Deep Vein Thrombosis (DVT)

• Deep vein thrombosis (DVT) and pulmonary embolus (PE) are related conditions that can be treated with coagulation modifier drugs.

Deep Vein Thrombosis (DVT)

• Formation of a thrombus, blood clot, connected to vein inflammation.
• Superficial vein thrombosis involves a thrombus in a superficial vein, usually in the extremities.
• DVT involves a thrombus in a deep vein, typically in the iliac or femoral veins.
• Venous thromboembolism is when a DVT detaches and travels to the pulmonary artery, causing a pulmonary embolus.

Etiology of DVT - Virchow's Triad

• Venous stasis occurs when:
  • Valves are dysfunctional.
  • Muscles in extremities are inactive.
  • Obesity, pregnancy, post-operative state, and immobility.
• Damage to the endothelium can be: Direct: fracture, surgery, or trauma. Indirect: chemotherapy or diabetes.
• Hypercoagulability of the blood can be due to hematologic disorders, anemias, malignancies, or clotting/protein deficiencies.

Risk Factors for DVT

• Pregnancy.
• Oral contraceptives.
• Post-menopausal therapy.
• Hormone replacement therapy.
• Post-chemotherapy or hysterectomy.

Pathophysiology of DVT

• Platelet aggregation and fibrin entrap RBCs, WBCs, and platelets, leading to thrombus formation.
• As the thrombus enlarges, more cells adhere.
• If the thrombus detaches, it becomes an embolus.
• Emboli can lead to a pulmonary embolus, so called because it enters the pulmonary system.

DVT: Clinical Manifestations

• Unilateral leg edema.
• Extremity pain.
• Fullness in calf/thigh.
• Erythema and warmth.
• Positive Homan's sign: pain with dorsiflexion of the foot.

DVT: Complications

• Pulmonary Embolus:
  • Blockage of the pulmonary arteries by thrombus.
  • Mobile clots that travel.
  • 30% mortality.
  • Can be caused by atrial fibrillation or upper extremity DVT.

PE: Clinical Manifestations

• Dyspnea
• Chest pain
• Hemoptysis
• Cough
• Pleuritic chest pain
• Crackles on auscultation of lungs

Hemostasis and Coagulation

• Hemostasis is any process that stops bleeding.
• Coagulation is hemostasis through physiological blood clotting.
• A complex relationship occurs between substances that promote clot formation and those that inhibit coagulation or dissolve clots.
• Coagulation System:
  • Described as a "cascade."
  • Activated factors serve as a catalyst to amplify reactions.
  • The result is fibrin, a clot-forming substance.
  • Involves intrinsic and extrinsic pathways.

Coagulation Modifier Drugs

• Anticoagulants (oral and parenteral).
  • Inhibit the action or formation of clotting factors.
  • Prevent clot formation.
• Antiplatelet drugs:
  • Interfere with platelet function.
  • Inhibit platelet aggregation.
  • Prevent platelet plugs.
• Thrombolytic/Fibrinolytic drugs:
  • Lyse (break down) existing clots.
• Direct Thrombin inhibitors
• Direct Inhibitors of Factor XA

Parenteral Anticoagulants (Heparin)

• Mechanism of Action: activates antithrombin to prevent clotting, inhibits thrombin.
• Used prophylactically to prevent clot formation.
• Used for embolus.
• Utilized in emergency conditions requiring prompt therapy, stroke, DVT and PE
• Adverse reactions: hemorrhage, heparin-induced thrombocytopenia, hypersensitivity reactions, and toxicity.
• Routes of administration: SQ/IV infusion.

Parenteral Anticoagulants: Nursing Administration of Heparin

• Intravenous Heparin:
  • Obtain Baseline vitals.
  • Obtain Baseline labs: CBC, PLT, HCT.
  • Obtain APTT (Activated Partial Thromboplastin Time) every 4-6 hours until stable. -Therapeutic APTT = 1.5-2.5X normal as a indicator.
  • Verify different concentrations of label.
  • Double-check dose with a second nurse.
  • Administered via an infusion pump.
  • Antidote: Protamine Sulfate.
• Subcutaneous Heparin:
  • Use a 25-28 gauge needle (1/2-5/8 inches).
  • Inject in the abdomen at least 2 inches away from the umbilicus.
  • Do not aspirate.
  • Apply gentle pressure to the injection site for 1-2 minutes.
  • Rotate sites.

Parenteral Anticoagulants: enoxaparin (Lovenox)

LMWH (Low Molecular Weight Heparin)

• Mechanism of Action: Acts primarily on coagulation factor Xa, limiting the generation of thrombin needed for the production of fibrin.
• Uses: Prevent DVT in post-op patients and certain types of MI, and to treat DVT/PE.
• Route of Administration: SQ only.
• Adverse Effects: Hemorrhage, neurologic damage from hematoma formation from spinal/epidural anesthesia, and thrombocytopenia.
• Nursing Administration: Most syringes are pre-filled.
  • Do not expel air bubble.
  • Inject in the abdomen without aspiration.
  • Rotate injection sites.
  • Monitor for bleeding.
• Antidote: Protamine Sulfate.

Oral Anticoagulants: warfarin sodium (Coumadin)

• Mechanism of Action: Antagonizes Vitamin K, preventing the synthesis of additional coagulation factors.
• Uses: Treatment of DVT, prevention of clots in AFIB and with prosthetic valves, and prevention of Transient Ischemic Attacks (TIA), PE, and DVT.
• Route of Administration: Oral.
• Monitored by prothrombin time (PT) and international normalized ratio (INR).
• Antidote: Vitamin K.
• Long-term outpatient therapy with variable dosage.
• Example:
  • Mon, Wed, Fri, Sun 5mg PO daily.
  • Tues, Thurs, Sat daily = 2.5mg PO daily.

Warfarin Sodium: Nursing Implications

• Should be started while the patient is still being administered heparin until PT-INR levels indicate adequate anticoagulation.
• There should be follow up appointments.
• Monitor PT-INR regularly.
• The therapeutic PT-INR = 2-3x's normal value.
• Many herbal products have potential interactions—increased bleeding may occur from:
  • Capsicum pepper
  • Garlic
  • Ginger
  • Ginkgo
  • St. John's wort
  • Feverfew

Direct Thrombin Inhibitors: dabigatran (Pradaxa)

• Mechanism of Action: Directly inhibit thrombin, preventing thrombus development.
• Uses: Prevent stroke or embolism in patients with afib not caused by valvular heart disease.
• Route of Administration: Orally only (should not be crushed).
  • Can take with or without food.
  • Discontinue other anticoagulants when starting dabigatran.
• Adverse effects: Bleeding and GI discomfort.

Direct Inhibitor of Factor XA (rivaroxaban (Xarelto)

• Mechanism of Action: Anticoagulation by inhibiting Factor Xa.
• Uses: Prevents DVT and PE in clients undergoing total hip or knee/arthroplasty.
• Route of Administration: Administer tablets orally once a day with or without food at the same time every day.
• Monitor Hgb, HCT, and liver and kidney function during treatment.
• Adverse effects: Bleeding and elevated liver enzymes.

Anticoagulants: Patient Education

• Regular lab testing should be performed.
• Be aware of the signs of abnormal bleeding.
• Measures needed to prevent bruising, bleeding, or tissue injury.
• Wearing a medical alert bracelet,
• Avoiding foods high in vitamin K (tomatoes, dark leafy green vegetables).
• Consultation with a physician before taking other medications or over-the-counter products, including herbals, is needed.

Antiplatelet Drugs

• Prevent platelet adhesion, resulting in:
  • Reduced risk of fatal and nonfatal strokes.
  • Helpful for acute unstable angina and MI.
• Adverse effects: Bleeding.
• Common Antiplatelet Drugs:
  • Aspirin: cardio-protective, PO and suppository, available in 81mg or 325mg dosages.
  • clopidogrel (Plavix): for patients with stents, available in 75mg PO daily dose.
  • eptifibatide (Integrilin) (IV):
    • Antiplatelet/glycoprotein inhibitor.
    • Administered in ICU or Cardiac Cath lab.
    • Adverse effects: Bleeding, hypotension and bradycardia.

Thrombolytic Drugs/Fibrinolytics

• Drugs that break down/lyse pre-formed clots.
• A.K.A "Clot busters".
• Indications:
  • Conditions like DVT and pulmonary embolus.
  • Occlusion of shunts or catheters.
  • Treatment of acute MI (initiation MUST be within 6 hours of onset of symptoms).
  • Treatment of acute ischemic stroke (initiation MUST be within 3 hours of onset of symptoms).
• Examples:
  • anistreplase (Eminase)
  • alteplase (t-PA, Activase)
  • reteplase (Retavase)
  • tenecteplase (TNKase)

Thrombolytic Drugs/Fibrinolytics:

Mechanism of Action

• Activate the fibrinolytic system for quick breakdown of the clot.
• Activate plasminogen and convert it to plasmin, which can digest fibrin.
• Reestablish blood flow to areas of the body:
  • The lungs via the pulmonary artery.
  • The heart muscle via coronary arteries (prevents tissue destruction).
• Adverse Effects:
  • Bleeding (Internal, Intracranial—altered level of consciousness., Superficial).
  • Other effects: Nausea and vomiting, Hypotension, Anaphylactic reactions, Cardiac dysrhythmias.

Thrombolytic Drugs:

Nursing Implications

• Always follow the preparation and administration guidelines.
• Monitor IV sites for redness, pain, and bleeding.
• Monitor for bleeding from the gums, nose, mucous membranes or injection sites.
• Be aware of internal bleeding.
• Monitor patient for changes in mental status.

Coagulation Modifier Drugs:

Nursing Implications

• Monitor for therapeutic effects.
• Monitor for signs of excessive bleeding, such as:
  • Bleeding of gums while brushing teeth.
  • Unexplained nosebleeds.
  • Heavier menstrual bleeding.
  • Bloody or dark, tarry stools.
  • Bloody urine or sputum.
  • Abdominal pain.
  • Vomiting blood.