Hemostasis Overview and Steps
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Hemostasis Overview and Steps

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Questions and Answers

Which of the following is a sign of bleeding that may require medical attention?

  • Weight loss
  • Increased appetite
  • Dry mouth
  • Bruising (correct)

    • What is the primary function of Idarucizumab?

  • To act as an anticoagulant
  • To enhance platelet aggregation
  • To reverse the effects of dabigatran (correct)
  • To promote blood clotting

    • Which factor does rivaroxaban primarily inhibit?

  • Factor I
  • Factor Xa (correct)
  • Factor IIa
  • Factor VII

    • What distinguishes direct oral factor Xa inhibitors from traditional anticoagulants like warfarin?

    <p>Rapid onset of action</p> Signup and view all the answers

    Which of these substances is NOT involved in platelet function regulation?

    <p>Vitamin K</p> Signup and view all the answers

    What is the mechanism of action for Warfarin?

    <p>Inhibits vitamin K synthesis</p> Signup and view all the answers

    Which monitoring parameter is associated with Heparin therapy?

    <p>aPTT</p> Signup and view all the answers

    What is the primary use of Heparin?

    <p>Prevention of venous thrombosis</p> Signup and view all the answers

    Which of the following is a common side effect of Warfarin?

    <p>Bleeding</p> Signup and view all the answers

    What is the recommended INR target range for patients on Warfarin?

    <p>2.0-3.0</p> Signup and view all the answers

    What antidote is used for Warfarin toxicity?

    <p>Vitamin K</p> Signup and view all the answers

    How is Heparin primarily administered in a clinical setting?

    <p>IV or subcutaneously</p> Signup and view all the answers

    What is a contraindication for administering Heparin?

    <p>Administering IM injections</p> Signup and view all the answers

    What is the first step in the hemostasis process?

    <p>Vascular phase</p> Signup and view all the answers

    What role do platelets play during the platelet phase of hemostasis?

    <p>They aggregate to form a clot</p> Signup and view all the answers

    What is fibrin's role in hemostasis?

    <p>To form a stable clot by trapping blood cells</p> Signup and view all the answers

    Which pathway is initiated by material outside of the blood during coagulation?

    <p>Extrinsic pathway</p> Signup and view all the answers

    What occurs during the clot retraction stage of hemostasis?

    <p>Platelets begin to contract the clot</p> Signup and view all the answers

    Which of the following statements is true about the intrinsic pathway?

    <p>It is a slower process than the extrinsic pathway</p> Signup and view all the answers

    What is the final product formed during the coagulation phase?

    <p>Fibrin</p> Signup and view all the answers

    How does hemostasis maintain balance in the body?

    <p>By balancing clot formation and breakdown</p> Signup and view all the answers

    Which vitamin is mainly required for the biological activity of prothrombin?

    <p>Vitamin K</p> Signup and view all the answers

    What is Hemophilia A primarily caused by?

    <p>Factor VIII deficiency</p> Signup and view all the answers

    Which vitamin is synthesized by human intestinal bacteria?

    <p>Vitamin K2</p> Signup and view all the answers

    Von Willebrand disease is characterized by a deficiency in which of the following?

    <p>Von Willebrand factor</p> Signup and view all the answers

    Hemophilia A occurs in approximately how many live births?

    <p>1 in 5,000</p> Signup and view all the answers

    What percentage of patients have Type 1 Von Willebrand disease?

    <p>60% - 80%</p> Signup and view all the answers

    Which of the following is a fat-soluble vitamin crucial for blood clotting?

    <p>Vitamin K</p> Signup and view all the answers

    Which factors require bile salts for absorption from the intestinal tract?

    <p>Vitamins K1 and K2</p> Signup and view all the answers

    What is the primary mechanism of action for antiplatelet drugs?

    <p>Interfere with platelet aggregation</p> Signup and view all the answers

    Which of the following is a TXA2 synthesis blocker?

    <p>Aspirin</p> Signup and view all the answers

    What common side effect is associated with Aspirin?

    <p>Increased incidence of hemorrhagic stroke</p> Signup and view all the answers

    Which antiplatelet drug is safer compared to Ticlopidine?

    <p>Clopidogrel</p> Signup and view all the answers

    What is a potential adverse effect of Ticlopidine?

    <p>Thrombotic thrombocytopenic purpura (TTP)</p> Signup and view all the answers

    The main use of Dipyridamole is as a:

    <p>Coronary vasodilator</p> Signup and view all the answers

    What common factor does Glycoprotein IIb/IIIa receptor blockers share?

    <p>They are administered intravenously</p> Signup and view all the answers

    How does Clopidogrel function as an antiplatelet agent?

    <p>It irreversibly inhibits the binding of ADP to its receptors</p> Signup and view all the answers

    Which condition is a contraindication for using Aspirin?

    <p>Anticoagulants</p> Signup and view all the answers

    What is the primary role of thrombolytics in treatment?

    <p>Dissolve existing clots</p> Signup and view all the answers

    Study Notes

    Hemostasis

    • A complex process involving multiple steps and clotting factors
    • Maintains a balance between clot formation and clot breakdown

    Steps in Hemostasis

    • Vascular Phase:
      • Damage to blood vessels initiates vascular spasm (vasoconstriction)
      • Slows or stops blood flow
    • Platelet Phase:
      • Platelets adhere to endothelial cells in larger vessels
      • Platelet aggregation forms a platelet plug
    • Coagulation Phase:
      • Fibrinogen (plasma protein) converts to fibrin (insoluble protein) via thrombin
      • Fibrin forms a network that traps blood cells and platelets, creating a thrombus (clot)
    • Extrinsic Pathway:
      • Initiated by material outside the blood
      • Rapid process
      • Smaller clots
    • Intrinsic Pathway:
      • Initiated by blood's contact with exposed collagen in vessel walls
      • Slower
      • Larger clots
    • Clot Retraction:
      • Begins 2 to 3 days after clot formation
      • Contractile proteins within platelets contract, tightening the clot

    Anticoagulants

    • Warfarin:
      • Coumarin derivative
      • Mechanism of Action (MOA): Inhibits vitamin K synthesis
      • Route: Oral or IV
      • Monitoring: Prothrombin Time - International Normalized Ratio (PT-INR)
      • Target: INR 2-3
    • Heparin:
      • Sulfated glycosaminoglycan
      • MOA: Activates antithrombin III
      • Route: IV or subcutaneous (SC), IM is contraindicated (risk of hematoma)
      • Monitoring: Activated Partial Thromboplastin Time (aPTT)
      • Target: 1.5-2.5x control

    Vitamin K

    • Procoagulant used as an antidote for Warfarin toxicity
    • Signs of Warfarin toxicity: bruising, bleeding gums, nosebleeds, blood in urine or stool
    • Uses: Management of thrombosis associated with Heparin-induced thrombocytopenia
    • Idarucizumab: Humanized monoclonal antibody fragment that binds to dabigatran (direct thrombin inhibitor) and reverses its anticoagulant effect

    Antithrombotic - Antiplatelet Drugs

    • Regulate platelet function
    • Substances developed outside the platelet:
      • Catecholamines
      • Collagen
      • Thrombin
      • Prostacyclin
    • Agents generated internally within the platelet interacting with membrane receptors:
      • ADP
      • Prostaglandin D2
      • Prostaglandin E2
      • Serotonin
    • Agents generated internally within the platelet interacting within the platelet:
      • Prostaglandin endoperoxidases
      • Thromboxane A2
      • cAMP
      • cGMP
      • Ca2+

    Antiplatelet Drugs

    • Prolong bleeding time by interfering with platelet aggregation
    • Subclasses:
      • TXA2 synthesis blocker: Aspirin
      • ADP receptor blockers: Clopidogrel, Ticlopidine, Prasugrel,
      • Glycoprotein IIb/IIIa receptor blockers: Abciximab, Eptifibatide, Tirofiban
      • PDE inhibitors: Dipyridamole

    Aspirin (Acetylsalicylic Acid)

    • MOA: Irreversible inhibition of COX
    • Uses: Prophylactic for transient cerebral ischemia and to reduce the incidence of recurrent MI
    • Adverse effects: Increased hemorrhagic stroke, gastrointestinal bleeding, Salicylism (tinnitus)
    • Contraindication: Anticoagulants (increased bleeding), Ibuprofen (antagonizes platelet inhibition)
    • Dose: 100 to 325 mg

    ADP Receptor Blockers (Thienopyridines)

    • MOA: Irreversibly inhibit the binding of ADP to its receptors on platelets
    • Examples: Clopidogrel, Ticlopidine, Prasugrel, Ticagrelor
    • Preferred agent in ischemic heart disease events: Clopidogrel
    • Ticlopidine causes: Neutropenia/agranulocytosis, Thrombotic Thrombocytopenic Purpura (TTP), Aplastic anemia

    Glycoprotein IIa/IIb Receptor Blockers

    • Drugs: Abciximab, Eptifibatide, Tirofiban
    • Abciximab: Chimeric monoclonal antibody given IV with heparin or ASA for patients undergoing angioplasty
    • Side effects: Bleeding

    Phosphodiesterase Inhibitor

    • Example: Dipyridamole
    • Coronary vasodilator typically given in combination with aspirin or warfarin
    • Ineffective alone
    • Side Effect: Coronary steal phenomenon

    Thrombolytics

    • Used to dissolve existing clots

    Hemophilia

    • Hemophilia A: Factor VIII (FVIII) deficiency or classic hemophilia
    • Hemophilia B: Factor IX (FIX) deficiency or Christmas disease
    • Von Willebrand Disease: Genetic disorder caused by missing or defective von Willebrand factor (VWF)
      • Type 1: 60% to 80% of patients
      • Type 2: 15% to 30% of patients
    • Hemophilia occurs in approximately 1 in 5,000 live births
    • Hemophilia A is four times as common as Hemophilia B
    • More than half of patients with Hemophilia A have the severe form.

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    Drugs for Coagulation and Bleeding PDF

    Description

    Explore the intricate process of hemostasis, including its phases and pathways. This quiz covers vascular, platelet, and coagulation phases, highlighting how clots form and retract. Test your knowledge on the mechanisms that maintain blood balance.

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