CURRENT Essentials of Critical Care.pdf

Chapter 4 Bleeding & Transfusions 45Thrombocytopenia■ Essentials of Diagnosis• Platelet count 50,000; petechiae or ecchymoses, or mild tosevere mucosal membrane or intracranial bleeding• Decreased production (bone marrow infiltration by infection ormalignancy, toxins, alcohol, drugs, aplastic anemia); increaseddestruction (idiopathic, DIC, drugs, hypersplenism, heparin-associatedthrombocytopenia, HELLP syndrome)• Spontaneous bleeding when platelet count 20,000, but highlyvariable; for same platelet count, platelet destruction less bleedingthan low production; qualitative platelet dysfunction worsensbleeding■ Differential Diagnosis• Pseudothrombocytopenia (platelet clumping in vitro due toEDTA anticoagulant)• Nonthrombocytopenic disorders of hemostasis (coagulopathy,vascular injury)• Vasculitis with palpable nonthrombocytopenic purpura• Thrombotic thrombocytopenic purpura (TTP) not associatedwith increased bleeding■ Treatment• Transfuse if 50,000/L and major surgical procedureplanned; 30,000/L, minor surgery or spontaneous bleeding; 5000–10,000, prophylactically• Transfuse at higher count if bleeding, fever, infection, renal failure,platelet dysfunction, low production (bone marrow failure);at lower counts if platelet destruction (transfusions minimallyuseful); transfusion contraindicated in TTP/HUS, heparin-inducedthrombocytopenia• Type-specific random-donor platelets, 6–8 units; expect5000–10,000/L increase per unit• Complications: volume overload, infections, sensitization toplatelets with decreased transfusion effectiveness• Other therapy: idiopathic thrombocytopenic purpura (corticosteroids,IgG); renal failure, von Willebrand disease (desmopressin),anemia (red cell transfusions)■ PearlIf platelet count does not rise by 5000–10,000 for each unit of platelets,suspect platelet destruction, such as ITP.ReferenceDrews RE, Weinberger SE: Thrombocytopenic disorders in critically ill patients.Am J Respir Crit Care Med 2000; 162:347. PMID: 10934051