ICU必备课件1课件.ppt

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

2、.Cautionmustbetakenwithpatientonanticoagulants.Helpsdifferentiateoxygendeficienciesfromprimaryventilatorydeficienciesfromprimarymetabolicacid-baseabnormalitiesWhatIsAnABG?pH[H+]PCO2PartialpressureCO2PO2PartialpressureO2HCO3BicarbonateBEBaseexcessSaO2OxygenSatu

3、rationAcid/BaseRelationshipThisrelationshipiscriticalforhomeostasisSignificantdeviationsfromnormalpHrangesarepoorlytoleratedandmaybelifethreateningAchievedbyRespiratoryandRenalsystemsCaseStudyNo.160y/omalecomesERc/oSOB.Tachypneic,tachycardic,diaphoreticandCya

4、notic.Dxacuteresp.failureandABG’sShowPaCO2wellbelownl,pHabovenl,PaO2isverylow.ThebloodgasdocumentResp.failureduetoprimaryO2problem.CaseStudyNo.260y/omalecomesERc/oSOB.Tachypneic,tachycardic,diaphoreticandCyanotic.Dxacuteresp.failureandABG’sShowPaCO2veryhigh,lo

5、wpHandPaO2ismoderatelylow.ThebloodgasdocumentResp.failureduetoprimarilyventilatoryinsufficiency.TherearetwobuffersthatworkinpairsH2CO3NaHCO3CarbonicacidbasebicarbonateThesebuffersarelinkedtotherespiratoryandrenalcompensatorysystemBuffersRespiratoryComponentfu

6、nctionofthelungsCarbonicacidH2CO3Approximately98%normalmetabolitesareintheformofCO2CO2+H2OH2CO3excessCO2exhaledbythelungsMetabolicComponentFunctionofthekidneysbasebicarbonateNaHCO3ProcessofkidneysexcretingH+intotheurineandreabsorbingHCO3-intothebloodfromthe

7、renaltubules1)activeexchangeNa+forH+betweenthetubularcellsandglomerularfiltrate2)carbonicanhydraseisanenzymethataccelerateshydration/dehydrationCO2inrenalepithelialcellsH2O+CO2H2CO3HCO3+H+Acid/BaseRelationshipNormalABGvaluespH7.35–7.45PCO235–45mmHgPO280–

8、100mmHgHCO322–26mmol/LBE-2-+2SaO2>95%AcidosisAlkalosispH<7.35PCO2>45HCO3<22pH>7.45PCO2<35HCO3>26RespiratoryAcidosisThinkofCO2asanacidfailureofthelungstoexhaleadequateCO2pH<7.35PCO2