Anticoagulants

• Circulatory Disorders

  • Anticoagulants & antiplatelets
  • Thrombolytics
• Anticoagulants


  Prevent formation of clots that inhibit circulation
• Antiplatelets


  Prevent platelet aggregation
• Thrombolytics


  Dissolve formed clots
• A thrombus is a clot formed in an arterial or venous vessel
• Thrombophlebitis


  Both inflammation and clots are present
• Some thrombus can be superficial but it’s the DVT that’s a concern
• DVT occurs

  Embolism to lungs
• Arterial thrombus formation

  1. Platelet adhesion

  2. ADP released

  3. More platelet aggregation

  4. Blood flow inhibited

  5. Fibrin, platelets & RBC’s surround clot

  6. Build up of size structure

  7. Occludes blood vessels

  8. Tissue ischemia
• The result of Arterial Thrombus is localized tissue injury from lack of perfusion
• Venous thrombus formation


  1. Slow blood flow

  2. Stagnation initiates coagulation cascade

  3. Production of fibrin

  4. Enmeshes RBC’s & platelets

  5. Forms thrombus
• Venous thrombus has a long tail that can break off to produce an embolus
• Embolus travels to faraway sites


  Lodges in lung (capillary level)
• Inadequate O2 & CO2 exchange occurs (ie. pulmonary embolism & cerebral embolism)
• Hemostasis


  The normal homeostatic process of blood clotting
• Clotting proteins normally circulate in an inactive state & must be activated to form a fibrin clot
• Intrinsic clotting path


  1. Blood vessel injured

  2. Platelets adhering to site

  3. Release of ADP

  4. Platelet plug forms
• Extrinsic pathway activation

  Tissue injury (outside blood vessels)
• Risk factors for Deep Vein Thrombophlebitis and Thromboembolism

  • Stasis of venous flow
  • Damage of the endothelium
  • Hypercoagulability of the blood
• Additional risk factors


  • History of thrombophlebitis
  • Abdominal & pelvic surgery
  • Obesity
  • Neoplasms (lung)
  • CHF
  • Advanced age
  • Vasospasm
  • Prolonged immobility
  • CVA
  • MI
  • PG
  • Post partum
  • Estrogen TX
  • Trauma
  • Sepsis
  • Hypercoagulable states
• Anticoagulants


  Inhibit clot formation but do NOT dissolve clots already formed
• Anticoagulants are used in clients with venous and arterial disorders that put them at increased risk of clot formation
• Venous disorders


  • DVT
  • Pulmonary embolism
• Arterial disorders


  • Coronary thrombosis (MI)
  • Artificial heart valves
  • CVA
• Heparin


  A natural substance in the liver that prevents clot formation
• The primary use of heparin is to prevent venous thrombosis that can lead to pulmonary embolism (PE) or stroke
• Heparin action

  1. Combines with antithrombin III

  2. Inactivates thrombin and other clotting factors

  3. Prevents conversion of fibrinogen to fibrin
• Heparin is poorly absorbed through GI mucosa and is given SQ & IV
• Heparin prolongs clotting time, monitored by PTT & aPTT
• Heparin uses


  • DVT
  • PE
  • CVA
  • Clients with heart valve prosthesis
  • During CV surgery
  • Post operative
  • During hemodialysis
• Low doses of heparin are used prophylactically to prevent DVT
• Full doses of heparin treat a thromboembolism and promote neutralization of activated clotting factors
• If started shortly after formation of a thrombus, heparin will prevent it from developing into an insoluble stable thrombus
• Heparin reduces tissue damage
• Heparin side effects

  Decreased platelet count (thrombocytopenia)<|>Hemorrhage
• Protamine sulfate IV is given as an anticoagulant antagonist for heparin overdose
• Heparin drug interactions

  • Increased effects with ASA
  • NSAIDs
  • Thrombolytics
  • Decreased effect with NTG
• Low Molecular Weight Heparins (LMWHs)

  Recently introduced to prevent venous thromboembolism
• LMWHs bind to Antithrombin III which inhibits the synthesis of factor Xa & formation of thrombin
• Examples of LMWHs

  • Enoxaparin
  • Dalteparin