Tintinalli's Emergency Medicine - Just the Facts, 3ed.

136. AQUIRED BLEEDING DISORDERS

Aaron Barksdale

ACQUIRED PLATELET DEFECTS

PATHOPHYSIOLOGY

images Acquired platelet abnormalities include qualitative (dysfunctional) and quantitative (thrombocytopenia) defects.

images Thrombocytopenia may be a result of decreased platelet production, increased platelet destruction, increased platelet loss, and splenic sequestration.

CLINICAL FEATURES

images Bleeding due to thrombocytopenia commonly presents as petechiae and mucosal bleeding (gingival, epistaxis).

images Additional findings may include purpura, hemoptysis, menorrhagia, hematuria, or hematochezia.

images Deep tissue bleeding is uncommon.

DIAGNOSIS AND DIFFERENTIAL

images Causes of decreased platelet production include marrow infiltration, aplastic anemia, drugs, viral infections, and chronic alcohol use.

images Causes of increased platelet destruction include idiopathic thrombocytopenic purpura (ITP), throm-botic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS), disseminated intravascular coagulation (DIC), and viral infection, drugs, and HELLP syndrome.

images Thrombocytopenia may also be the result of acute hemorrhage, hemodialysis, and splenic sequestration.

images Qualitative platelet disorders include uremia, liver disease, drugs (aspirin, NSAIDs, clopidogrel), antiplate -let antibodies, DIC, and myeloproliferative disorders.

EMERGENCY DEPARTMENT CARE AND DISPOSITION

images Initial laboratory testing should include a CBC with peripheral smear.

images Consider consultation with hematologist. Some conditions may worsen with platelet transfusion (DIC and TTP).

images Consider platelet transfusion when platelet count <10,000/mm3 or when active bleeding and platelets <50,000/mm3.

images Patient’s with ITP and platelets >50,000/mm3 do not require treatment.

images Patients with ITP and platelet count <20,000 to 30,000/mm3 or active bleeding and platelets <50,000 typically require treatment.

images The initial treatment of ITP is usually corticosteroids, prednisone 60 to 100 milligrams PO daily.

images Severe cases of ITP may require IV immunoglobu-lin, 1 gram/kg/d.

BLEEDING IN LIVER DISEASE

PATHOPHYSIOLOGY

images Liver disease increases the risk of bleeding for multiple reasons, including decreased synthesis of vitamin K-dependent coagulation factors (II, VII, IX, and X), thrombocytopenia, and increased fibrinolysis.

EMERGENCY DEPARTMENT CARE AND DISPOSITION

images Patients with liver disease and active bleeding should receive vitamin K, 10 milligrams PO or IV.

images Patients with severe bleeding or prior to invasive procedure should receive fresh frozen plasma 15 millilit-ers/kg IV to temporarily replace coagulation factors.

images Patients with active bleeding and fibrinogen levels <100 milligrams/dL, administer cryoprecipitate, 1 unit/5 kg IV.

images Platelet transfusion may be indicated when severe bleeding and associated thrombocytopenia.

images Desmopressin 0.3 microgram/kg SC or IV may shorten bleeding times in some patients.

BLEEDING IN RENAL DISEASE

PATHOPHYSIOLOGY

images Bleeding in renal disease is the result of a variety of hemostatic abnormalities including platelet dysfunction due to uremic toxins, deficiency of coagulation factors, and thrombocytopenia.

EMERGENCY DEPARTMENT CARE AND DISPOSITION

images Treat acute bleeding with the transfusion of packed red blood cells when indicated.

images Hemodialysis improves platelet function transiently for 1 to 2 days.

images Desmopressin 0.3 microgram/kg SC or IV shortens bleeding time in most patients.

images Conjugated estrogen 0.6 milligram/kg IV improves the bleeding time and active bleeding in the majority of uremic patients.

images Platelet transfusions and cryoprecipitate are indicated for life-threatening bleeding only, and are to be used in conjunction with the previously listed therapies.

DISSEMINATED INTRAVASCULAR COAGULATION

PATHOPHYSIOLOGY

images DIC is an acquired syndrome that results from the activation of both the coagulation and fibrinolytic systems.

CLINICAL FEATURES

images The complications of DIC are related to both bleeding and thrombosis, although one usually predominates.

images The clinical features include bleeding from venipunc-ture sites and the GI or GU tract, petechiae and ecchy-mosis, thrombosis, purpura fulminans, and multiple organ failure.

images Patients may also display mental status changes, focal ischemia of the extremities, oliguria, renal cortical necrosis, and adult respiratory distress syndrome (ARDS).

DIAGNOSIS AND DIFFERENTIAL

images The diagnosis is based on the history, clinical presentation, and associated laboratory abnormalities.

images The common conditions associated with DIC are listed in Table 136-1.

images Refer to Table 136-2 for the laboratory abnormalities associated with DIC.

TABLE 136-1 Common Conditions Associated with Disseminated Intravascular Coagulation (DIC)

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TABLE 136-2 Laboratory Abnormalities Characteristic of Disseminated Intravascular Coagulation (DIC)

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EMERGENCY DEPARTMENT CARE AND DISPOSITION

images Treatment should focus on the underlying illness and hemodynamic support (IV fluid resuscitation, transfusion of red bloods cells, and vasopressors and inotropic agents).

images Administer cryoprecipitate 1 unit/5 kg IV to patients with active bleeding until fibrinogen levels are between 100 and 150 milligrams/dL.

images Transfuse platelets if counts are <20,000/mm3 or <50,000/mm3 with active bleeding.

images Transfuse fresh frozen plasma 15 mL/kg IV if active bleeding.

images Patients with active bleeding, administer vitamin K 10 milligrams IV/PO and folate 1 milligram IV

images The role of heparin remains unclear.

CIRCULATING INHIBITORS OF COAGULATION

EPIDEMIOLOGY

images Acquired inhibitors of coagulation are very rare. There are 1.4 cases per 1 million persons per year.

images Most cases of acquired hemophilia occur in the elderly.

PATHOPHYSIOLOGY

images Circulating anticoagulants are antibodies directed against one or more of the coagulation factors.

images The two most common circulating anticoagulants are factor VIII inhibitor (a specific inhibitor directed only against factor VIII) and antiphospholipid antibodies, including lupus anticoagulant and anticardiolipin antibody (nonspecific inhibitors directed against several coagulation factors).

CLINICAL FEATURES

images Patients with factor VIII inhibitor may present with massive spontaneous bruises, ecchymosis, and hematomas.

images Patients with lupus anticoagulant and anticardiolipin antibodies typically develop symptoms associated with thrombosis.

DIAGNOSIS AND DIFFERENTIAL

images Coagulation studies in patients with factor VIII inhibitor will display a normal PT, normal thrombin clot time, and a prolonged PTT that does not correct with mixing studies.

images A factor VIII–specific assay will show low or absent factor VIII activity.

EMERGENCY DEPARTMENT CARE AND DISPOSITION

images Patients with factor VIII inhibitor and acute bleeding should be managed in conjunction with a hematologist.

images Treatment options include factor VIII, factor IX complex, recombinant factor VIIa, desmopressin acetate, prothrombin complex, and plasmapheresis.

CLOTTING DISORDERS

PATHOPHYSIOLOGY

images Hypercoagulable states may be inherited or acquired (see Table 136-3).

TABLE 136-3 Hypercoagulable States

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images Thrombosis formation may occur in the venous and/or arterial circulation systems.

images “Virchow’s triad” increases the risk of venous thrombus formation and includes hypercoagulability, venous stasis, and endothelial injury.

CLINICAL FEATURES

images Features suggestive of a clotting disorder include early thrombosis (<45 years old), recurrent thrombotic events, family history of thrombosis, recurrent fetal loss, and thrombosis in unusual locations (mesenteric, cerebral, axillary, or portal veins).

images Patients may present with signs of a deep venous thrombosis (unilateral swollen and potentially painful extremity).

images Patients may present with signs of a pulmonary embolus (dyspnea, tachycardia, hemoptysis, hypoxia, dizziness, and in severe cases hypotension).

images Other potential presenting symptoms include abdominal pain (mesenteric thrombus and/or ischemia), portal hypertension (portal vein thrombosis), or neurologic symptoms (cerebral vein thrombosis or acute CVA).

DIAGNOSIS AND DIFFERENTIAL

images Laboratory tests for hypercoagulable conditions are time consuming, highly specialized, and it is unlikely to acquire results in the acute ED setting.

images A CBC with complete differential and coagulation studies should be ordered.

images Consider heparin-induced thrombocytopenia (HIT) in patients with a drop in platelet count >50% after 5 to 15 days of initiating heparin therapy.

images See Table 136-3 for the differential diagnosis of hypercoagulable states.

EMERGENCY DEPARTMENT CARE AND DISPOSITION

images Patients with new or worsening thrombosis should be started on low molecular weight or unfractionated heparin therapy, and hospital admission.

images In patients with HIT, heparin must be stopped. Another anticoagulant (lepirudin, argatroban, danaparoid) should be initiated in consultation with a hematologist.


For further reading in Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7th ed., see Chapter 228, “Acquired Bleeding Disorders,” by Sally A. Santen and Rubin R. Hemphill, and Chapter 229, “Clotting Disorders, “by Jessie G. Nelson and Robin R. Hemphill.