02a Surgical hemostasis

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    07-May-2015

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<ul><li>1.Hemostasis in the SurgicalPatientAmr Aborahma , MDLecturer of Vascular Surgery</li></ul> <p>2. WHAT ARE YOUR EXPECTATIONS ? 3. Hemostasis in the Surgical Patient Is It An Important Topic ? 4. From your point of view !! 5. Does All bleeding (eventually) stops ? 6. BleedingClottingHemostasisUnder normal conditions, blood circulatesthrough the intact vasculature withoutthrombus formation or haemorrhage 7. HemostasisState of fluid equilibrium within the blood vessels Vessels CoagulationProteinsPlatelets Fibrinolysis/ Inhibitors 8. Hemostasis A process which causes bleeding to stopPrimary Hemostasis Arteriolar vasoconstriction Formation of platelet plugSecondary Hemostasis Activation of coagulation cascade Formation of permanent plug 9. Constriction of vesselsThere are 2 mechanisms for vesselconstriction: Local smooth muscle contractile response Thromboxane A2 release from endothelium 10. Formation of platelet plugExposure of the subendothelial layers cause plateletsto adhere.They release ADP and TxA2, inducing further plateletaggregation and activationAdhesion requires von Willebrand factor (vWf) fromthe subendothelial layers. 11. The time taken for platelet plug to form(Bleeding Time - BT) gives a non-specificindication of: The state of the vascular endothelium The number of platelets in the circulation The platelets are functioning correctly (canrelease granules and produce pseudopodia) Demonstrates the presence of vWF 12. Coagulation Factors Factor IFibrinogen Factor II Prothrombin Factor IIITissue Thromboplastin Factor IV Calcium Ions Factor VLabile Factor, Proaccelerin Factor VIIStable Factor, Proconvertin Factor VIII Antihemophilic Factor Factor IX Christmas Factor Factor XStuart-Prower Factor Factor XI Plasma Thromboplastin Antecedent Factor XIIHageman Factor Factor XIII Fibrin Stabilizing FactorAll coagulation factors are made in theliver, except for vWF 13. Clotting cascadeIntrinsic Pathway All factors occur from within the circulation in vivo, the pathway is triggered by exposure of "contact factors"to collagen or basement membrane at the site of injury or aforeign substance such as a prosthetic deviceExtrinsic Pathway Requires tissue thromboplastin to be released from damagedcells (outside the circulation) Both pathways lead to the activation of prothrombin(factor II) Final common pathway converts fibrinogen to fibrin 14. Clotting cascade 15. Natural inhibitors of the coagulation cascade Thrombomodulin Antithrombin III Tissue factor pathway inhibitor Protein C Protein S 16. Which is moving? 17. Natural inhibitors of the coagulation cascade Antithrombin III is a large protease inhibitor that inhibitsthrombin and factors IXa, Xa, XIa, and XIIa but does notinhibit thrombin within clots Heparin accelerates the reaction time of antithrombin III 1000 fold 18. Natural inhibitors of the coagulation cascade Protein C and Protein S Vitamin K-dependent serine proteases synthesizedin the liver Circulate as inactive forms (zymogens) Protein C inhibits the activity of factors Va and VIIIa Protein S cofactor that potentiates the action of Protein C 19. Take A Break !!!Watch this video 20. Defects of HemostasisCongenital disorders Hemophilia A,B von Willebrand diseaseAcquired disordersHepatic disordersDICVitamin K defeciencyAnticoagulantsMassive blood transfusionPlatelet disorders 21. Preoperative screening for bleeding risk Complete history and physicalEckman et al. Ann Intern Med Vol 138, No 5 22. Preoperative screening for bleeding risk Incidence of a significant hereditary deficiency of a coagulation factor is low (1 per 10,000-40,000) approximately 1/3 of these are asymptomatic Acquired deficiencies of factors should be suspected in the presence of advance hepatic disease, malabsorption, or malnutrition 23. Hemostasis Screening TestsBleeding TimeClotting Time-Vascular Platelet Count -Platelet PT -Coagulation factors-Fibrinolysis APTT TT Euglobulin Clot Lysis Time D = Dimer 24. Clinical testing and preoperative screening Prothrombin time (PT) measure extrinsic and common pathways affected by low concentrations of fibrinogen, prothrombin and factors II, V, VII, X Activated partial thomboplastin time (aPTT) measures intrinsic and common pathways deficiencies in all clotting factors except factors VII and XIII may prolong the aPTT 25. Surgical hemostasis 26. Stopping the bleedingDirect pressure.More direct pressure. Pack. Pack. Pack.Electrocautery.Ligate vessel 27. MethylcelluloseGelfoam Absorbable Liquefies in 2-5days Serves as ascaffold forcoagulation 28. Oxidized regenerated celluloseSurgicel Binds platelets and chemically precipitates fibrin 29. Microfibrillar collagenDecellularized bovine sourceStimulates latelet adhesionStops venous oozeAbsorbed in 90 days 30. Thrombin + Gelfoam + CaClThrombin for cleavage/activationGelfoam as matrixVery useful in vascular surgery 31. Fibrin glueTiseelFDA approved in 1998Concentrated fibrinogen and f VIIIThrombin and calciumAprotinin to prevent clot dissolutionTakes time to prepareGood for diffuse oozing, needle punctures,parenchymal injuries 32. Questions 33. What is your feedback? 34. Thank YouEmail: amr.aborahma@gmail.com </p>