Chapter 14 Alterations in Hemostasis and Blood Coagulation PDF

Chapter 14 Alterations in Hemostasis and Blood Coagulation Dr. Tashea S. Hilliard, Associate Professor Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.  Learning Objectives 1) Describe how platelets and factors of...

Chapter 14 Alterations in Hemostasis and Blood Coagulation Dr. Tashea S. Hilliard, Associate Professor Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.  Learning Objectives 1) Describe how platelets and factors of the clotting cascade contribute to hemostasis. 2) Explain what findings from the patient history, physical examination, or laboratory studies would indicate a potential bleeding disorder. 3) Explain how laboratory tests used to differentiate the various coagulation disorders. 4) Describe the vascular alterations resulting in abnormalities of hemostasis. 5) Identify the common causes of platelet deficiencies, excesses, and dysfunction. 6) Identify the common causes of inherited and acquired disorders of coagulation. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.  Hemostasis is the arrest of bleeding or prevention of blood loss after blood vessel injury Involves the vessel wall, circulating platelets, and plasma coagulation proteins The Process of Hemostasis Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.  Included in patient history and physical exam Determine if problem exists and underlying cause so appropriate management is initiated Especially indicated for: Personal/family history of bleeding disorder During active bleeding that is unresponsive to standard interventions Screening before surgery Ongoing evaluation of anticoagulation therapy Evaluation of Hemostasis and Coagulation Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Clinical Assessment Personal/family history of bleeding disorder Systemic diseases that may be involved Medication history Physical findings such as petechiae, purpura, ecchymosis, hematoma, hemarthrosis, telangiectasia, and occult or frank bleeding Evaluation of Hemostasis and Coagulation (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Laboratory Tests Evaluation of primary and secondary hemostasis CBC to identify anemia Platelet count to identify number of platelets Peripheral smear indicates the number and gross morphologic characteristics of platelet function Bleeding time evaluates vascular status and platelet function PT/INR assesses the extrinsic pathway of coagulation aPTT assesses the intrinsic pathway Evaluation of Hemostasis and Coagulation (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.  Primary cause of bleeding is a problem with the vascular component of primary hemostasis May be acquired or inherited Vascular and Platelet Disorders Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Vascular Disorders Vascular purpura Abnormality of the vessels or tissues Purpura (patches of petechiae) are present Allergic purpura: autoimmune process Ehlers-Danlos syndrome: deficient collagen and elastin Vitamin C deficiency: defective collagen synthesis Aging: loss of subcutaneous fat and changes in connective tissue Vascular and Platelet Disorders (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Vascular Purpura Diagnosis is one of exclusion after platelet and coagulation disorders are ruled out Tourniquet (Rumpel-Leede) test may be used Treatment is geared toward removing and avoiding the causative agent Vascular and Platelet Disorders (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Hereditary Hemorrhagic Telangiectasia (Osler-Weber-Rendu Disease) Autosomal dominant trait Vessel wall composed of single layer of endothelium Multiple telangiectases, repeated episodes of bleeding, or a family history in both sexes Supportive tx with topical hemostatic agents, cauterization, iron replacement, laser therapy Vascular and Platelet Disorders (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Platelet Disorders Primary cause of bleeding is an abnormality in the quantity or quality of platelets May be acquired or inherited Vascular and Platelet Disorders (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Thrombocytopenia General mechanisms Decreased platelet production Decreased platelet survival Splenic sequestration Intravascular dilution of circulating platelets Low platelet count, prolonged bleeding time, abnormal peripheral smear Treatment based on identified cause Vascular and Platelet Disorders (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Thrombocytosis Platelet count greater than 400,000/mm3 Transitory—due to stress/physical exercise Primary—polycythemia vera or chronic granulocytic leukemia Secondary—response to hemorrhage, disease process, or splenectomy Treatment reserved for primary etiologies with cytotoxic agents and antiplatelet therapy Vascular and Platelet Disorders Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Qualitative Platelet Disorders Ability of platelets to function in the hemostatic process is abnormal Inherited disorders include Bernard-Soulier syndrome, von Willebrand disease, and thrombasthenia Acquired disorders more common (drug-induced, renal failure, hematologic disease) Treatment based on underlying disorder and may require platelet transfusion Vascular and Platelet Disorders (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.  Coagulopathies are defects of the normal clotting mechanism Results can include: Bleeding from a problem with the formation, stabilization or lysis of the fibrin clot Excessive clot formation due to inappropriate activation of the coagulation cascade Coagulation Disorders Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Hemophilia The most common inherited coagulation disorder resulting in excessive bleeding Hemophilia A—factor VIII deficiency Hemophilia B—factor IX deficiency Treatment includes patient/family education Hemophilia A: cryoprecipitate or factor VIII concentrate Hemophilia B: fresh frozen plasma or cryoprecipitate Coagulation Disorders (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Von Willebrand Disease Autosomal dominant disorder of factor VIII carrier protein and platelet dysfunction Causes excessive bleeding Treatment with desmopressin, which releases von Willebrand factor and factor VII from vascular endothelial cells; cryoprecipitate and humate-P used to manage severe bleeding Coagulation Disorders (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Vitamin K Deficiency Bleeding in Infancy Deficiency of vitamin K–dependent coagulation factors (II, VII, IX, and X) Evidence of bleeding occurs early in life (melena, hematuria, intracranial hemorrhage, hypovolemic shock) Prophylactic administration of vitamin K to the newborn largely eliminates this coagulation disorder Coagulation Disorders (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Acquired Vitamin K Deficiency May occur with malnutrition, malabsorption, chronic hepatic disease, antibiotic therapy, oral anticoagulation therapy Results in excessive bleeding Parenteral administration of vitamin K is used for treatment Coagulation Disorders (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Disseminated Intravascular Coagulation (DIC) Acquired hemorrhagic syndrome in which clotting and bleeding occur simultaneously Fibrinogen level and platelet count decreased Increased bleeding time Elevated PT/INR/aPTT/D-dimer Treatment: removal/correction of underlying cause Coagulation Disorders (Cont.) Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc. Hepatic Disease Coagulopathies result from: Impaired absorption of vitamin K Decreased synthesis of fibrinogen, factors V and XI Inability to remove activated coagulation factors and fibrinolytic proteins from circulation Altered production of inhibitors of coagulation Treatment includes vitamin K administration; transfusion of platelets, fresh frozen plasma, or whole blood Coagulation Disorders Elsevier items and derived items © 2010, 2005 by Saunders, an imprint of Elsevier Inc.