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1、ABGINTERPRETATION血气分析解读 SIMCICULiu Objectives What sanABG UnderstandingAcid BaseRelationshipGeneralapproachtoABGInterpretationClinicalcausesAbnormalABG sCasestudies WhatisanABG ArterialBloodGas动脉血气Drawnfromartery radial brachial femoral由动脉取样 一般取桡动脉 肱动脉 股动脉Itisaninvasiveprocedure 这是侵入性检查Cautionmustbe
2、takenwithpatientonanticoagulants 有凝血功能障碍的患者慎用Helpsdifferentiateoxygendeficienciesfromprimaryventilatorydeficienciesfromprimarymetabolicacid baseabnormalities协助区分缺氧 通气不足和酸碱代谢异常 WhatIsAnABG pH H PCO2PartialpressureCO2PO2PartialpressureO2HCO3BicarbonateBEBaseexcessSaO2OxygenSaturation Acid BaseRelation
3、ship Thisrelationshipiscriticalforhomeostasis酸碱平衡对内环境是非常重要的SignificantdeviationsfromnormalpHrangesarepoorlytoleratedandmaybelifethreatening酸碱严重失衡后果严重 甚至可能致命AchievedbyRespiratoryandRenalsystems一般由呼吸系统和肾脏决定 CaseStudyNo 1 60y omalecomesERc oSOB Tachypneic tachycardic diaphoreticandCyanotic Dxacuteresp
4、failureandABG sShowPaCO2wellbelownl pHabovenl PaO2isverylow ThebloodgasdocumentResp failureduetoprimaryO2problem 60岁男性进入急诊室 查体见呼吸过速 心动过速 大汗 发绀 诊断急性呼衰 动脉血气分析结果PaCO轻度降低 PH升高 PaO2非常低 结果显示其主要问题为缺氧 CaseStudyNo 2 60y omalecomesERc oSOB Tachypneic tachycardic diaphoreticandCyanotic Dxacuteresp failureandAB
5、G sShowPaCO2veryhigh lowpHandPaO2ismoderatelylow ThebloodgasdocumentResp failureduetoprimarilyventilatorinsufficiency 60岁男性进入急诊室 查体 呼吸过塑 心动过速 大汗 发绀 诊断急性呼衰 动脉血气分析结果显示PaCO2非常高 PH降低 PaO2中度降低 结果显示其主要问题为通气不足 Buffers TherearetwobuffersthatworkinpairsH2CO3NaHCO3CarbonicacidbasebicarbonateThesebuffersarelin
6、kedtotherespiratoryandrenalcompensatorysystem两者和呼吸 肾脏代偿密切相关 RespiratoryComponent functionofthelungsCarbonicacidH2CO3Approximately98 normalmetabolitesareintheformofCO2CO2 H2O H2CO3excessCO2exhaledbythelungs MetabolicComponent FunctionofthekidneysbasebicarbonateNaHCO3ProcessofkidneysexcretingH intothe
7、urineandreabsorbingHCO3 intothebloodfromtherenaltubules肾脏将H 排泄至尿液 并从肾小管重吸收HCO3 1 activeexchangeNa forH betweenthetubularcellsandglomerularfiltrate在肾小管和肾小球主动用Na 交换H 2 carbonicanhydraseisanenzymethataccelerateshydration dehydrationCO2inrenalepithelialcells可以加速CO2在肾上皮细胞的水化和脱水反应 Acid BaseRelationship H2
8、O CO2 H2CO3 HCO3 H NormalABGvalues pH7 35 7 45PCO235 45mmHgPO280 100mmHgHCO322 26mmol LBE 2 2SaO2 95 Acidosis酸中毒Alkalosis碱中毒 pH45HCO3 22 pH 7 45PCO226 RespiratoryAcidosis ThinkofCO2asanacid把二氧化碳想象成酸failureofthelungstoexhaleadequateCO2肺无法排出足够的二氧化碳pH45CO2 H2CO3 pH CausesofRespiratoryAcidosis Emphysema
9、肺气肿drugoverdose药物过量narcosis麻醉respiratoryarrest呼吸暂停airwayobstruction气道阻塞 MetabolicAcidosis failureofkidneyfunction bloodHCO3whichresultsin availabilityofrenaltubularHCO3forH excretionpH 7 35HCO3 22 CausesofMetabolicAcidosis renalfailure肾衰竭diabeticketoacidosis酮症酸中毒lacticacidosis乳酸酸中毒excessivediarrhea严
10、重腹泻cardiacarrest心跳骤停 RespiratoryAlkalosis toomuchCO2exhaled hyperventilation 过度通气 PCO2 H2CO3insufficiency pHpH 7 45PCO2 35 CausesofRespiratoryAlkalosis hyperventilation过度通气panicd opainpregnancyacuteanemia急性贫血salicylateoverdose水杨酸过量 MetabolicAlkalosis plasmabicarbonatepH 7 45HCO3 26 CausesofMetabolic
11、Alkalosis lossacidfromstomachorkidney由胃或肾脏过量丢失酸性物质hypokalemia低血钾excessivealkaliintake过量碱性物质摄入 HowtoAnalyzeanABG PO2NL 80 100mmHgpHNL 7 35 7 45Acidotic7 45PCO2NL 35 45mmHgAcidotic 45Alkalotic26 Four stepABGInterpretation Step1 ExaminePaO2 SaO2DetermineoxygenstatusLowPaO2 80mmHg SaO2meanshypoxiaPaO2和S
12、aO2降低提示缺氧NL elevatedoxygenmeansadequateoxygenation正常或更高的数值表明氧合充分 Four stepABGInterpretation Step2 pHacidosis7 45 Four stepABGInterpretation Step3 studyPaCO2 HCO3respiratoryirregularityifPaCO2abnl HCO3NL呼吸系统异常会显示PaCO2异常 HCO3正常metabolicirregularityifHCO3abnl PaCO2NL代谢系统异常会显示HCO3异常 PaCO2正常 Four stepABG
13、Interpretation Step4 DetermineifthereisacompensatorymechanismworkingtotrytocorrectthepH 判断机体是否在进行代偿ie ifhaveprimaryrespiratoryacidosiswillhaveincreasedPaCO2anddecreasedpH CompensationoccurswhenthekidneysretainHCO3 例如 如果主要是呼吸性酸中毒的话会导致PaCO2升高 PH降低 当肾脏仍有足够的HCO3时会进行代偿 PaCO2 pHRelationship 807 20607 3040
14、7 40307 50207 60 ABGInterpretation 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 A
15、cidosis酸中毒 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 R
16、espiratoryAcidosis pH7 30PaCO260HCO326 RespiratoryAlkalosis pH7 50PaCO230HCO322 MetabolicAcidosis pH7 30PaCO240HCO315 MetabolicAlkalosis pH7 50PCO240HCO330 Whatarethecompensations Respiratoryacidosis metabolicalkalosisRespiratoryalkalosis metabolicacidosisInrespiratoryconditions therefore thekidneyswillattempttocompensateandvisaversa Inchronicrespiratoryacidosis COPD thekidneysincreasetheeliminationofH andabsorbmoreHCO3 TheABGwillShowNLpH CO2andHCO3 Bufferskickinwithinminutes Respiratorycompensa
