CHAPTER 02- HEMATOLOGY.txt

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CHAPTER 02- HEMATOLOGY.txt
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2012-01-07 17:23:40
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  1. What are the 3 initial responses to vascular injury?
    • 1) vasoconstriction
    • 2) thrombin generation
    • 3) platelet adhesion
  2. Draw Coagulation cascade (p. 5)
  3. Prothrombin complex:
    • 1) X
    • 2) V
    • 3) Ca
    • 4) platelet factor 3
    • 5) prothrombin
    • 6) forms on platelets
    • 7) catalyzes the formation of thrombin
  4. What is the convergence point of both intrinsic and extrinsic pathways?
    Factor X
  5. What inhibits factor X
    Tissue factor pathway inhibitor
  6. What combines with platelets to form platelet plug --> hemostasis
    fibrin
  7. What helps crosslink fibrin?
    XIII
  8. Thrombin
    • 1) key to coagulation
    • 2) converts fibrinogen to fibrin and fibrin split products
    • 3) activates factors V and VIII
    • 4) activates platelets
  9. Anticoagulation (to follow)
  10. Antithrombin III
    • 1) key to anticoagulation
    • 2) binds and inhibits thrombin
    • 3) inhibits factors IX, X, XI
    • 4) Heparin binds AT-III
  11. Protein C:
    • Protein C
    • 1) vitamin K dependent
    • 2) degrades factors V and VIII
    • 3) degrades fibrinogen

    • Protein S
    • 1) vitamin K dependent
    • 2) protein C co-factor
  12. Fibrinolysis:
    • Tissue Plasminogen Activator:
    • 1- released from endothelium
    • 2- converts plasminogen to plasmin

    • Plasmin:
    • 1- degrades factors V and VIII, fibrinogen, and fibrin--> lose platelet plug

    • Alpha-2 antiplasmin-
    • natural inhibitor of plasmin, released from endothelium
  13. Which factor has the shortest half-life?
    VII
  14. Factors V and VIII:
    • 1) labile factors
    • 2) activity lost in stored blood
    • 3) activity not lost in FFP
  15. What is the only factor not synthesized in the liver
    VIII, only factor not synthesized in liver (synthesized in endothelium)
  16. What are the vitamin K- dependent factors?
    II, VII, IX, and X; protein C + S
  17. How long does it take for vitamin k to take effect?
    takes 6 hours
  18. How long does it take for FFP to take effect?
    effect is immediate, lasts for 6 hours
  19. Whats the name for factor II?
    prothrombin
  20. Normal half-life of:
    RBC:
    Platelets:
    PMNs:
    • RBC: 120 days
    • Platelets: 7 days
    • PMNs: 1-2 days
  21. Prostacyclin
    • 1) PGI2
    • 2) from endothelium
    • 3) decreases platelet aggregation and promotes vasodilation (antagonistic to TXA2)
  22. Thromboxane
    • 1) TXA2
    • 2) from platelets
    • 3) increases platelet aggregation and promotes vasoconstriction
    • 4) triggers release of calcium in platelets --> exposes GpIIb/IIIa and causes platelet-to-platelet binding, platelet-to-collagen binding
    • 5) activates PIP system to further increase calcium
  23. Cryoprecipitate
    contains highest concentration of VWF and VIII; used in von willibrand's disease and hemophilia A (factor VIII deficiency), also contains fibrinogen
  24. FFP
    has high levels of all factors (including labile factors V and VIII), protein C, protein S, and AT-III
  25. DDAVP and conjugated estrogens
    causes release of VIII and vWF from endothelium
  26. What does PT measure?
    • 1) PT- measures II, V, VII, and X; fibrinogen
    • 2) Best for synthetic liver activity
  27. What does PTT measure?
    PTT- measures most factors except VII and XIII (thus does not pick up factor VII deficiency); also measures fibrinogen
  28. What range should PTT be if you want anticoagulation?
    PTT 60-90 sec for anticoagulation
  29. ACT
    • 1) activated clotting time
    • 2) want ACT 150-200 sec for routine anticoagulation, 460 sec for cardiopulmonary bypass
  30. What INR ranges are a contraindication for procedures?
    INR >1.5- relative contraindication to performing surgical procedures

    INR >1.3- relative contraindication to central line placement, percutaneous needle biopsies, and eye surgery
  31. What is the most common cause of surgical bleeding?
    incomplete hemostasis
  32. Von Willebrand's disease
    • 1) most common congenital bleeding disorder
    • 2) types I and II are autosomal dominant; type III is autosomal recessive
    • 3) vWF links GpIb receptor on platelets to collagen
    • 4) PT normal, PTT can be normal or abnormal
    • 5) have long bleeding time (ristocetin test)
    • 6) type I is most common (70% of cases) and often only has mild symptoms
    • 7) Type III causes most severe bleeding
    • 8) Type I and III- reduced quantity of circulating vWF
    • Tx: recombinant VIII:vWF, DDAVP, cryoprecipitate, conjugated estrogens
    • 9) Type II- defect in vWF molecule itself, have enough vWF but does not work well
    • Tx: recombinant VIII: vWF, cryoprecipitate

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