病理生理学-呼吸系统

病理生理学系DepartmentofPathophysiology高远生,呼吸衰竭RespiratoryFailure,Symbols,呼吸衰竭(RespiratoryFailure),呼吸功能不全(RespiratoryInsufficiency),呼衰的类型ClassificationofRespiratoryfailure,1.按PaCO2是否升高：低氧血症型（I型）低氧血症伴高碳酸血症（II型）2.按主要发病机制：通气障碍型换气障碍型3.按病变部位：中枢性和外周性,一、呼衰的原因和发病机制RespiratoryFailure:TheCausesandtheMechanisms,.肺通气功能障碍DisordersinPulmonaryVentilation.肺换气功能障碍DisordersinGasExchangeoftheLungs,（一）肺通气功能障碍:DisordersinPulmonaryVentilation,气道阻力(正常人平静呼吸)：80%:直径2mm气管20%:直径0.80.8,1.部分肺泡通气不足(AlveolarVentilationInsufficiency)功能性分流(functionalshunt)静脉血掺杂（venousadmixture),血液氧和二氧化碳解离曲线OxygenandCarbonDioxideDissociationCurves,氧和二氧化碳血液中的运输TransportofO2andCO2intheBlood,2.解剖分流增加(IncreaseinAnatomicShunt),3.部分肺泡血流不足(AlveolarPerfusionInsufficiency)死腔样通气(deadspacelikeventilation）,血液氧和二氧化碳解离曲线OxygenandCarbonDioxideDissociationCurves,问题：弥散障碍的发生机制?功能性分流,静脉血掺杂?解剖分流,真性分流?死腔样通气?,肺泡-毛细血管膜(alveolarcapillarymembrane)损伤引起的急性呼吸衰竭。病因：感染（肺炎，败血症等），休克，严重创伤，吸入毒物或胃酸等。,（四）急性呼吸窘迫综合征AcuteRespiratoryDistressSyndrome(ARDS),Severeacuterespiratorysyndrome(SARS)isagoodexampleofaprobableinfectiouspneumoniathatpathologicallyandclinicallyisARDS.Expertshavespeculatedthatthecauseisfromacoronavirusthatmaybetransmittedviarespiratorysecretionsanddevelopsafter2-11daysofafebrileillness.,Apreviouslyhealthy23-year-oldmalesustainednumeroustraumaticcrush,burn,andsmokeinhalationinjuriesduringalandingaccidentinanairplane.HisinitialB.P.was80/50mmHg,andhewasimmediatelyinfusedwithsalineatthemaximalrate.IntheERhewasintubatedandhadnosignsofpneumothorax.Hisorthopedicinjuriesandburnsweretreated.Theventilatorwasplacedontheassist-controlmodewiththeinitialsettingsofinspiredO2concentrationat40%,respirationrateat12/min,andtidalvolumeat900ml.Arterialbloodgasmeasurementswere:pH=7.47,PCO2of33mmHg,andPO2of62mmHg.,ClinicalCase,24hrs.afteradmission,thepatientbecomesagitatedandhisrespirationrateincreasedto30/min.Hisminuteventilationalsoincreasedfrom8.5l/minto20l/min.Airwaypressureincreasedfrom18to65cmH2O.RepeatarterialbloodgasmeasurementofPO2indicated35mmHgandchestx-raynowshoweddiffuseinfiltratesinawhiteoutpattern.,ClinicalCase,ThediagnosisofARDSiscontingentupon5factors:1.Hypoxemia,2.Diffusepulmonaryinfiltratesonradiography,3.Absenceofcongestiveheartfailure,4.Decreasedlungcompliance(effectivestaticcompliance80mmHgCO2麻醉(头痛,头昏,嗜睡，精神错乱,扑翼样震颤,抽搐,及昏迷等中枢神经系统症状）肺性脑病(pulmonaryencephalopathy):呼衰引起的脑功能障碍,（四）中枢神经系统变化ChangesinCentralNervousSystem,肺性脑病发生机制Pathogenesisofpulmonaryencephalopathy,问题：呼吸衰竭时呼吸调节的变化？肺源性心脏病发生机制?肺性脑病的定义及发生机制？,（一）一般原则(GeneralPrincipals)1.防治原发病2.防止或去除诱因3.改善肺通气4.纠正水、电解质及酸碱平衡紊乱,保护重要器官功能,五、呼衰的防治原则PrincipalsofthePreventionandTreatmentofRespiratoryFailure,1I型呼衰只有缺O2而无CO2潴留，可吸入较高浓度O2，一般不超过502.II型呼衰有CO2潴留,应持续低浓度低流量吸氧，如30，12L/min，使PaO2上升到60mmHg,（二）吸氧(OxygenInhalation),问题：II型呼吸衰竭吸氧的原则？,respiratoryfailure(respiratoryinsufficiency()restrictivehypoventilation()obstructivehypoventilation()diffusionimpairment()functionalshunt()venousadmixture()anatomicshunt();trueshunt()deadspacelikeventilation()ventilation-perfusionratio()acuterespiratorydistresssyndrome(ARDS)()corpulmonale()pulmonaryencephalopathy(),respiratoryfailure(呼吸衰竭)respiratoryinsufficiency(呼吸功能不全)restrictivehypoventilation(限制性通气不足)obstructivehypoventilation(阻塞性通气不足)diffusionimpairment(弥散障碍)functionalshunt(功能性分流)venousadmixture(静脉血掺杂)anatomicshunt(解剖分流);trueshunt(真性分流)deads