任职资格预审表“主要业务ppt课件.ppt

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1、HEPARININDUCEDTHROMBOCYTOPENIA:HITHAPPENSJerroldH.Levy,MDProfessorofAnesthesiologyDeputyChair,ResearchEmoryUniversitySchoolofMedicineCardiothoracicAnesthesiologyandCriticalCareEmoryHealthcareAtlanta,GeorgiaHemostasisSubendothelialmatrixPlateletsHemostaticplugFibrinEndothelialcellRB

2、CWBCCOMPONENTSOFHEMOSTASISVasculatureCoagulationproteinsPlateletsAdhesionGpIIb/IIIaStimulationofPlateletsGpIIb/IIIaGpIIb/IIIaAggregationADPAdrenalineThrombinPlateletGpIbExposedCollagenEndotheliumvWFPAR-1(Thrombinreceptor)PAR-4GpIIb/IIIaGpIIb/IIIaAggregationGpIIb/IIIaGpIIb/IIIaAggre

3、gationAdhesionAggregationAdhesionADPAdrenalineAprotininHEPARINPolyanion:(-)chargeFromcowlung/pigintestineMixtureof3Kto30KMWtBindsATIII/inhibitsthrombinInhibitsXa,espLMWHReversiblewithprotamineCausesHITHeparin-inducedThrombocytopenia(HIT)Definition:HITisaseriousimmune-mediatedsyndro

4、mewhereheparinadministrationisassociatedwith:ThrombocytopeniaThegenerationofheparin-dependentantibodies(typicallyIgG)Ahighriskforthrombosiscausingsignificantmorbidityandmortality30%–50%ofpatientswithHITwillhaveathromboticcomplicationwithin30daysWarkentinTEAmJMed.1996;101:502–507Hep

5、arin-inducedThrombocytopeniaClinicalPresentation:Followingheparin:Thrombocytopeniaobserved5–14dayslater;ormayoccursoonerwithpreviousheparinexposurePlateletcount<100,000/µLorPlateletcount50%ofbaseline(pre-heparinvalue)HIT:PathophysiologyPresenceofIgGantibodiesthatrecognizePF4/hepari

6、ncomplexesonplateletsurfacesandvascularwallsBindingofIgGtoPF4/heparincomplexesonplateletsAntibodyactivatesplateletsviatheFcreceptorActivatedplateletsreleasemicroparticleswithprothromboticactivityPathophysiologyofHITandThrombosisLaboratoryTestingforHITTestAdvantagesDisadvantagesS

7、RASensitivity>85%Technicallydemanding,radioisotopes;LowpredictivevalueHIPARapid,availableVariablesensitivity(30%–80%);Technique-dependentELISAHighsensitivityHighcost,lowspecificity,10%false-negativetestsThereisnoGoldStandardindiagnostictesting;HITrequiresaclinicaldiagnosisSequel

8、aeIncidenceThrombosis30%–5