病理生理5缺氧

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1、缺氧(hypoxia)【Hypoxia】当组织的氧供应不足，或组织利用氧障碍时，导致机体功能、代谢和形态结构的异常变化，甚至危及生命的病理状态。一、概念（Concept）Hypoxiaisreferredtoapathologicalprocessinwhichoxygensupplytotissuesororgansisinadequatetomeetthedemandofcells,orthereisadequatedeliverytotissuebutthetissuecellscannotmakeuseofoxygen,leadingtochangesinfunctio

2、ns,metabolismsandstructuresofcellsandtissuesofthebody.Hypoxia【Hypoxemia】指动脉血氧含量明显降低引起对组织供氧不足。Oxygencontentofthearterialbloodislowerthannormalthatiscalledhypoxemia.Hypoxia二、血氧检测指标（Parametersofbloodoxygen）Hypoxia氧分压（Partialpressureofoxygen,PO2）1Hypoxia血氧容量（Oxygenbindingcapacity,CO2max）2氧含量（Oxy

3、gencontent,CO2）3动-静脉氧差（A-VdO2）4氧饱和度（Oxygensaturation,SO2）5P506■Partialpressureofoxygen,(PO2)【Definiens】PO2isthepressureortensioncausedbyoxygenphysicallyDissolvedintheblood.Hypoxia【Significance】PaO2高低直接影响动脉血氧含量（O2与Hb结合）、血氧饱和度、氧弥散速度。【Normalvalue】PaO2:13.3kPa(100mmHg)；PvO2:5.32kPa(40mmHg)。【Infl

4、uence】吸入空气的pO2、肺的呼吸功能、静脉血掺杂程度。19ml/dl14ml/dl5ml/dlO2AVO2O2O2O2O2■A-VdO2【Definiens】Thedifferencevalueisbetweenarterialandvenousbloodoxygencontent.【Significance】反映100ml血液流经组织时所提供的氧量或组织细胞利用氧量。【Normalvalue】A-VdO2通常为2.23～3.57mmol/L(5ml%～8ml%)。Hypoxia■Oxygensaturation,SO2【Definiens】Thedegreeofconn

5、ected1gHbtooxygenSO2%=CO2–O2dissolvedphysicallyinplasma/CO2max【Normalvalue】SaO2：93%～98%；SvO2：70%～75%。【Significance】反映Hb与氧的结合程度。【Influence】PaO2。FactorsaffectingoxygendissociationcurveHypoxiaP50■P50【Definiens】OnemeasureofthepositionofthecurveisthePO2atthe50%SO2.【Significance】TheP50indicatesaff

6、inityofhemoglobinforoxygen.【Normalvalue】3.47～3.6kPa(26～27mmHg)。【Influence】H+、CO2、温度、2、3-DPGHypoxia呼吸与氧利用AirAlveoliAlveolarcapillaryGastransportTissuecellsVentilationGasexchangeExternalrespirationInternalrespirationBoundtohaemoglobinClassificationofhypoxiaHypotonicHypoxia(HypoxicHypoxia)Class

7、ificationandEtiologyClassificationofhypoxiaHemicHypoxia(IsotonicHypoxia)CirculatoryHypoxia(HypokineticHypoxia)HistogenousHypoxia(HistotoxicHypoxia)Classificationofhypoxia（一）低张性缺氧（HypotonicHypoxia）1．特征（Feature）以动脉血氧分压（PaO2）明显降低并导致对组织供氧不足为主要特点的缺氧症。Th