Warfarin: Key Concepts for Nursing Exams

Introduction to Warfarin

• Warfarin is a common anticoagulant, often referred to as a "blood thinner."
• Used to prevent blood clots in patients with a history of:
  • Deep vein thrombosis (DVT)
  • Pulmonary embolism
  • Heart attacks
  • Strokes

Mechanism of Action

• Warfarin works by thinning the blood to prevent clot formation.

Side Effects

• Major side effect: Bleeding
  • Be aware of signs of uncontrolled bleeding:
    • Severe bruising
    • Tarry stools
    • Sudden drop in blood pressure

Monitoring and Lab Values

• PT (Prothrombin Time):
  • Laboratory measure of blood clotting time
  • Desired PT is 2 to 3 times the patient's baseline
• INR (International Normalized Ratio):
  • Derived from PT
  • Target INR for therapeutic effect: 2 to 3
  • Below 2: Risk of clots
  • Above 3: Risk of severe bleeding

Teratogenic Effects

• Warfarin is teratogenic ("teratogenic tarantula" mnemonic)
  • Contraindicated in pregnancy
  • Alternative anticoagulants recommended for pregnant patients

Dietary Considerations

• Avoid high intake of leafy greens (e.g., kale)
  • Leafy greens are high in Vitamin K, which reverses Warfarin effects

Reversal of Warfarin Effects

• Vitamin K is the antidote:
  • Administered via intramuscular injection or IV to reverse effects in cases of overdose or pre-surgery.

Summary

• Warfarin: used to prevent blood clots, requiring careful monitoring of PT and INR.
• Side effects include bleeding, teratogenic risk, and interaction with Vitamin K-rich foods.
• Effective INR range for patients: 2 to 3.
• Avoid use during pregnancy and monitor diet for Vitamin K intake.

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