Overview
This lecture covers deep vein thrombosis (DVT), including its definition, risk factors, signs and symptoms, prevention, diagnosis, and nursing management.
DVT Basics & Pathophysiology
- Deep vein thrombosis (DVT) is a blood clot forming in a deep vein, mostly in the legs, pelvis, or hip.
- DVT is a type of venous thromboembolism (VTE); another type is pulmonary embolism (PE).
- Clots in deep veins can travel to the heart and lungs, causing a potentially fatal pulmonary embolism.
- Most DVTs occur in lower extremity veins such as perineal, posterior tibial, popliteal, and superficial femoral veins.
Virchow’s Triad: DVT Risk Factors
- Three main factors increase DVT risk: venous stasis, hypercoagulability, and endothelial damage ("SHE").
- Venous stasis occurs due to immobility, varicose veins, surgery, long travel, pregnancy, obesity, heart failure, and atrial fibrillation.
- Hypercoagulability results from cancer, sepsis, dehydration, estrogen use (birth control), heparin-induced thrombocytopenia, and postpartum state.
- Endothelial damage includes trauma, IV drug use, venipuncture, indwelling devices (IV line, catheter), irritating medications, or surgery.
Signs & Symptoms of DVT
- Signs include redness, swelling, warmth, and unilateral leg changes near clot site.
- Compare both legs; affected leg is swollen, red, and warm.
- Positive Homan’s sign: pain with dorsiflexion, but not a reliable indicator.
Diagnosis
- Ultrasound is used to confirm the presence of a blood clot.
- D-dimer blood test detects fibrin degradation fragments, indicating clot breakdown.
- Positive D-dimer suggests possibly a clot but is not specific and may be falsely positive in other diseases.
- Labs: D-dimer negative if FEU <500 ng/mL or DDU <250 ng/mL.
Prevention in At-Risk Patients
- Use sequential compression devices (SCDs) to promote blood flow, unless DVT is present in the extremity.
- Encourage ambulation and leg exercises; apply compression stockings as ordered.
- Administer prophylactic anticoagulants (e.g., enoxaparin) and monitor for bleeding risks.
Nursing Management for Active DVT
- Remember "DEEP CLot" for nursing interventions:
- D: Don’t massage/rub the area.
- E: Elevate limb above heart level.
- E: Ensure initial bed rest.
- P: Pharmacological management (anticoagulants, thrombolytics, IVC filter).
- Heparin (indirect thrombin inhibitor): fast acting, IV/SubQ, weight-based, monitor aPTT (therapeutic = 1.5-2.5x normal).
- Protamine sulfate is the antidote for heparin.
- Warfarin (vitamin K antagonist): slow onset, oral, monitor INR (therapeutic = 2-3), antidote is vitamin K.
- Thrombolytics (e.g., tPA) break up clots but carry high bleeding risk.
- IVC filter prevents clots from reaching the heart/lungs if anticoagulants cannot be used.
- Apply warm, moist compresses and monitor leg circumference for swelling.
- Observe for PE symptoms: sudden dyspnea, low O2, tachycardia, chest pain, anxiety, sweating.
- Use tight compression stockings as ordered to reduce swelling and prevent post-thrombotic syndrome.
Key Terms & Definitions
- DVT (Deep Vein Thrombosis) — Clot in a deep vein, usually in the lower extremities.
- VTE (Venous Thromboembolism) — Includes DVT and pulmonary embolism.
- Virchow’s Triad — Three risk factors for thrombosis: stasis, hypercoagulability, endothelial damage.
- D-dimer — Lab test for fibrin degradation products, indicating clot breakdown.
- Heparin — Fast-acting anticoagulant, monitored by aPTT, antidote is protamine sulfate.
- Warfarin — Oral anticoagulant, monitored by INR, antidote is vitamin K.
- SCD (Sequential Compression Device) — Device to improve venous return and prevent clots.
Action Items / Next Steps
- Take the associated quiz to test your knowledge on DVT.
- Review nursing protocols for DVT prevention and management.
- Study normal and therapeutic lab values for aPTT and INR.
- Practice patient teaching on DVT risk factors and prevention strategies.