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Chapter 85: Disseminated Intravascular Coagulation

INTRODUCTION

  • Disseminated intravascular coagulation (DIC) is a syndrome that is characterized by systemic intravascular activation of coagulation, leading to fibrin deposition in the microvasculature and small- and mid-size vessels, thereby contributing to organ dysfunction. Simultaneously, ongoing consumption of platelets and coagulation factors leads to thrombocytopenia and impaired coagulation and may result in serious bleeding complications.

  • DIC never occurs by itself but is always secondary to an underlying cause. Table 85–1 lists the most frequently occurring disorders know to be associated with DIC.

TABLE 85–1CLINICAL CONDITIONS THAT MAY BE COMPLICATED BY DISSEMINATED INTRAVASCULAR COAGULATION
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TABLE 85–1 CLINICAL CONDITIONS THAT MAY BE COMPLICATED BY DISSEMINATED INTRAVASCULAR COAGULATION

Infectious diseases: purpura fulminans

Malignancy

 Solid tumors

 Leukemias

Trauma

 Brain injury

 Burns

Liver diseases

Heat stroke

Severe allergic/toxic reactions

 Snake bites

Vascular abnormalities/Hemangiomas

 Kasabach-Merritt syndrome

 Other vascular malformations

 Aortic aneurysms

Severe immunologic reactions (eg, transfusion reaction)

Obstetrical conditions

 Abruptio placentae

 Amniotic fluid embolism

 Preeclampsia/eclampsia

 HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome

 Sepsis during pregnancy

 Acute fatty liver

Source: Williams Hematology, 9th ed, Chap. 129, Table 129–1.

PATHOGENESIS

  • The pathogenesis of DIC is diagrammed in Figure 85–1.

  • Exposure of blood to tissue factor appears to be the principal mechanism of activation of coagulation. Tissue factor may be expressed by mononuclear cells or by the endothelium.

  • Other stimuli include activation of factor Xa by a cancer procoagulant, snake envenomation, and tissue/cellular debris in patients with massive trauma or pancreatitis.

  • Activation of coagulation is insufficiently balanced by physiologic anticoagulant pathways (eg, antithrombin, protein C system) and a downregulation of endogenous fibrinolysis due to high levels of the fibrinolysis inhibitor plasminogen activator inhibitor type 1 (PAI-1).

FIGURE 85–1

Schematic presentation of pathogenetic pathways involved in the activation of coagulation in disseminated intravascular coagulation (DIC). In DIC, both perturbed endothelial cells and activated mononuclear cells may produce proinflammatory cytokines that mediate coagulation activation. Activation of coagulation is initiated by tissue factor expression on activated mononuclear cells and endothelial cells. In addition, downregulation of physiologic anticoagulant mechanisms and inhibition of fibrinolysis by endothelial cells further promote intravascular fibrin deposition. PAI-1, plasminogen-activator inhibitor type 1. (Source: Williams Hematology, 9th ed, Chap. 129, Fig. 129–1.)

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CLINICAL FEATURES

  • Clinical features are related to the underlying disorder, to the DIC, or both.

  • Bleeding manifestations have been observed in about 25% of cases in several series.

  • Persistent bleeding from venipuncture sites or other skin wounds occurs frequently.

  • Hemorrhage may be life-threatening.

  • Extensive organ dysfunction may be induced by microvascular thrombi, or by venous and/or arterial thromboembolism.

  • Organ dysfunction may manifest as acute renal failure (renal cortical ischemia and acute tubular necrosis occur frequently), hepatic dysfunction, and respiratory insufficiency due to acute respiratory distress syndrome.

  • Coma, delirium, focal neurologic symptoms, and signs of ...

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