominal profile affect risk items equipment assist accurate adherence planned profile allowing easily control depth ascent rate transfer control specialist personnel surface shot line rope float surface sufficiently heavy weight holding rope approximately vertical shot line float sufficiently support weight divers likely time recreational divers free choose lesser risk shot weight sufficient prevent lifting inflation dry suit sufficient sink float line taken configurations shot line control use purely visual reference hold positively control depth climb hand hand stop device recreational diving technical diving stops comfortable secure provide divers surface cover visual reference divers position consists horizontal bar bars suspended depth intended stops bars sufficient weight sufficient easily change depth turbulent water divers experience control problems surface marker reel line dive leader allow boat monitor progress dive group provide operator positive control depth remaining slightly negative float support slight allows line kept slight tension reduces risk reel store roll line usually slightly negative released hang float away delayed surface marker soft tube attached reel line end inflated water released float surface deploying line provides information surface ascend equipment commonly recreational technical divers requires certain level skill operate safely signal boat started ascent indicate problem technical diving diving stage known basket launch recovery system platform divers stand hoisted water lowered workplace hoisted return surface lift water equipment exclusively surface supplied professional divers requires fairly complex lifting equipment diving stage allows surface team manage hoisted controlled rate stopped correct depth stops allows divers rest ascent allows divers relatively safely lifted water returned deck wet bell open bell similar diving stage concept air space open water divers heads shelter ascent descent providing gases accelerate reducing partial pressure gas component breathing mixture accelerate concentration gradient greater given depth usually achieved increasing partial pressure oxygen breathing gas different gas counter complications differing rates lead net gain total dissolved gas tension tissue lead bubble formation growth sickness consequence partial pressure oxygen usually limited bar water divers bar water bar chamber navy tables surface stage cylinders cylinders stored divers return route containing emergency gas return route known marked similar cylinders carried divers route secure commonly mounted cylinders rings sides harness divers avoid breathing oxygen enriched gas excessive depths high risk oxygen prevent happening cylinders containing oxygen rich gases positively identifiable way marking maximum operating depth clearly possible surface supplied divers supplied gas mixture suitable accelerated connecting supply surface gas panel providing divers allows accelerated usually oxygen maximum depth surface supplied bounce divers provided suitable current depth mixture changed times descent ascent great depths closed circuit usually controlled provide fairly constant partial pressure oxygen dive set point reset richer mix effect partial pressure gases low safely dive absorption gas place elimination gases ascent surface specialised equipment available water exclusively surface supplied diving equipment deck chambers surface described previous section deck chambers fitted built breathing systems supply alternative breathing gas occupants usually oxygen discharge gas outside chamber chamber gas excessively enriched oxygen cause unacceptable fire hazard require frequent chamber gas usually air dry bell bounce great depths chamber ascent later board support vessel case necessary transfer deck chamber bell capable performing function relatively cramped bell usually small possible minimize weight deployment system spread typically comprises living chamber transfer chamber chamber commonly referred commercial diving diving bell military diving personnel transfer capsule personnel transfer capsule chamber diving bell elevator lift transfers divers system work site completion work mission diving team gradually atmospheric pressure slow system pressure rates metres metres day schedules vary process involves ascent time consuming comparatively risky process multiple normally associated multiple non bounce diving operations rescue unit provided emergency evacuation divers system platform immediate risk fire sinking allows divers clear immediate danger crew normally start soon possible launching teaching practice basic theory use tables theory component training commercial divers dive planning based tables practice field management significant work diving supervisor recreational divers trained theory practice extent agency training standard certification vary rudimentary overview sufficient allow avoid obligation entry level divers use way personal dive computers software tables advanced technical divers detailed understanding theory generally required commercial recreational divers practice techniques matter altogether recreational divers expected certification organizations allow short levels recreational divers technical commercial military scientific divers expected normal course sport occupation specifically trained appropriate procedures equipment relevant level certification significant practical theoretical training divers practice safe effective procedures selection use appropriate equipment
Decompression practice