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1、ABGINTERPRETATIONDebbieSanderPAS-IIObjectivesWhat’sanABG?UnderstandingAcid/BaseRelationshipGeneralapproachtoABGInterpretationClinicalcausesAbnormalABG’sCasestudiesTakehomeWhatisanABGArterialBloodGasDrawnfromartery-radial,brachial,femoralItisaninvasiveprocedure.Cautionmustbetakenwithpat
2、ientonanticoagulants.Helpsdifferentiateoxygendeficienciesfromprimaryventilatorydeficienciesfromprimarymetabolicacid-baseabnormalitiesWhatIsAnABG?pH[H+]PCO2PartialpressureCO2PO2PartialpressureO2HCO3BicarbonateBEBaseexcessSaO2OxygenSaturationAcid/BaseRelationshipThisrelationshipiscritica
3、lforhomeostasisSignificantdeviationsfromnormalpHrangesare poorlytoleratedandmaybelifethreateningAchievedbyRespiratoryandRenalsystemsCaseStudyNo.160y/omalecomesERc/oSOB.Tachypneic,tachycardic,diaphoreticandCyanotic.Dxacuteresp.failureandABG’sShowPaCO2wellbelownl,pHabovenl,PaO2isverylow.
4、ThebloodgasdocumentResp.failureduetoprimaryO2problem.CaseStudyNo.260y/omalecomesERc/oSOB.Tachypneic,tachycardic,diaphoreticandCyanotic.Dxacuteresp.failureandABG’sShowPaCO2veryhigh,lowpHandPaO2ismoderatelylow.ThebloodgasdocumentResp.failureduetoprimarilyventilatoryinsufficiency.Thereare
5、twobuffersthatworkinpairsH2CO3NaHCO3CarbonicacidbasebicarbonateThesebuffersarelinkedtotherespiratoryand renalcompensatorysystemBuffersRespiratoryComponentfunctionofthelungsCarbonicacidH2CO3Approximately98%normalmetabolitesareintheform ofCO2CO2+H2O?H2CO3excessCO2exhaledbythelungsMetabol
6、icComponentFunctionofthekidneysbasebicarbonateNaHCO3ProcessofkidneysexcretingH+intotheurineandreabsorbing HCO3-intothebloodfromtherenaltubules 1)activeexchangeNa+forH+betweenthetubular cellsandglomerularfiltrate 2)carbonicanhydraseisanenzymethataccelerates hydration/dehydrationCO2inren
7、alepithelialcellsH2O+CO2?H2CO3?HCO3+H+Acid/BaseRelationshipNormalABGvaluespH7.35–7.45PCO235–45mmHgPO280–100mmHgHCO322–26mmol/LBE-2-+2SaO2>95%AcidosisAlkalosispH<7.35PCO2>45HCO3<22pH>7.45PCO2<35HCO3>26RespiratoryAcidosisThinkofCO2asanacidfailureofthelungstoexhaleadequateCO2pH<7.35PCO2
