文档介绍：HEPARININDUCEDTHROMBOCYTOPENIA:,MDProfessorofAnesthesiologyDeputyChair,ResearchEmoryUniversitySchoolofMedicineCardiothoracicAnesthesiologyandCriticalCareEmoryHealthcareAtlanta,PONENTSOFHEMOSTASISVasculatureCoagulationproteinsPlateletsAdhesionGpIIb/IIIaStimulationofPlateletsGpIIb/IIIaGpIIb/hrombinPlateletGpIbExposedCollagenEndotheliumvWFPAR-1(Thrombinreceptor)PAR-4GpIIb/IIIaGpIIb/IIIaAggregationGpIIb/IIIaGpIIb/IIIaAggregationAdhesionAggregationAdhesionADPAdrenalineAprotininHEPARINPolyanion:(-)chargeFromcowlung/pigintestineMixtureof3Kto30KMWtBindsATIII/inhibitsthrombinInhibitsXa,espLMWHReversiblewithprotamineCausesHITHeparin-inducedThrombocytopenia(HIT)Definition:HITisaseriousimmune-mediatedsyndromewhereheparinadministrationisassociatedwith:ThrombocytopeniaThegenerationofheparin-dependentantibodies(typicallyIgG)Ahighriskforthrombosiscausingsignificantmorbidityandmortality30%–50%;101:502–507Heparin-inducedThrombocytopeniaClinicalPresentation:Followingheparin:Thrombocytopeniaobserved5–14dayslater;ursoonerwithpreviousheparinexposurePlateletcount<100,000/µLorPlateletcount50%ofbaseline(pre-heparinvalue)HIT:PathophysiologyPresenceofIgGantibodiesthatrecognizePF4/plexesonplateletsurfaces andvascularwallsBindingofIgGtoPF4/plexes onplateletsAntibodyactivatesplateletsviatheFcreceptorActivatedplateletsreleasemicroparticles withprothromboticactivityPathophysiologyofHITandThrombosisLaboratoryTestingforHITTest Advantages DisadvantagesSRA Sensitivity>85% Technicallydemanding,radioisotopes; LowpredictivevalueHIPA Rapid,available Variablesensitivity(30%–80%); Technique-dependentELISA Highsensitivity Highcost,lowspecificity, 10%false-negativetestsThereisnoGoldStandardindiagnostictesting;HITrequiresaclinicaldiagnosis