ICU必备课件1课件.ppt

ABGINTERPRETATION DebbieSanderPAS II Objectives What sanABG UnderstandingAcid BaseRelationshipGeneralapproachtoABGInterpretationClinicalcausesAbnormalABG sCasestudiesTakehome WhatisanABG ArterialBloodGasDrawnfromartery radial brachial femoralItisaninvasiveprocedure Cautionmustbetakenwithpatientonanticoagulants Helpsdifferentiateoxygendeficienciesfromprimaryventilatorydeficienciesfromprimarymetabolicacid baseabnormalities WhatIsAnABG pH H PCO2PartialpressureCO2PO2PartialpressureO2HCO3BicarbonateBEBaseexcessSaO2OxygenSaturation Acid BaseRelationship ThisrelationshipiscriticalforhomeostasisSignificantdeviationsfromnormalpHrangesarepoorlytoleratedandmaybelifethreateningAchievedbyRespiratoryandRenalsystems CaseStudyNo 1 60y omalecomesERc oSOB Tachypneic tachycardic diaphoreticandCyanotic Dxacuteresp failureandABG sShowPaCO2wellbelownl pHabovenl PaO2isverylow ThebloodgasdocumentResp failureduetoprimaryO2problem CaseStudyNo 2 60y omalecomesERc oSOB Tachypneic tachycardic diaphoreticandCyanotic Dxacuteresp failureandABG sShowPaCO2veryhigh lowpHandPaO2ismoderatelylow ThebloodgasdocumentResp failureduetoprimarilyventilatoryinsufficiency TherearetwobuffersthatworkinpairsH2CO3NaHCO3CarbonicacidbasebicarbonateThesebuffersarelinkedtotherespiratoryandrenalcompensatorysystem Buffers RespiratoryComponent functionofthelungsCarbonicacidH2CO3Approximately98 normalmetabolitesareintheformofCO2CO2 H2O H2CO3excessCO2exhaledbythelungs MetabolicComponent FunctionofthekidneysbasebicarbonateNaHCO3ProcessofkidneysexcretingH intotheurineandreabsorbingHCO3 intothebloodfromtherenaltubules1 activeexchangeNa forH betweenthetubularcellsandglomerularfiltrate2 carbonicanhydraseisanenzymethataccelerateshydration dehydrationCO2inrenalepithelialcells H2O CO2 H2CO3 HCO3 H Acid BaseRelationship NormalABGvalues pH7 35 7 45PCO235 45mmHgPO280 100mmHgHCO322 26mmol LBE 2 2SaO2 95 AcidosisAlkalosis pH45HCO3 22 pH 7 45PCO226 RespiratoryAcidosis ThinkofCO2asanacidfailureofthelungstoexhaleadequateCO2pH45CO2 H2CO3 pH CausesofRespiratoryAcidosis emphysemadrugoverdosenarcosisrespiratoryarrestairwayobstruction MetabolicAcidosis failureofkidneyfunction bloodHCO3whichresultsin availabilityofrenaltubularHCO3forH excretionpH 7 35HCO3 22 CausesofMetabolicAcidosis renalfailurediabeticketoacidosislacticacidosisexcessivediarrheacardiacarrest RespiratoryAlkalosis toomuchCO2exhaled hyperventilation PCO2 H2CO3insufficiency pHpH 7 45PCO2 35 CausesofRespiratoryAlkalosis hyperventilationpanicd opainpregnancyacuteanemiasalicylateoverdose MetabolicAlkalosis plasmabicarbonatepH 7 45HCO3 26 CausesofMetabolicAlkalosis lossacidfromstomachorkidneyhypokalemiaexcessivealkaliintake HowtoAnalyzeanABG PO2NL 80 100mmHg2 pHNL 7 35 7 45Acidotic7 45PCO2NL 35 45mmHgAcidotic 45Alkalotic26 Four stepABGInterpretation Step1 ExaminePaO2 SaO2DetermineoxygenstatusLowPaO2 80mmHg SaO2meanshypoxiaNL elevatedoxygenmeansadequateoxygenation Step2 pHacidosis7 45 Four stepABGInterpretation Step3 studyPaCO2 HCO3respiratoryirregularityifPaCO2abnl HCO3NLmetabolicirregularityifHCO3abnl PaCO2NL Four stepABGInterpretation Step4 DetermineifthereisacompensatorymechanismworkingtotrytocorrectthepH ie ifhaveprimaryrespiratoryacidosiswillhaveincreasedPaCO2anddecreasedpH CompensationoccurswhenthekidneysretainHCO3 Four stepABGInterpretation PaCO2 pHRelationship 807 20607 30407 40307 50207 60 Compensated Respiratory Acidosis CO2 MoreAbnormal Respiratory Acidosis CO2 Expected Mixed Respiratory Metabolic Acidosis CO2 LessAbnormal CO2Change c w Abnormality Metabolic MetabolicAcidosis CO2 Normal Compensated Metabolic Acidosis CO2Change opposes Abnormality Acidosis ABGInterpretation Compensated Respiratory Alkalosis CO2 MoreAbnormal Respiratory Alkalosis CO2 Expected Mixed Respiratory Metabolic Alkalosis CO2 LessAbnormal CO2Change c w Abnormality Metabolic Alkalosis CO2 Normal Compensated Metabolic Alkalosis CO2Change opposes Abnormality Alkalosis ABGInterpretation RespiratoryAcidosis pH7 30PaCO260HCO326 RespiratoryAlkalosis pH7 50PaCO230HCO322 MetabolicAcidosis pH7 30PaCO240HCO315 MetabolicAlkalosis pH7 50PCO240HCO330 Whatarethecompensations Respiratoryacidosis metabolicalkalosisRespiratoryalkalosis metabolicacidosisInrespiratoryconditions therefore thekidneyswillattempttocompensateandvisaversa Inchronicrespiratoryacidosis COPD thekidneysincreasetheeliminationofH andabsorbmoreHCO3 TheABGwillShowNLpH CO2and HCO3 Bufferskickinwithinminutes Respiratorycompensationisrapidandstartswithinminutesandcompletewithin24hours Kidneycompensationtakeshoursandupto5days MixedAcid BaseAbnormalities CaseStudyNo 3 56yo neurologicdzrequiredventilatorsupportforseveralweeks SheseemedmostcomfortablewhenhyperventilatedtoPaCO228 30mmHg Sherequireddailydosesoflasixtoassureadequateurineoutputandreceived40mmol LIVK eachday On10thdayofICUherABGon24 oxygen VS ABGResults pH7 62BP115 80mmHgPCO230mmHgPulse88 minPO285mmHgRR10 minHCO330mmol LVT1000mlBE10mmol LMV10LK 2 5mmol L Interpretation Acutealveolarhyperventilation resp alkalosis andmetabolicalkalosiswithcorrectedhypoxemia CasestudyNo 4 27yoretarded withinsulin dependentDMarrivedatERfromtheinstitutionwherehelived OnroomairABG VS pH7 15BP180 110mmHgPCO222mmHgPulse130 minPO292mmHgRR40 minHCO39mmol LVT800mlBE 30mmol LMV32L Interpretation Partlycompensatedmetabolicacidosis CasestudyNo 5 74yo withhxchronicrenalfailureandchronicdiuretictherapywasadmittedtoICUcomatoseandseverelydehydrated On40 oxygenherABG VS pH7 52BP130 90mmHgPCO255mmHgPulse120 minPO292mmHgRR25 minHCO342mmol LVT150mlBE17mmol LMV3 75L Interpretation Partlycompensatedmetabolicalkalosiswithcorrectedhypoxemia CasestudyNo 6 43yo arrivesinER20minutesafteraMVAinwhichheinjuredhisfaceonthedashboard Heisagitated hasmottled coldandclammyskinandhasobviouspartialairwayobstruction Anoxygenmaskat10Lisplacedonhisface ABG VS pH7 10BP150 110mmHgPCO260mmHgPulse150 minPO2125mmHgRR45 minHCO318mmol LVT mlBE 15mmol LMV L Interpretation Acuteventilatoryfailure resp acidosis andacutemetabolicacidosiswithcorrectedhypoxemia CasestudyNo 7 17yo 48kg withknowninsulin dependentDMcametoERwithKussmaulbreathingandirregularpulse RoomairABG VS pH7 05BP140 90mmHgPCO212mmHgPulse118 minPO2108mmHgRR40 minHCO35mmol LVT1200mlBE 30mmol LMV48L Interpretation Severepartlycompensatedmetabolicacidosiswithouthypoxemia CaseNo 7cont d Thispatientisindiabeticketoacidosis IVglucoseandinsulinwereimmediatelyadministered AjudgementwasmadethatsevereacidemiawasadverselyaffectingCVfunctionandbicarbwaselectedtorestorepHto 7 20 Bicarbadministrationcalculation BasedeficitXweight kg 430X48 360mmol LAdmin1 2over15min 4repeatABG CaseNo 7cont d ABGresultafterbicarb pH7 27BP130 80mmHgPCO225mmHgPulse100 minPO292mmHgRR22 minHCO311mmol LVT600mlBE 14mmol LMV13 2L CasestudyNo 8 47yo wasinPACUfor3hourss pcholecystectomy Shehadbeenon40 oxygenandABG VS pH7 44BP130 90mmHgPCO232mmHgPulse95 min regularPO2121mmHgRR20 minHCO322mmol LVT350mlBE 2mmol LMV7LSaO298 Hb13g dL CaseNo 8cont d Oxygenwaschangedto2LN C 1 2hourpt readytobeD CtofloorandABG VS pH7 41BP130 90mmHgPCO210mmHgPulse95 min regularPO2148mmHgRR20 minHCO36mmol LVT350mlBE 17mmol LMV7LSaO299 Hb7g dL CaseNo 8cont d Whatisgoingon CaseNo 8cont d Ifthepicturedoesn tfit repeatABG pH7 45BP130 90mmHgPCO231mmHgPulse95 minPO287mmHgRR20 minHCO322mmol LVT350mlBE 2mmol LMV7LSaO296 Hb13g dL Technicalerrorwaspresumed CasestudyNo 9 67yo whohadclosedreductionoflegfxwithoutincident FourdayslatersheexperiencedasuddenonsetofseverechestpainandSOB RoomairABG VS pH7 36BP130 90mmHgPCO233mmHgPulse100 minPO255mmHgRR25 minHCO318mmol LBE 5mmol LMV18LSaO288 Interpretation Compensatedmetabolicacidosiswithmoderatehypoxemia Dx PE CasestudyNo 10 76yo withdocumentedchronichypercapniasecondarytosevereCOPDhasbeeninICUfor3dayswhilebeingtxforpneumonia Shehadbeenstableforpast24hoursandwastransferredtogeneralfloor Ptwason2Loxygen ABG VS pH7 44BP135 95mmHgPCO263mmHgPulse110 minPO252mmHgRR22 minHCO342mmol LBE 16mmol LMV10LSaO286 Interpretation Chronicventilatoryfailure resp acidosis withuncorrectedhypoxemia CaseNo 10cont d Shewasplacedon3Landmonitoredfornexthour Sheremainedalert orientedandcomfortable ABGwasrepeated pH7 36BP140 100mmHgPCO275mmHgPulse105 minPO265mmHgRR24 minHCO342mmol LBE 16mmol LMV4 8LSaO292 Pt sventilatorypatternhaschangedtomorerapidandshallowbreathing AlthoughstillacceptablethepHandCO2aretrendinginthewrongdirection High flowoxygenmaybebetterforthispttopreventintubation TakeHomeMessage ValuableinformationcanbegainedfromanABGastothepatientsphysiologicconditionRememberthatABGanalysisifonlypartofthepatientassessment Besystematicwithyouranalysis startwithABC sasalwaysandlookforhypoxia whichyoucanusuallytreatquickly thenfollowthe