病理生理学呼吸系统.ppt

**Mortality:30-40%;survivors:respiratoryfunctionrecoverswithin6-12months.Background:Ashbaughandcolleaguesfirstdescribedacuterespiratorydistresssyndrome(ARDS)in1967.Theydescribedthesyndromeasacuteonsetofsevererespiratorydistress,cyanosis(hypoxemia)refractorytooxygentherapy,diffuseabnormalitiesonchestradiographs(CXRs),anddecreasedlungcompliance.In1994,theAmerican-EuropeanConsensusConference(AECC)onARDSformulatedtheirdefinitionofARDSasfollows:AcuteonsetofsymptomsRatioofPaO2tothefractionofinspiredoxygen(FIO2)of200mmHgorlessBilateralinfiltratesonCXRsPulmonaryarterialwedgepressureof18mmHgorlessornoclinicalsignsofleftatrialhypertensionTheradiographicabnormalitiesofARDSreflecttheleakageoffluidwithahighproteincontentintothealveolarspacesbecauseofalveolarepithelialinjury,ordiffusealveolardamage.ARDSisasyndromedefinedbyitsclinicalfeatures.Itmayresultfromintrathoracicorextrathoraciceventsofvariousetiologies,suchasinflammatory,infectious,vascular,ortraumaticetiologies.Determiningthecausativeeventmaybeclinicallyimportantforpropertreatment.ARDSisasyndromethatcommonlybeginsafterexposuretoaknownriskfactor.WhysomepeopledevelopARDSandothersdonotisstillunknown.TheriskfactorsforARDSincludeprimarypulmonaryetiologies(eg,aspiration,pneumonia,toxicinhalation,pulmonarycontusion)andextrapulmonaryetiologies(eg,sepsis,pancreatitis,multiplebloodtransfusions,trauma,useofdrugssuchasheroin).Sometimes,ARDSisnotonlyareactiontoanothereventbutalsotheresultofaknowncausesuchasacuteinterstitialpneumoniaorasevere,extensive,infectiouspneumonia.Pathophysiology:Thediagnosticcriterionstandardispathologicevidenceofdiffusealveolardamageobtainedfromlungtissueviabiopsy.However,biopsymaynotbepossiblebecauseofthepatient抯