02a Surgical hemostasis


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02a Surgical hemostasis

  1. 1. Hemostasis in the Surgical Patient Amr Aborahma , MD Lecturer of Vascular Surgery
  3. 3. Hemostasis in the Surgical Patient Is It An Important Topic ?
  4. 4. From your point of view !!
  5. 5. Does All bleeding (eventually) stops ?
  6. 6. Bleeding Clotting HemostasisUnder normal conditions, blood circulatesthrough the intact vasculature withoutthrombus formation or haemorrhage
  7. 7. HemostasisState of fluid equilibrium within the blood vessels Vessels Coagulation Proteins Platelets Fibrinolysis/ Inhibitors
  8. 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. 9. Constriction of vesselsThere are 2 mechanisms for vesselconstriction:– Local smooth muscle contractile response– Thromboxane A2 release from endothelium
  10. 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. 11. The time taken for platelet plug to form (Bleeding Time - BT) gives a non-specific indication of:• The state of the vascular endothelium• The number of platelets in the circulation• The platelets are functioning correctly (can release granules and produce pseudopodia)• Demonstrates the presence of vWF
  12. 12. Coagulation Factors Factor I Fibrinogen Factor II Prothrombin Factor III Tissue Thromboplastin Factor IV Calcium Ions Factor V Labile Factor, Proaccelerin Factor VII Stable Factor, Proconvertin Factor VIII Antihemophilic Factor Factor IX Christmas Factor Factor X Stuart-Prower Factor Factor XI Plasma Thromboplastin Antecedent Factor XII Hageman Factor Factor XIII Fibrin Stabilizing FactorAll coagulation factors are made in theliver, except for vWF
  13. 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 a foreign substance such as a prosthetic deviceExtrinsic Pathway– Requires tissue thromboplastin to be released from damaged cells (outside the circulation) Both pathways lead to the activation of prothrombin(factor II) Final common pathway converts fibrinogen to fibrin
  14. 14. Clotting cascade
  15. 15. Natural inhibitors of the coagulation cascade  Thrombomodulin  Antithrombin III  Tissue factor pathway inhibitor  Protein C  Protein S
  16. 16. Which is moving?
  17. 17. Natural inhibitors of the coagulation cascade Antithrombin III is a large protease inhibitor that inhibits thrombin and factors IXa, Xa, XIa, and XIIa but does not inhibit thrombin within clots  Heparin accelerates the reaction time of antithrombin III 1000 fold
  18. 18. Natural inhibitors of the coagulation cascade Protein C and Protein S  Vitamin K-dependent serine proteases synthesized in 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. 19. Take A Break !!!Watch this video
  20. 20. Defects of HemostasisCongenital disorders Hemophilia A,B von Willebrand diseaseAcquired disorders Hepatic disorders DIC Vitamin K defeciency Anticoagulants Massive blood transfusion Platelet disorders
  21. 21. Preoperative screening for bleeding risk Complete history and physical Eckman et al. Ann Intern Med Vol 138, No 5
  22. 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. 23. Hemostasis Screening Tests• Bleeding Time• Clotting Time -Vascular Platelet Count -Platelet PT -Coagulation factors -Fibrinolysis APTT TT Euglobulin Clot Lysis Time D = Dimer
  24. 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. 25. Surgical hemostasis
  26. 26. Stopping the bleedingDirect pressure.More direct pressure. Pack. Pack. Pack.Electrocautery.Ligate vessel
  27. 27. MethylcelluloseGelfoam– Absorbable– Liquefies in 2-5 days– Serves as a scaffold for coagulation
  28. 28. Oxidized regenerated celluloseSurgicel – Binds platelets and chemically precipitates fibrin
  29. 29. Microfibrillar collagenDecellularized bovine sourceStimulates latelet adhesionStops venous oozeAbsorbed in 90 days
  30. 30. Thrombin + Gelfoam + CaClThrombin for cleavage/activationGelfoam as matrixVery useful in vascular surgery
  31. 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. 32. Questions
  33. 33. What is your feedback?
  34. 34. Thank YouEmail: amr.aborahma@gmail.com