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LEARNING OBJECTIVES

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LEARNING OBJECTIVES

Upon completion of this chapter, the reader will be able to:

  1. Describe the basics of the regulation of hemostasis and thrombosis.

  2. Determine which factor replacement preparation is appropriate in a given clinical situation.

  3. Calculate an appropriate factor-concentrate dose for a product, given the percentage correction desired based on clinical situation.

  4. List the complications from hemophilia bleeding episodes.

  5. Choose appropriate treatment strategy for patients with factor VIII or IX inhibitors.

  6. Devise a treatment plan for a patient with a specific variant of von Willebrand's disease (vWD).

  7. Describe various recessively inherited coagulation disorders (RICDs) and role of specific factor replacement in RICD management.

  8. Formulate an appropriate treatment plan based on presentation of disseminated intravascular coagulation (DIC).

  9. Recommend first-line and a second-line treatment approaches for immune thrombocytopenic purpura (ITP).

  10. Identify basic clinical features, causes, and management of thrombotic thrombocytopenic purpura (TTP).

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KEY CONCEPTS

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  • Image not available. IV replacement with recombinant or plasma-derived products to treat or prevent bleeding is the primary treatment of hemophilia.

  • Image not available. Patients with type 1 von Willebrand's disease (vWD) unresponsive to desmopressin, patients with types 2 and 3 vWD, and major surgery patients require replacement therapy with plasma-derived intermediate- and high-purity factor VIII, virus-inactivated factor VIII concentrate containing von Willebrand's factor (vWF).

  • Image not available. The primary treatment of recessively inherited coagulation disorders (RICDs) is single-donor fresh-frozen plasma (FFP) that contains all coagulation factors.

  • Image not available. The cornerstone of the management of disseminated intravascular coagulation (DIC) is aggressive treatment of the underlying primary illness. Supportive measures may be used as necessary; however, owing to the heterogeneity of the DIC etiology, treatment should be guided by predominant symptoms (bleeding or clotting).

  • Image not available. The treatment of immune thrombocytopenic purpura (ITP) is determined by the symptom severity. In some cases, no therapy is needed.

  • Image not available. The present standard of treatment for thrombotic thrombocytopenic purpura (TTP) is urgent plasma exchange (PEX). If PEX is unavailable, treatment with plasma infusion and glucocorticoids is indicated until PEX is available.

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INTRODUCTION

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Components of the Hemostatic System

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Following endothelial injury, vessel-wall response involves vasoconstriction, platelet plug formation, coagulation, and fibrinolysis regulation. In normal circumstances, platelets circulate in the blood in an inactive form. After injury, platelets undergo activation, which consists of (a) adhesion to the subendothelium, (b) secretion of granules containing chemical mediators (e.g., adenosine diphosphate, thromboxane A2, thrombin, etc.), and (c) aggregation. Chemical factors released from the injured tissue and platelets stimulate the coagulation cascade and thrombin formation. In turn, thrombin catalyzes the conversion of fibrinogen to fibrin and its subsequent incorporation into plug.

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The coagulation system consists of intrinsic and extrinsic pathways. Both pathways are composed of a series of enzymatic reactions that ultimately produce thrombin, fibrin, and a stable clot. In parallel with the coagulation, the fibrinolytic system is activated locally. Plasminogen is converted to plasmin, which dissolves the fibrin mesh (Fig. 67–1).1

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FIGURE 67–1.

Cascade model of ...

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