Venous Thromboembolism Prophylaxis

Venous Thromboembolism Prophylaxis - Clot Patrol Kickoff

• VTE: Deep Vein Thrombosis (DVT) & Pulmonary Embolism (PE). Prevention is key.
• Pathogenesis: Virchow's Triad (📌 SHE):
  • Stasis (e.g., immobility, paralysis)
  • Hypercoagulability (e.g., malignancy, thrombophilia, OCPs)
  • Endothelial injury (e.g., surgery, trauma, central lines)
• Major Risk Factors:
  • Surgery (orthopedic, major general, neurosurgery)
  • Trauma (major, spinal cord injury)
  • Immobility (bed rest >3 days)
  • Active cancer
  • Prior VTE
  • Age >40 (risk ↑ with age)
  • Obesity (BMI >30 kg/m²)

⭐ VTE is a leading cause of preventable hospital deaths worldwide, making prophylaxis critical in at-risk patients an exam favourite topic for scenarios on post-operative complications or immobile medical patients.

Venous Thromboembolism Prophylaxis - Risk Radar On

• VTE risk stratification is crucial for appropriate prophylaxis.
• Surgical Patients: Utilize the Caprini Score.
  • Assesses individual risk factors to guide LMWH, UFH, or mechanical prophylaxis.
• Medical Patients: Employ the Padua Prediction Score.
  • Identifies high-risk hospitalized medical patients needing pharmacologic prophylaxis.

⭐ The Padua Prediction Score of ≥4 indicates high risk for VTE in medical patients, warranting pharmacologic prophylaxis unless contraindicated.

• Low risk: Early ambulation.
• Moderate/High risk: Pharmacological (LMWH, UFH) +/- mechanical methods (IPC).

Venous Thromboembolism Prophylaxis - Drug Power-Plays

• Unfractionated Heparin (UFH)
  • Dose: 5000 IU SC q8-12h.
  • Reversal: Protamine sulfate.
  • ⚠️ Key risks: HIT, bleeding.
• Low Molecular Weight Heparin (LMWH) (e.g., Enoxaparin)
  • Dose: Enoxaparin 40mg SC OD (standard); 30mg SC BD (high-risk ortho).
  • Reversal: Protamine sulfate (partial).
  • ⚠️ Adjust for CrCl <30 mL/min; lower HIT risk vs UFH.
• Direct Oral Anticoagulants (DOACs) (e.g., Rivaroxaban, Apixaban)
  • Dose: Rivaroxaban 10mg OD (post-op ortho).
  • Reversal: Specific agents (Andexanet alfa, Idarucizumab).
  • ⚠️ Drug interactions; caution in renal/hepatic impairment.
• Fondaparinux (Synthetic pentasaccharide)
  • Dose: 2.5mg SC OD.
  • No specific reversal agent.
  • ⚠️ Contra: CrCl <30 mL/min, body weight <50kg.

⭐ LMWH is generally preferred over UFH for perioperative VTE prophylaxis due to predictable pharmacokinetics and lower HIT risk.

Venous Thromboembolism Prophylaxis - Squeeze & Prevent

Non-pharmacological methods are crucial, especially with high bleeding risk or when anticoagulants are contraindicated.

• Mechanical Prophylaxis:
  • Graduated Compression Stockings (GCS): Apply 18-21 mmHg at the ankle, decreasing proximally.
  • Intermittent Pneumatic Compression (IPC) devices: Sequentially inflate and deflate sleeves, mimicking the calf muscle pump to enhance venous return.
  • Venous Foot Pumps (VFP): For immobile patients.
• Early Ambulation: Encourage as soon as feasible post-operatively.

⭐ IPC devices are generally more effective than GCS alone for VTE prevention in moderate to high-risk surgical patients, especially if pharmacologic prophylaxis is contraindicated due to bleeding risk.

Venous Thromboembolism Prophylaxis - OR Clot Blockers

• Pharmacological Timing:
  • LMWH: Start 12h pre-op or 6-12h post-op. Hold 24h pre-procedure.
  • UFH: Start 2h pre-op or 4-6h post-op. Hold 4-6h pre-procedure.
• Bridging (Warfarin): Stop 5 days pre-op. Bridge if INR < 2.0 or high VTE risk. Resume post-op, overlap till INR therapeutic.
• Mechanical: IPC/GCS for high bleeding risk or as adjunct.
• Duration: Until mobile; extended (up to 28-35 days) for high-risk (e.g., major ortho, cancer).

⭐ DOACs: Stop 24-96h pre-op based on drug, renal function, & bleed risk. E.g., Dabigatran (renal clearance) often needs longer hold vs. Apixaban/Rivaroxaban.

High‑Yield Points - ⚡ Biggest Takeaways

• Risk stratification (e.g., Caprini score) is crucial to determine VTE prophylaxis.
• Early ambulation is a key non-pharmacological measure for all patients.
• LMWH is generally preferred over UFH for surgical prophylaxis.
• Extended prophylaxis (up to 28-35 days) for high-risk surgeries (e.g., major cancer, hip/knee arthroplasty).
• Mechanical prophylaxis (IPC devices) is essential for patients with high bleeding risk.
• Aspirin alone is inadequate for VTE prevention in moderate-high risk surgical patients.