凝血与血小板减少.ppt

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Treatment of DVT’s—Why?(ie. How not to clot) What are the goals of therapy? Prevent morbidity and mortality from pulmonary emboli Reduce morbidity from acute thrombus Minimize postphlebitic symptoms Prevent thromboembolic pulmonary hypertension How to treat a clot Anticoagulant therapy—heparin, warfarin Thrombolytic therapy Surgical thrombectomy Vena caval interruption What are the goals of therapy? InitialClot management Candidate for thrombolysis? yes unfractionated heparin CVDL consultation Long-term anticoagulation LMWH or coumadin no unfractionated heparin or low molecular weight heparin thrombolysis InitialClot management Start Heparinization for 5 to 7 days Standard Heparin IV: Load 75 units/kg 1 year—28 units/kg/hr 1 year—20 units/kg/hr Keep APTT 60 to 85 sec Or control ratio 1.5 to 2.5 X LMW Heparin sq: 2 months—1.5 mg/kg q12 hr 2 months—1.0 mg/kd q12 hr Monitor anti Xa level 4 to 6 hours after 1st or 2nd dose. Strief et al 2003, Arch Dis Child Fetal Neonatal Ed. Can you use LMWH in premies? Heparin-- physical characteristics Pentasacchride ATIII binding sequence Heparin—physical characteristicsIt binds to Antithrombin heparin pentasaccharide binding to antithrombin Activation loop binds to reactive Site in serine protease Heparin—physical characteristics Unfractionated heparin—longer polysaccaride chains stabilize IIa ATIII interactions and enhance IIa inactivation Pentasacchride Sequence—binds ATIII Low molecular weight heparin—preferential Xa inactivation ATIII IIa Xa ATIII Heparin—physical characteristicsSize matters IIa Xa fibrin Oligo mw effect pentasaccharide 1500 anti-Xa 18 5400 anti-IIa anti-Xa 24 7200 anti-IIa anti-Xa binds fibrin anti-HCII ATIII ATIII ATIII IIa Outpatient Clot management Choose between coumadin or LMW heparin for continued anticoagulation Coumadin: Initi