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Pulmonary Embolism Thromboembolic Disease

Pulmonary Embolism Thromboembolic Disease. June 2011. Origins of Pulmonary Emboli. Thrombosis in deep veins Predominant sites: femoral to pelvic venous system Clot sheds or breaks off from wall of vessel Travels via the vena cava to right heart to lung. RISK Factors for DVT. STASIS

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Pulmonary Embolism Thromboembolic Disease

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  1. Pulmonary EmbolismThromboembolic Disease June 2011

  2. Origins of Pulmonary Emboli • Thrombosis in deep veins • Predominant sites: femoral to pelvic venous system • Clot sheds or breaks off from wall of vessel • Travels via the vena cava to right heart to lung

  3. RISK Factors for DVT • STASIS • ENDOTHELIAL INJURY • HYPERCOAGULABLE STATE Vast majority of PE originate from DVT in femoral, pelvic and/or iliac deep veins

  4. Clinical scenarios • Bedridden • Post-operative • ORTHOPEDIC PROCEDURES • UNDERLYING MALIGNANCY • Pregnancy • Immobility • (Planes, cars, buses, etc.)

  5. Clinical Features of PE • Tachypnea, Tachycardia • Dyspnea, especially sudden onset • Pleuritic pain • Cough • Signs and symptoms of DVT • Fever, hemoptysis, syncopy • Hypotension, death

  6. Guessing/Gestault No PE PE + 0% -------------50%-------------100% Disease is both overdiagnosed (leading to excess therapy) AND underdiagnosed (leading to morbidity and mortality)

  7. Trying to Make the Diagnosis: • 1845: Virchow’s BIG 3 • 1977: The Emperor Has No Clothes! • 1990: PIOPED: testing algorhythm • 2003: PIOPED II: evaluate CT • Refinement of CTs, D-Dimers! New drugs! • Current: Testing starts based on clinical judgement

  8. Risk Assessment Tools • Wells criteria • Clinical risk assessment score • Canadian score • Charlotte rules

  9. Pretest Probability of PEWells et al. ThrombHaemost. 2000 Clinical signs/symptoms of DVT PE more likely than other diagnosis Heart rate > 100 Immobilization, surgery (past 4 wks) Previous DVT/PE Hemoptysis Malignancy (past 6 months) • 3.0 • 3.0 • 1.5 • 1.5 • 1.0 • 1.0 • 1.0

  10. Scoring • > 6.0 High probability • 2.0 – 6.0 Moderate probability • < 2.0 Low probability

  11. Clinical Predictive ModelWicki et al. ThrombHaemost. 2000 • Age: > 60 1 pt., > 79 2 pts. • Prior DVT/PE 2 pts. • Recent Surgery 3 pts. • HR > 100 1 pt. • PaCO2 < 36 2 pts., 36-39 1 pt. • PaO2 scaled 1 to 4 pts. (4 for < 49) • CXR: atelectasis 1 pt; ↑ diaphr. 1 pt.

  12. Scoring • 0 to 4 : Low risk (10% probability) • 5 to 8 : Moderate (38%) • 9 to 12 : High risk (81%)

  13. Initial Evaluation • CXR • Exclude alternate diagnoses • PE: CXR usually abnormal but nonspecific • ECG: • Primarily to exclude other diagnoses • Troponin: prognostic not diagnostic • ABG • PaO2 < 80 in over 80% of PE patients

  14. Initial Diagnostic Testing • Clinical score moderate to high • Other diagnoses not present • PIOPED suggested VQ scan #1 • Consider d-dimer determination

  15. Value of D-Dimer • Negative excludes DVT and PE • Level < 500 ng/L by ELISA effectively excludes PE for lower risk patients • Rapid assays (whole blood, latex agglutination) less sensitive

  16. Possible Diagnostic Approaches for PE • Pulmonary angiography • Ventilation-perfusion lung scan • Venous ultrasound imaging • Spiral CT Angiography

  17. Angiograms • Intravascular filling defect ** • Can be technically limited • Complications: hypotension, arrhythmias, arterial rupture, dye reaction – all 1% or less incidence

  18. VQ Scans • Negative perfusion scan excludes PE • High probability scan: 85-90% positive predictive value • Low pretest probability of PE: half scans are false positives • Most scans are non-diagnostic

  19. Venous ultrasound imaging • Positive in 46% with high pretest probability of PE • Positive in 15% with signs and symptoms of DVT at risk for PE • May exclude other diagnosis (Baker’s cyst) • Serial scans cost-ineffective

  20. Spiral CT Angiography • Pioped II: (-) predictive value unclear • Radiology literature: (-) CT excludes “clinically significant” PE • Improvements since PIOPED II: • Multidetector scanners • Slice thickness ↓ from 3 to 1 mm • Increased table speed

  21. Positives • High sensitivity (72%) and specificity (95%) overall • Central emboli: 94%/94% • Positive = Treat • Good for central, segmental, subsegmental • 2 studies suggest it is cost effective

  22. Negatives • Poor for small subsegmental emboli (6 to 36% of all PE) • Requires cooperation and a 15-25 sec. breath hold • More radiation exposure than V/Q scan • Requires IV contrast

  23. Consensus?? • Radiology literature strongly support CT • Sensitive for larger emboli • Need more controlled studies with “gold standard” • Trend to replacing VQ scanning

  24. Diagnostic Protocol • Clinical risk score • D-dimer • VQ or CT • Ultrasound leg study • Consider angiography

  25. Therapy for Pulmonary Embolism and Venous Thrombosis

  26. Therapeutic Options • Anticoagulation • Heparin and derivatives • Vitamin K antagonists • Thrombin inhibitors • Watch out • IVC Filter • Surgical Embolectomy

  27. Unfractionated Heparin • Mix of branched glycosaminoglycans • Administered IV • 1/3 of dose binds Antithrombin • Inactivates thrombin and other factors • 2/3: Minimal anticoagulant effect • Binds endothelial cells, PF4, platelets

  28. UFH • Unpredictable pharmacokinetics • aPTT to 1.5-2.5 X normal • Reversible with protamine sulfate • OK in renal failure • Heparin resistance: • monitor anti-Factor Xa

  29. UFH Complications • BLEEDING • Antithrombin • ↑ vessel wall permiability • Interacts with platelets • Osteopenia • Suppresses osteoblast formation • Activates osteoclasts

  30. HIT • Antibody mediated • Heparin binds to PF4  epitope  Ab binding • Recognition: • Platelets ↓ > 50% • Skin lesions at heparin site’ • Acute systemic reactions

  31. Management of HIT • Monitor platelet count at least QOD for 14 days • If acute systemic rxn: immediate platelet count • Consider venous ultrasonography • Non-heparin anticoagulants

  32. Low Molecular Weight Heparin • Depolymerization of UFH • More anti-Xa than anti-thrombin activity • More favorable benefit/risk ratio • More predictable dose response ratio • Weight based dosing

  33. Monitoring LMWH • Fixed dosing without routine monitoring • Special situations: • Obesity (>150 kg) • Renal Failure: not recommended if Creatinine clearance < 25 • Monitor anti-Factor Xa • Reversal: protamine binds less well to smaller fragments

  34. Fondaparinux • Synthetic analog of heparin pentasaccharide • Equal to UFH, LMWH for thrombosis • No platelet interactions • Once daily dosing • Cautions: renal failure; no readily available reversing agent

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