《ICU必备》PPT课件

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1、ABGINTERPRETATIONDebbieSanderPAS-IIObjectivesWhat’sanABG?UnderstandingAcid/BaseRelationshipGeneralapproachtoABGInterpretationClinicalcausesAbnormalABG’sCasestudiesTakehomeWhatisanABGArterialBloodGasDrawnfromartery-radial,brachial,femoralItisaninvasiveprocedure.Cautionmustbetakenwithpat

2、ientonanticoagulants.Helpsdifferentiateoxygendeficienciesfromprimaryventilatorydeficienciesfromprimarymetabolicacid-baseabnormalitiesWhatIsAnABG?pH[H+]PCO2PartialpressureCO2PO2PartialpressureO2HCO3BicarbonateBEBaseexcessSaO2OxygenSaturationAcid/BaseRelationshipThisrelationshipiscritica

3、lforhomeostasisSignificantdeviationsfromnormalpHrangesarepoorlytoleratedandmaybelifethreateningAchievedbyRespiratoryandRenalsystemsCaseStudyNo.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、twobuffersthatworkinpairsH2CO3NaHCO3CarbonicacidbasebicarbonateThesebuffersarelinkedtotherespiratoryandrenalcompensatorysystemBuffersRespiratoryComponentfunctionofthelungsCarbonicacidH2CO3Approximately98%normalmetabolitesareintheformofCO2CO2+H2OH2CO3excessCO2exhaledbythelungsMetabol

6、icComponentFunctionofthekidneysbasebicarbonateNaHCO3ProcessofkidneysexcretingH+intotheurineandreabsorbingHCO3-intothebloodfromtherenaltubules1)activeexchangeNa+forH+betweenthetubularcellsandglomerularfiltrate2)carbonicanhydraseisanenzymethataccelerateshydration/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