Thromboembolic complications

Virchow's Triad - The Clotting Trifecta

Three primary abnormalities in blood composition, flow, and vessel wall that predispose to thrombosis. 📌 Mnemonic: SHE

• Stasis: Reduced blood flow.
  • Immobilization (post-op, paralysis, long travel).
  • Cardiac dysfunction (atrial fibrillation, heart failure).
• Hypercoagulability: Increased tendency to clot.
  • Inherited: Factor V Leiden, prothrombin gene mutation.
  • Acquired: Malignancy, pregnancy, OCPs, sepsis.
• Endothelial Injury: Damage to the vessel lining.
  • Trauma, surgery, IV catheters, atherosclerosis.

⭐ Factor V Leiden is the most common inherited thrombophilia, causing resistance to activated protein C.

DVT Diagnosis & Management - Deep Trouble Leg Day

• Diagnosis:
  • Wells Score: Stratifies pre-test probability. >2 = DVT likely.
  • First-line Imaging: Compression ultrasonography with Doppler. Shows non-compressible vein.
  • D-Dimer: High negative predictive value. Used to rule out DVT in low-probability patients (Wells score <2).

• Management:
  • Anticoagulation: LMWH or DOACs (e.g., apixaban, rivaroxaban) for at least 3 months.
  • IVC Filter: For patients with contraindications to anticoagulation (e.g., active bleeding).

⭐ Phlegmasia Cerulea Dolens: A rare, limb-threatening complication of massive DVT causing venous outflow obstruction, intense pain, cyanosis, and edema.

Pulmonary Embolism - Lethal Lung Lodger

• Pathophysiology: Occlusion of pulmonary arteries, most commonly from a dislodged deep vein thrombus (DVT).

• Presentation: Sudden-onset dyspnea, pleuritic chest pain, tachypnea, and tachycardia. Hemoptysis can occur.

  • 📌 Virchow's Triad (risk factors): Stasis, Hypercoagulability, Endothelial injury.

• Diagnosis:

  • Best initial test: CT Pulmonary Angiography (CTPA) is the gold standard.
  • V/Q Scan: Used if CTPA is contraindicated (e.g., renal failure, contrast allergy).
  • D-dimer: High negative predictive value; useful to rule out PE in low-risk patients.

⭐ Physiological Dead Space: In PE, ventilated lung segments are not perfused, leading to a profound ventilation/perfusion (V/Q) mismatch. This is the primary cause of hypoxemia.

• Management:
  • Anticoagulation: Immediate start with Heparin or LMWH, bridged to Warfarin or a DOAC.
  • Thrombolysis: For massive PE with hemodynamic instability.

VTE Prophylaxis - Clot Blockers United

• Risk Stratification: Use the Caprini score to guide therapy intensity for surgical patients.
• Mechanical Methods: Primarily for patients at high risk of bleeding.
  • Intermittent Pneumatic Compression (IPCs).
  • Graduated Compression Stockings (GCS).
• Pharmacological Agents: The mainstay for moderate-to-high risk patients.
  • LMWH: Enoxaparin 40mg SC daily.
  • UFH: 5000 units SC q8-12h.
  • Fondaparinux: Use if history of HIT.
• Early Ambulation: A crucial baseline intervention for all postoperative patients.

⭐ Pharmacologic prophylaxis is contraindicated in patients with active bleeding, severe bleeding diathesis, or a platelet count < 50,000/μL.

📌 VTE Prevention: Very Early ambulation, Thrombotics, External compression.

• Virchow's triad (stasis, hypercoagulability, endothelial injury) is the cornerstone of pathophysiology.
• Pulmonary embolism (PE) is the most common preventable cause of death in hospitalized patients.
• Major risk factors include orthopedic/pelvic surgery, malignancy, and prolonged immobility.
• Prophylaxis is key: early ambulation, pneumatic compression, and pharmacologic agents (LMWH).
• Diagnose DVT with duplex ultrasound; diagnose PE with CT angiography.
• Treatment involves systemic anticoagulation; consider an IVC filter if contraindicated.