动脉血气分析-ppt教学课件

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1、ArterialBloodGasAnalysisParamecium2007.3.29MIXEDVENOUSBLOODpH7.36PCO246mmHgPO240mmHgSO275%pH7.40PCO240mmHgPO295mmHgSO295%ARTERIALBLOODExternalRespirationInternalRespirationObtainingthebloodgasspecimenObtainingthebloodgasspecimenBloodcollectedanaerobically(radialart

2、ery)Thespecimenadequatelyanticoagulated(heparin)FreeofairbubblesandclotsA2mlsamplerecommendedThespecimenanalyzedinafewminutes,otherwisestoredinicewithin1hourEquipmentcalibrationandqualitycontrolThespecimenadequatelyidentified常压环境下，无论患者的吸氧条件如何，只要PaO2>48mmHg，则提示标本多为动脉

3、血自然状态下吸空气检查：PaO2+PaCO2<140mmHg若无原发代谢失衡证据，数小时内HCO3-浓度测量值变化<5mmol/LWhatInformationDoesArterialBloodGasprovide?AlveolarventilationArterialoxygenationRespiratory/metabolicacid-basebalanceAlveolarventilation肺泡通气(1)PaCO2是体现病人肺泡通气状态的唯一数值PaCO2升高即肺泡通气不足，PaCO2降低即肺泡通气过度PaCO2上升

4、的唯一生理原因是对于产生和运输到肺的CO2量，肺泡通气水平不足VCO2(ml/min)×0.863PaCO2＝VA(L/min)肺泡通气(2)VCO2:代谢产生并运输到肺的CO2量VA:肺泡分钟通气量＝分钟通气量(VE)－死腔通气量(VD)＝(潮气量－死腔量)×呼吸频率AnatomicdeadspaceAlveolardeadspacePaCO2与氧合及酸碱平衡的关系肺泡通气（5）VCO2(ml/min)×0.863PaCO2＝VA(L/min)PAO2=PIO2-1.2(PaCO2)pH=6.1+logHCO3-0.03Pa

5、CO2ArterialoxygenationHbPaO2和肺泡-动脉PO2差PaO2、SaO2和CaO2SaO2与SpO2ctHbctHb=cO2Hb+cHHb+cCOHb+cMetHbctHbisameasureofthetotalpotentialforoxygentransportinthebloodFO2HbItisameasureoftheutilizationofthepotentialoxygentransportcapacity.FCOHbTheaffinityofhemoglobinforcarbonmono

6、xideis200to250timesasgreatastheaffinityforoxygen.oxygentransportcapacity↓theleftshiftoftheODC.FMetHbFe2+→Fe3+.oxygen-carryingcapacity↓theaffinityforoxygen↑causedbydrugsorchemicalscontainingnitro-andaminogroups.Newbornscangetmethemoglobinemiaifgivennitrate-containing

7、wellwater.Excessivemethemoglobinemiamaybetreatedwithintravenousinfusionofmethyleneblueorbyred-celltransfusion.PaO2O2通过扩散进入肺毛细血管，所以PaO2决不可能超过PAO2PaO2=100-0.33×年龄Ⅰ型呼吸衰竭PaCO2正常或下降，PaO2<60mmHgⅡ型呼吸衰竭PaCO2>50mmHg，PaO2<60mmHg肺泡-动脉PO2差PAO2-PaO2指肺泡气和动脉血氧分压之间的差值。是判断氧弥散能力的一个重要

8、指标，FiO2、V/Q、Qs/Qt、膜弥散障碍、机体耗氧量（VO2）、心排量（CO）、氧合血红蛋白解离曲线均可影响。在所谓的理想肺中，PaO2=PAO2PAO2=PIO2-K×PaCO2=FIO2×(PB-47)-K×PaCO2=713×FIO2-K×PaCO2当FIO2<0