DVT and PE

1. DVT and PE Pathophysiology, prophylaxis, treatmentAnton Sharapov

2. Cases to consider • 38 yom for elective IHR • 65 yom for elective IHR • 65 yom, obesity/CHF/prev DVT for IHR • 25 yof post severe head injury • 25 yom post trauma/abdo/chest • 75 yof post hip # • 65 yom post THA, obese

3. Scope of the problem • Common postop complication • Asymptomatic > symptomatic • Difficult to study • Most studies evaluate asymptomatic pts

4. Epidemiology • VTE 48:100,000 • PE 69:100,000 • Incidence – 20-70% surgery pts • ½ begin in OR

5. Epidemiology • DVT and PE – different stages of same disease process • 10% proximal DVTs progress to symptomatic PE • 25% distal DVTs become proximal

6. Outcomes • Most asymptomatic VTE recover sans treatment and complications • Less then 1 in 8 confirmed clots progress to symptomatic thromboembolic disease • Important to observe clots over a period of time

7. Outcomes of PE • Outcomes of PE are difficult to assess • Registry estimates are always higher then in clinical studies (7% vs 2%) • Mortality is a function of RV function, clot burden, and comorbidities • Risk of fatal PE greatest 3-7 postop • Asymptomatic PE are common • 40% of asymptomatic prox DVTs

8. Assessment • Assess risk of DVT and risk of bleeding • Assess duration of prophylaxis • Assess Virchov triad • Venous stasis • Endothelial injury • hypercoagulability

9. Risk factors: venous stasis • Immobility & tourniquet application • Institutionalization • CVA • Paralysis • CHF • Travel >4 hours • Obesity • Respiratory failure • Varicose veins • Duration/extent of postop immobilization

10. Risk factors: endothelial injury • Trauma • Atherosclerosis • Perioperative • Malignancy • Post-phlebitic syndrome • Prior DVT • CV catheter • Inflamatory condition • Hyperhomocysteinemia

11. Risk factors: hypercoagulability, Acquired • Post op • Malignancy • Hormone replacement • Estrogen therapy

12. Risk factors: hypercoagulability, Acquired: • Antiphospholipid antibody • Lupus anticoagulant – 5-10 fold risk • Myeloproliferative d/o • Paroxysmal nocturnal hemoglobinuria • Nephrotic syndrome • Pn loosing enteropathy

13. Risk factors: hypercoagulability, Inherited: • Factor V leiden – APC resistance • Absolute risk post op VTE is small - 1/100 • Relative risk increased (3-5 fold) • Screening not recommended • Antithrombin, pn C/S deficiency • Fibrinogen/TPA defects • Prothrombin gene mutation

14. Risk factors: Miscelaneous • Use/nonuse of thrombopophylactic measures • Age - rises linearly after 40 • Ethnicity: • Asian/South Pacific - threefold lower • African American - slightly higher • Latin - slightly lower • Site/extent traumatic injury • Knee/spine=major trauma>hip>uro/gyny> neuro>general/thoracic

15. Risk of DVT, miscellaneous • Surgical procedure - most important • Neurosurgery & ortho - 6% & 3% • Major vascular • Bowel, bladder, gastric bypass and kidney transplant • Radical neck, IHR, lap chole (0.3%),TURP, thyroid/parathyroid - lowest risk

16. Need for global integrative assessment • American College of Chest Physicians • Risk stratification tool • Problems: • What defines major vs minor surgeries? • No weighting of Risk Factors • Why age 40 and 60 important?

18. Risk of bleeding • Bleeding d/o • Use of antiplatelet meds • Previous GI bleed • Cancer • Hepatic/renal insufficiency • ?age

19. VTE prophylaxis: what’s available? • Intermittent compression devise • Stockings • ASA 80-325 mg • UF heparin 5000 bid, tid • LMW bid • Warfarin • Anti – Xa pentasaccharide (fondaparinix)

20. Efficacy of mechanical VTE prophylaxis

21. Early ambulation • Routine for all pts • Acceptable as sole mode for low risk • Useful adjunct esp post knee/hip surgery

22. Elastic stockings • First shown to work in 1952 • Decrease venous pooling • Evidence of benefit for mod/high risk, but used only as adjunct • Harmful if not work correctly

23. ICD • Work very well • Not useful form BMI >25 • Only effective if used correctly and continuously when pt not ambulating • Have potential to reduce ambulation • Recommended in mod-high risk gyn surgery as solo • Not recommended as sole mode in • Highest risk – except neurosurgery • High risk urological • Hip and knee surgery

24. IVC • For absolute contraindication of anticoagulation • For life-threatening hem on AC • For failure of AC • Used to prevent fatal PE • Temporary filters preferred • If left in place, cause DVTs

25. Efficacy of pharmacological VTE prophylaxis

26. Aspirin • Not recommended as sole prophylaxis • Beneficial post hip-fracture • 160 mg OD, 5/52, 13,000 pts • Combined with routine prophylaxis • PE – 0.7 vs 1.2 • Fatal PE 18 vs 43

27. UF heparin • Good for moderate risk gen surgery • Modest increase in bleeding • Compared to LMWH (2.65% vs 1.8%) • Additive effect of stockings and ICD] • Risk of HIT

28. warfarin • For very high risk with lower extremity orthopedic and neuro surgery • For gen surgery other methods work just as well… • Good for extended prophylaxis • Delayed onset of action, may start preop! • Recommended for • Hip #, THA, TKA

29. LMW heparin and Pentasaccharideds • Preferential inhibition of factor Xa • FDA approved for DVT prophylaxis • Not FDA approved as of yet for DVT prophylaxis in pregnancy, spinal cord injury, trauma, neurosurgery… but are being used

30. LMW heparin and Pentasaccharideds cont’d • Effective for mod risk general surgery • Gyn/obs • second line to mechanical • Trauma • Method of choice only if risk of bleeding is not significant. If it is – stocking+/-ICD • Recommended for ortho lower extremity surgery • Fondoparinix reduces asymptomatic DVTs only…

31. LMW heparin and Pentasaccharideds cont’d • Risk of epidural hematoma • Strategies • Avoid regional anesth in those prone to bleed • Needle in 12 h after onset of LMWH • Single dose anesthetic better then infusion • D/c cath in 12 h • No dosing of LMWH within 2 h of cath d/c

32. Direct thrombin inhibitors • Effective in initial studies • Comparable to LMWH • For HIT pts

33. Duration of prophylaxis • Start immediately after or prior to surgery • 7-10 days post • Warfarin may be started 10/7 prior but INR should be less then 1.5 • Argument for prolonged (30 day) prophylaxis for high risk. DVT incidence • sympt – 3% vs 1% on treatment • Asympt – 19% vs 9% on treatment

34. Prolonged prophylaxis • Orthopedics • Post THA for 4-6 weeks with LMWH or warfarin, especially with Risk Factors • Obesity, sedentary, prior DVT • General surgery • Prolonged treatement with LMWH prevents out-pt DVTs but at a marginal cost that was deemed inappropriate

35. Screening for DVT? • Not in the asymptomatic pts….

36. Diagnostic strategy of DVT • Suspect • Dupplex • For proximal or ANY symptomatic – treat • For distal AND asymptomatic – follow with serial duplex US

37. Accuracy of Tests for Diagnosis of PE • Clinical suspicion is paramount

38. Diagnostic strategy for PE • Suspect • VQ • If normal AND D-Dimer low – ruled out • If high probability – start treatment • If indeterminate/nondiagnostic – angio, angio CT

39. Treatment • IV heparin, aPTT 1.5- 2.3 normal 5/7 • May use LMW • Coumadin INR 2-3 • Overlap heparin and warfarin 4/7 • On warfarin 3-6/12 • Consider ECHO/trop to evaluate RVF for PE to id High Risk pts.

40. Treatment • Hemodynamically unstable PE may require pressure support, fluid status monitoring, and/or thromolysis / surgery

41. Cases to consider • 38 yom for elective IHR • None, low risk • 65 yom for elective IHR • Moderate risk, Consider UN heparin pre-op, ambulation, stockings post op • 50 yom, obesity/CHF/prev DVT for IHR • High risk, consider LMWH preop/post op. Conisder warfarin

42. Cases concluded • 25 yof post severe head injury • High risk, mechanical, • 25 yom post trauma/abdo/chest • High risk, mechanical initially, consider LMWH when risk of bleeding is low • 75 yof post hip # • High, consider LMWH periop, warfarin or aspirin post op • 65 yom post THA, obese • High, consider LMWH periop, warfarin or aspirin post op