ICU必备课件1课件PPT推荐.ppt

ICU必备课件1课件PPT推荐.ppt

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ABGINTERPRETATIONDebbieSanderPAS-IIObjectivesWhatsanABG?

@#@UnderstandingAcid/BaseRelationshipGeneralapproachtoABGInterpretationClinicalcausesAbnormalABGsCasestudiesTakehomeWhatisanABGArterialBloodGasDrawnfromartery-radial,brachial,femoralItisaninvasiveprocedure.Cautionmustbetakenwithpatientonanticoagulants.Helpsdifferentiateoxygendeficienciesfromprimaryventilatorydeficienciesfromprimarymetabolicacid-baseabnormalitiesWhatIsAnABG?

@#@pHH+PCO2PartialpressureCO2PO2PartialpressureO2HCO3BicarbonateBEBaseexcessSaO2OxygenSaturationAcid/BaseRelationshipThisrelationshipiscriticalforhomeostasisSignificantdeviationsfromnormalpHrangesarepoorlytoleratedandmaybelifethreateningAchievedbyRespiratoryandRenalsystemsCaseStudyNo.160y/omalecomesERc/oSOB.Tachypneic,tachycardic,diaphoreticandCyanotic.Dxacuteresp.failureandABGsShowPaCO2wellbelownl,pHabovenl,PaO2isverylow.ThebloodgasdocumentResp.failureduetoprimaryO2problem.CaseStudyNo.260y/omalecomesERc/oSOB.Tachypneic,tachycardic,diaphoreticandCyanotic.Dxacuteresp.failureandABGsShowPaCO2veryhigh,lowpHandPaO2ismoderatelylow.ThebloodgasdocumentResp.failureduetoprimarilyventilatoryinsufficiency.TherearetwobuffersthatworkinpairsH2CO3NaHCO3CarbonicacidbasebicarbonateThesebuffersarelinkedtotherespiratoryandrenalcompensatorysystemBuffersRespiratoryComponentfunctionofthelungsCarbonicacidH2CO3Approximately98%normalmetabolitesareintheformofCO2CO2+H2OH2CO3excessCO2exhaledbythelungsMetabolicComponentFunctionofthekidneysbasebicarbonateNaHCO3ProcessofkidneysexcretingH+intotheurineandreabsorbingHCO3-intothebloodfromtherenaltubules1）activeexchangeNa+forH+betweenthetubularcellsandglomerularfiltrate2）carbonicanhydraseisanenzymethataccelerateshydration/dehydrationCO2inrenalepithelialcellsH2O+CO2H2CO3HCO3+H+Acid/BaseRelationshipNormalABGvaluespH7.357.45PCO23545mmHgPO280100mmHgHCO32226mmol/LBE-2-+2SaO295%AcidosisAlkalosispH45HCO37.45PCO226RespiratoryAcidosisThinkofCO2asanacidfailureofthelungstoexhaleadequateCO2pH45CO2+H2CO3pHCausesofRespiratoryAcidosisemphysemadrugoverdosenarcosisrespiratoryarrestairwayobstructionMetabolicAcidosisfailureofkidneyfunctionbloodHCO3whichresultsinavailabilityofrenaltubularHCO3forH+excretionpH7.35HCO37.45PCO27.45HCO326CausesofMetabolicAlkalosislossacidfromstomachorkidneyhypokalemiaexcessivealkaliintakeHowtoAnalyzeanABG1.PO2NL=80100mmHg2.pHNL=7.357.45Acidotic7.453.PCO2NL=3545mmHgAcidotic45Alkalotic354.HCO3NL=2226mmol/LAcidotic26Four-stepABGInterpretationStep1:

@#@ExaminePaO2&@#@SaO2DetermineoxygenstatusLowPaO2（80mmHg）&@#@SaO2meanshypoxiaNL/elevatedoxygenmeansadequateoxygenationStep2:

@#@pHacidosis7.45Four-stepABGInterpretationStep3:

@#@studyPaCO2&@#@HCO3respiratoryirregularityifPaCO2abnl&@#@HCO3NLmetabolicirregularityifHCO3abnl&@#@PaCO2NLFour-stepABGInterpretationStep4:

@#@DetermineifthereisacompensatorymechanismworkingtotrytocorrectthepH.ie:

@#@ifhaveprimaryrespiratoryacidosiswillhaveincreasedPaCO2anddecreasedpH.CompensationoccurswhenthekidneysretainHCO3.Four-stepABGInterpretationPaCO2pHRelationship807.20607.30407.40307.50207.60CompensatedRespiratoryAcidosisCO2MoreAbnormalRespiratoryAcidosisCO2ExpectedMixedRespiratoryMetabolicAcidosisCO2LessAbnormalCO2Changec/wAbnormalityMetabolicMetabolicAcidosisCO2NormalCompensatedMetabolicAcidosisCO2ChangeopposesAbnormalityAcidosisABGInterpretationCompensatedRespiratoryAlkalosisCO2MoreAbnormalRespiratoryAlkalosisCO2ExpectedMixedRespiratoryMetabolicAlkalosisCO2LessAbnormalCO2Changec/wAbnormalityMetabolicAlkalosisCO2NormalCompensatedMetabolicAlkalosisCO2ChangeopposesAbnormalityAlkalosisABGInterpretationRespiratoryAcidosispH7.30PaCO260HCO326RespiratoryAlkalosispH7.50PaCO230HCO322MetabolicAcidosispH7.30PaCO240HCO315MetabolicAlkalosispH7.50PCO240HCO330Whatarethecompensations?

@#@RespiratoryacidosismetabolicalkalosisRespiratoryalkalosismetabolicacidosisInrespiratoryconditions,therefore,thekidneyswillattempttocompensateandvisaversa.Inchronicrespiratoryacidosis（COPD）thekidneysincreasetheeliminationofH+andabsorbmoreHCO3.TheABGwillShowNLpH,CO2andHCO3.Bufferskickinwithinminutes.Respiratorycompensationisrapidandstartswithinminutesandcompletewithin24hours.Kidneycompensationtakeshoursandupto5days.MixedAcid-BaseAbnormalitiesCaseStudyNo.3:

@#@56yoneurologicdzrequiredventilatorsupportforseveralweeks.SheseemedmostcomfortablewhenhyperventilatedtoPaCO228-30mmHg.Sherequireddailydosesoflasixtoassureadequateurineoutputandreceived40mmol/LIVK+eachday.On10thdayofICUherABGon24%oxygen&@#@VS:

@#@ABGResultspH7.62BP115/80mmHgPCO230mmHgPulse88/minPO285mmHgRR10/minHCO330mmol/LVT10