创伤失血性休克研究与治疗的一些进展课件

AnesthesiaMachine SecondMedicalCollege三峡大学仁和医院JianDao lin简道林 Overview Thegasdeliverysystem Breathingsystems Anesthesiaventilator Safetyfeatures Scavenging Gasanalysis Accessories Newgenerationanesthesiamachines Definition Anesthesiologistsdefinethemachinewhichisusedtosupporttheadministrationofanesthesiaastheanesthesiamachine TheoriginalconceptwasinventedbytheBritishanesthetistH E G Boylein1917 Priortothistime anesthetistsoftencarriedalltheirequipmentwiththem butthedevelopmentofheavy bulkycylinderstorageandincreasinglyelaborateairwayequipmentmeantthatthiswasnolongerpracticalformostcircumstances Overview Thefunctionoftheanesthesiamachineistoprepareagasmixtureofpreciselyknownbutvariablecomposition Themachineprovidesacontrolledflowofoxygen nitrousoxide air andanestheticvapors Thesearedeliveredtoabreathingsystem whichprovidesameanstodeliverpositivepressureventilationandtocontrolalveolarcarbondioxidebyminimizingrebreathingand orbyabsorbingcarbondioxide Amechanicalventilatorisconnectedtothebreathingsystem freeinguptheanesthetist shandsforothertasks Severaltypesofmonitorsareusedtoobservethefunctionofthesystem todetectequipmentfailures and toprovideinformationaboutthepatient MadeinChina DragerNarkomed2A OhmedaAestiva ADatexOhmedaBritishmachine Thecommonesttypeofanaestheticmachineinuseinthedevelopedworldisthecontinuous flowanaestheticmachine whichisdesignedtoprovideanaccurateandcontinuoussupplyofmedicalgases suchasoxygenandnitrousoxide mixedwithanaccurateconcentrationofanestheticvapour suchasisoflurane anddeliverthistothepatientatasafepressureandflow Modernmachinesincorporateaventilator suctionunit andpatient monitoringdevices Aschematicdiagramofananesthesiamachine Non rebreathingSystems rebreathingsystem Vaporizer in the Circle rebreathingsystem Vaporizer out of the Circle Thegasdeliverysystem Oxygensupply Pipedgases Flowcontrolvalves Flowmeters Vaporizers Thecommongasoutlet Oxygenflushvalve 1 CentraloxygensupplysystemLiquidoxygen Oxygensupply 2 Oxygenbank smalleroxygencylindersortanks Pipedgases Walloutletssupplyoxygen nitrousoxideandairatapressureof50to55pounds in2 psi Theseoutletsandthesupplyhoses corrugatedtube tothemachinearediameterindexedandcolor coded Outletofcentraloxygensupplysystem 1 Afullcylinderofoxygen insizeE hasapressureof2 000to2 200psiandcontainstheequivalentof660Lofgasatatmosphericpressureandroomtemperature Theoxygencylinderpressuredecreasesindirectproportiontotheamountofoxygeninthecylinder 1 psi poundpersquareinch 6 895 kPa 0 0703 kg cm2 0 0689 bar 0 068大气压 atm 1 mmH2O 9 80665帕 Pa 1 mmHg 133 322 Pa 2 Afullcylinderofnitrousoxide insizeE hasapressureof745psiandcontainstheequivalentof1 500Lofgasatatmosphericpressureandroomtemperature Thenitrousoxideinthecylinderisaliquid thecylinderpressuredoesnotdecreaseuntiltheliquidcontentisexhausted atwhichtimeone fourthofthetotalvolumeofgasremains 3 Aircylinders insizeE arepresentonsomemachines Afullcylinderhasapressureof1 800psiandcontainstheequivalentof630Latatmosphericpressureandroomtemperature Aregulatororpressurereducingvalveonanesthesiamachinesreducesthecylinderpressureto50psi Ifthisvalvewerenotpartoftheanesthesiamachine thepressureofthegasenteringthemachinewouldbethesameasthepressureinthecylinder Theindustrystandardforpressurewithintheanesthesiamachinehasbeensetat50psi Theregulatorsdividethemachineintohigh pressure proximaltotheregulator andlow pressure distaltotheregulator systems Aregulatororpressurereducingvalve Flowcontrolvalves Aneedlevalvecontrolstheflowofeachgas Asasafetyfeature theoxygencontrolknobisflutedandprotrudesmorethanthenitrousoxideandaircontrols Gaspressuresarereducedfrom45to55psi highpressure tonearatmosphericpressure lowpressure by theneedlevalves Aregulatororpressurereducingvalve Oxygenflowcontrolvalve Asgasflowsoutofthelow pressurechamber thedropinpressurereducestheforcegeneratedbythediaphragm D againstthespring S allowingthevalve V toopenandadmitgasfromthehigh pressurechamber Theoutputpressuremaybeadjustedbyascrew A thatalterstheforceappliedbythespring Figure Cross sectionalviewofaneedlevalve Needlevalvesaresimilarindesignandoperationtotheglobevalve Insteadofadisk aneedlevalvehasalongtaperedpointattheendofthevalvestem Whenthelongtaperofthevalveelementisclock wiseturned thevalveisopened Contrarily thevalveisclosed Across sectionalviewofaneedlevalveisillustratedinfigure flowmeters Flowmeters Eachflowmeterisacalibratedtaperedglasstubeinwhichabobbinorballfloatstoindicatetheflowofgas Inotherwords Flowmeterscanbeofvaryingstyleshowevermostanesthesiamachineshaveflowmetersthatuseabobbinthatfloatsonacolumnofgastodeterminetheamountofflow Theneedlevalveisthemostcommonmeansofregulatinggasflowrate Asthevalveisopened theorificearoundtheneedlebecomeslargerandflowincreases Thevalvecartridgeitselfisusuallyremovablesoitcanbereplacedifitisdamaged Thevalvemustnotbeover tightened thiswilldrillouttheorificeandcauseittobecomeincompetent Somevalves suchasarefoundonmostmedicalanestheticmachines incorporateastoptopreventthevalvebeingover tightened Thevalvecontrolknobisusuallycolor coded Inaddition oxygenflowmeterknobsfrequentlyhaveflutededgestodistinguishthemfromthoseofothergases Theinsideofglassclinderbecomeswiderasthebobbinfloatshigherinthecylindertherebyallowingmoregastoflowupthetubeandoutoftheflowmeter Theflowmeterallowstheoperatortocontrolandknowtheflowrateofeachgas usuallyinlitersperminuteormLperminute Consistsofafloat usuallyalittleballinsideatube Itisusuallyreadfromthecenteroftheballandusuallycolorcoded likethegastanks Flowmetersareusedtocontroltheflowofagas oxygenusually whichisbeingdeliveredtothecircle Astheindicatororfloatoftheflowmeterrisesinthetube moregasflowsaroundit Somemachineshavetwoflowmeters oneforhighflowandoneforlowflowofoxygen Gas oxygen nitrousoxide usuallyentersatthebottom travelsthroughataperedtube andthenexitsatthetop Whenthevalveisclosed itshouldbeturnedonlyuntiltheflowofgasceasesasfurthertighteningmayresultindamagetothepinorseat Whenthemachineisnotused theflowcontrolknobsshouldbeopeneduntilthegaspressureiszero thenclosed Beforeusingamachine theflowmetersshouldbecheckedtoseeiftheyareintheclosedposition Iftheyhavebeleftopen whenthegassupplytoanopenflowcontrolvalveisrestored theindicatormayrisetothetopofthetubewhereitspre sensemaynotbenoticed Averyhighoxygenflowmayresult Vaporizers Ananestheticvaporiserisadevicegenerallyattachedtoananestheticmachinewhichdeliversagivenconcentrationofavolatileanestheticagent Thedesignofthesedevicestakesaccountofvaryingambienttemperaturefreshgasflowagentvaporpressure Vaporizer in the Circuit Vaporizer out of the Circuit Vaporizer out of the Circuit Thepurposeofananestheticvaporizeristoproduceacontrolledandpredictableconcentrationofanestheticvaporinthecarriergaspassingthroughthevaporizer Mostvaporizersareoftheplenumtype whichconsistsofavaporizingchambercontainingtheliquidanesthetic andabypass Gaspassingthroughthevaporizingchambervolatilizestheanestheticandisthenmixedwiththeanesthetic freegasbypassingthechamber theproportionofvapor containinggasandbypassgasbeing controlledbyatap Thecommongasoutlet Thecommongasoutletistheportwheregasesexitthemachineandisconnectedtothebreathingsystemviathefreshgashose Oxygenflushvalve Thisvalveallowsahighflowoxygentogodirectlytothebreathingsystemwithoutgoingthroughavaporizer usually Onehundredpercentoxygenat45to55psicomesdirectlyfromthehighpressuresystemtothecommongasoutlet Oxygenflowcanbeashighas40to60L min Breathingsystems ThedeliverysystemswhichconductanestheticgasesfromananestheticmachinetothepatientareknownasthebreathingsystemsorcircuitsTheyaredesignedtoalloweitherspontaneousrespirationorintermittentpositivepressureventilation IPPV andconsistofareservoirbag anesthetictubing andapressurereliefvalve Anumberofmechanicalventilatorsincludeaspecificbreathingsystem Otherventilatorshavebeendesignedtooperatewithexistingbreathingsystems Anestheticgasexitstheanesthesiamachine viathecommongasoutlet andthenentersabreathingcircuit Thefunctionofthecircuitistodeliveroxygenandanestheticgasestothepatientandtoeliminatecarbondioxide Thecarbondioxidemaybeeliminatedbygasinfloworbysodalimeabsorption Classificationofbreathingsystems Thecarbondioxideabsorber Twoone wayvalves inspiratoryandexpiratory BreathingHosesandY pieceadapter Reservoirbag APL adjustablepressure limitingvalve valveorpop offvalve Classificationofbreathingsystems Variousclassificationsystemshavebeendevelopedtoaidunderstandingofhowbreathingsystemsoperate Classificationofbreathingsystemsarefollowedas 1Open semi open semi closed andclosedbreathingsystem 2Non rebreathingandrebreathingsystems 1Open semi open semi closed andclosedbreathingsystem Thisclassificationismademainlyaccordingtotheconcentrationvalueofre breathingcarbondioxide Theboundaryconcentrationvalueofre breathingcarbondioxideis1percent Unfortunately indifferentpartsoftheworld thesameterminologyisusedfordifferentsystems sothisclassificationisprobablybestvoided 1 Opensystems Opensystemshavenovalves notubing forexampleopendropether oranasalcannula Ineither thepatienthasaccesstoatmosphericgases Thereisnotanyre breathingofcarbondioxide 2 Semi opensystem Semi opensystemreferstothatinwhichtheconcentrationofre breathedcarbondioxideislessthan1percent Semi opensystemshouldbenore breathingandmusthavehighfreshgasflowandhigherminuteventilation 3 Semi closedsystem Semi closedsystemreferstothatinwhichtheconcentrationofre breathingcarbondioxideismorethan1percent Insemi closedsystem somere breathingoccurs FGFandpop offsettingsshouldbeatintermediatevalues 4 Closedsystem Closedsystemissuchaconditionthatfreshgasinflowexactlyequaltopatientuptakeandthatcompletecarbondioxideisabsorbedaftercarbondioxideabsorbertakestheeffectsandpop offisclosed ComparisonofOpen semi open semi closed andclosedbreathingsystem 2 Non rebreathingandrebreathingsystems Theclassificationofnon rebreathingversusrebreathingsystemsismorewidelyused 1 Mapleson Non rebreathingbreathingsystem circuits OnekindofbreathingsystemwasintroducedbyProfessorW W Maplesonismostcommonlyusedintheworld Figure1 Maplesondescribedfivedifferentarrangementsofbreathingcircuits HeclassifedthesecircuitsandtheyarenowknownastheMaplesonsystems termedA E Thisclassificationdoesnotincludesystemswithcarbondioxide absorption TheoriginalMaplesonAsystem TheMaplesonA Magill systemwasdesignedbySirIvanMagillinthe1930 sandremainsanexcellentsystemforspontaneousventilation Figure2 Freshgasentersthesystematthefreshgasoutletoftheanesthesiamachine Thisisanefficientsystemforspontaneouslybreathingpatientsifcarbondioxideabsorptionisnotavailable DuringcontrolledventilationtheMagillcircuitworksinadifferentwayandbecomeswastefulandinefficient requiringhighfreshgasflowstopreventrebreathing Theexpiratoryvalve Heidbrinkvalve isveryclosetothepatienttoreducethedeadspace Therespiratorycyclehasthreephasesduringspontaneousbreathing inspiration expirationandtheexpiratorypause Duringinspirationgasisinhaledfromthe2litrereservoir breathing bagwhichpartiallycollapsesgivingavisualconfirmationthatbreathingisoccurring Duringexpirationthebagandtubingareinitiallyrefilledwithacombinationofexhaleddeadspacegas containingnocarbondioxide andfreshgasflowingfromtheanaestheticmachine Oncethebagisfull thepressurewithinthebreathingsystemrisesandtheexpiratoryvalvenearthepatientopensallowingthealveolargas containingcarbondioxide tobevented 排出 fromthesystem Duringtheexpiratorypause morefreshgasentersthesystemdrivinganyremainingalveolargasbackalongthecorrugated anesthetic tubingandoutthroughthevalve Ifthefreshgasflowissufficientlyhigh allthealveolargasisventedfromthecircuitbeforethenextinspirationandnorebreathingwilltakeplace Withcarefuladjustmentthefreshgasflowcanbereduceduntilthereisonlyfreshgasanddeadspacegasinthebreathingsystematthestartofinspiration Whenthesystemisfunctioningcorrectly withoutanyleaks afreshgasflow FGF equaltothepatient salveolarminuteventilationissufficienttopreventrebreathing Inpracticehowever aFGFclosertothepatientstotalminuteventilation includingdeadspace isusuallyselectedtoprovideamarginofsafety Anadult sminutevolumeisapproximately80mls kg minandthusfora75kgmanaFGFof6litresperminutewillpreventrebreathing Duringcontrolledventilation Theinspiratoryforceisprovidedbytheanesthesiologistwithsqueezingthereservoirbagafterpartlyorcompletelyclosingtheexpiratoryvalvenexttothepatient Duringlunginflationsomeofthegasisventedfromthecircuitandattheendofinspirationthereservoirbagislessthanhalffull Duringexpiration deadspaceandalveolargaspassdownthecorrugatedtubingandmayreachthebag whichwillthencontainsomecarbon dioxide Duringthenextinspirationwhenthebagiscompressedalveolargasre entersthepatientslungsfollowedbyamixtureoffresh deadspaceandalveolargas AFGFoftwoandahalftimesthepatient sminutevolumeisrequiredtoventenoughalveolargastominimiserebreathing FGFofabout12 15litres min whichisobviouslyveryinefficient InpracticetheMagillcircuitshouldnotbeusedforpositivepressureventilationexceptforshortperiodsofafewminutesatatime ModificationofMaplesonAsystem TheLackcircuitandtheBainsystemAdisadvantageoftheMagillsystemisthattheexpiratoryvalveisattachedclosetothepatientmakingitawkwardtouse particularlywhenascavengingcircuitisadded AsimplemodificationoftheMaplesonAbecameco axialsysteminwhichtheexhaledgasestraveldownacentraltubelocatedwithinanoutercorrugatedtubetowardstheexpiratoryvalve TheLackcircuit upperoneinFigure3 stillisaMaplesonAsystem However loweroneinFigure3 theBainsystem becameMaplesonDsystem Inthosemodifiedsystem theinnertubingiswideenoughtopreventanincreaseintheworkofbreathingandtheexpiratoryvalveisplacednexttothereservoirbag bythecommongasoutlet ThefreshgasflowsrequiredforbothspontaneousandcontrolledventilationareasdescribedforthestandardMaplesonAsystem 2 TheMaplesonBandC TheMaplesonBandCbreathingsystemsaresimilarinconstruction withthefreshgasflowentryandtheexpiratoryvalveslocatedatthepatientendofthecircuit Theyarenotcommonlyusedinanaestheticpractice althoughtheCsystemisusedonintensivecareunits HighflowsofgasesareneededtopreventrebreathingofCO2andCsystemwasatonetimecombinedwithacanisterofsodalimetoabsorbCO2 Waters ToandFro Circuit Howeverthecannisterprovedtoobulkyforpracticaluseandtherewasariskofthepatientinhalingsodalimedust Thereisdifferentlengthofthecorrugatedtubingbetweentheboth systems 3 TheMaplesonD EandFsystems TheMaplesonD EandFsystemsareallfunctionallysimilar TheMaplesonD E andFactasTpieceswiththeFGFdeliveredtothepatientendofthecircuitanddifferonlyinthepresenceofvalvesorbreathingbagsattheexpiratoryendofthecircuit A forspontaneousrespiration TheMaplesonD E andFactasTpieceswiththeFGFdeliveredtothepatientendofthecircuitanddifferonlyinthepresenceofvalvesorbreathingbagsattheexpiratoryendofthecircuit Thesesystemsareallinefficientforspontaneousrespiration Figure4 Figure4ModeofactionofMaplesonDbreathingsystemduringspontaneousventilation Thespontaneousrespiration inefficient Duringexpirationexhaledgasandfreshgasmixinthecorrugatedtubingandtraveltowardsthereservoirbag Whenthebagisfull thepressureinthesystemrisesandtheexpiratoryvalveopensventingamixtureoffreshandexhaledgastotheatmosphere Duringtheexpiratorypausefreshgascontinuestopushexhaledalveolargasdownthetubingtowardsthevalve However unlesstheFGFisatleasttwicethepatient sminutevolume rebreathingofalveolargaswilloccur AFGFofatleast8 10litres min 150mls kg min isrequiredtopreventrebreathingin anadult Thecontrolledventilation WhenusedforcontrolledventilationtheMaplesonDsystemfunctionsmoreefficiently Duringexpirationthecorrugatedtubingandreservoirbagfillwithamixtureoffreshandexhaledgas Freshgasfillsthedistalpartofthecorrugatedtubeduringtheexpiratorypausepriortoinspiration Whenthebagiscompressedthisfreshgasentersthelungsandwhentheexpiratoryvalveopensamixtureoffreshandexhaledgasisvented ThedegreeofrebreathingthatoccursdependsontheFGF AFGFof70ml kg minisusuallyadequateforcontrolledventilation 100mls kg minwillresultinadegreeofhypocapnia loweredCO2levelintheblood B Forthecontrolledventilation C ModificationsoftheMaplesonDsystem theBainCircuit TheBainCircuitisthemostcommonlyusedformoftheMaplesonDsystem Itisaco axialcircuitthatwasintroducedin1972byBainandSpoerel UnliketheLackco axialcircuitdescribedabove freshgasflowsdownthecentralnarrowboretubing 7mmi d tothepatientandexhaledgasestravelintheoutercorrugatedtubing 22mmi d ThedegreeofrebreathingthatoccursduringIPPVwilldependontheFGF Inanadult freshgasflowsof70 80mls kg min 6 7litres min willmaintainanormalarterialcarbondioxidetension normocapnia andaflowof100mls kg minwillresultinmildhypocapnia D TheMaplesonEsystem TheMaplesonEsystemperformsinasimilarwaytotheMaplesonD butbecausetherearenovalvesandthereisverylittleresistancetobreathingithasprovedverysuitableforusewithchildren Itwasoriginallyintroducedin1937byPAyreandisknown astheAyre sT piece E TheMaplesonFsystem TheversionmostcommonlyusedistheJackson Reesmodificationwhichhasanopenbagattachedtotheexpiratorylimb classifiedasaMaplesonFsystemalthoughitwasnotincludedintheoriginaldescriptionbyProfessorMapleson Movementofthebagcanbeseenduringspontaneousbreathing andthebagcanbecompressedtoprovidemanualventilation AsintheBaincircuit thebagmaybereplacedbyamechanicalventilatordesignedforusewithchildren Thissystemissuitableforchildrenunder20kg Freshgasflowsof2 3timesminutevolumeshouldbeusedtopreventrebreathingduringspontaneousventilation Duringcontrolledventilationinchildrennormocapniacanbemaintainedwithafreshgasflowof1000mls 100mls kg 2 rebreathingsystems CircleBreathingCircuit Thetermrebreathingimpliesthatexpiredalveolargascontaining5 carbondioxideisinspiredaspartofthenexttidalvolume Anaestheticcircuitsaredesignedtominimisethis asitmayleadtoseriouselevationsinbloodCO2levels AnalternativetousinghighflowcircuitsistoabsorbCO2fromtheexpiredgaseswhicharethenrecirculatedtothepatient Thesecircuitsareknownascirclesystems werefirstdevisedbyBrianSwordin1926andrequiresmalleramountsoffreshgaseachminute Theamountofrebreathingthatoccurswithanyparticularanaestheticbreathingsystemdependsonfourfactors thedesignoftheindividualbreathingcircuit themodeofventilation spontaneousorcontrolled thefreshgasflowrateandthepatient srespirator