Principles of dvt prophylaxis

power point

1. PRINCIPLES OF DVT PROPHYLAXIS SANUSI A.A DEPT OF ORTHOPAEDICS AND TRAUMA JUTH

2. OUTLINE Introduction Definition Statement of surgical importance Epidemiology Aetiopathogenesis Pathophysiology Risk factors Pathology Clinical features

3. OUTLINE Investigations Principles of prophylaxis Definition Risk assessment Forms of prophylaxis Mechanical pharmacological Pre operative prophylaxis Intra operative prophylaxis P ost operative prophylaxis Timing and duration of prophylaxis

4. OUTLINE Current trends Peculiarities in our environment Conclusion References

5. INTRODUCTION Definition Venous thrombosis is the formation of semi-solid coagulum in the venous system of a living individual It can be Phlebothrombosis otherwise called DVT, or Thromboplhebitis which occurs in superficial veins Statement of surgical importance It is a preventable complication that occurs in hospitalized patient, esp. surgical patients ( 30%) It contributes to longer hospital stay, morbidity and mortality

6. INTRODUCTION Epidemiology Incidence: 100 per 100,000 per year in US Paucity of local data Up to 90% of DVT occurs in the lower extremity and accounts for the majority of morbidity and complications Incidence increase after 40 years of age 20% of diagnosis are made within 3 months of surgical procedure

7. Aetiopathogenesis Pathopysiology VIRCHOW’S TRIAD ABNORMAL BLOOD FLOW- STASIS OR TURBULENT BLOOD ENDOTHELIA INJURY INTRINSIC OR EXTRINSIC HYPERCOAGUBILITY THROMBUS-INBALANCE BETWEEN ANTITHROMBOTIC AND PROTHROMBOTIC FACTORS/PROPERTIES

8. A etiopathogenesis Risk factors for venous thromboembolism Acquired Advanced age Hospitalization/immobilization (>3 days) Hormone replacement therapy and oral contraceptive use Pregnancy and puerperium Prior venous thromboembolism Malignancy Major surgery Obesity

9. Aetiopathogenesis Risk factors for venous thromboembolism Acquired Nephrotic syndrome Trauma or spinal cord injury Long-haul travel (>6 hours) Varicose veins Antiphospholipid antibody syndrome Myeloproliferative disease Polycythemia

10. Aetiopathogenesis Risk factors for venous thromboembolism Inherited Factor V Leiden Prothrombin 20210A Antithrombin deficiency Protein C deficiency Protein S deficiency Factor XI elevation Dysfibrinogenemia

11. PATHOLOGY T hrombus is focally attached to the underlying vascular surface T ends to propagate toward the heart Composition- platelet fibrin deposit leucocytes red blood cell F ate of a thrombus Dissolution Propragation E mbolisation R eorganisation / recanalisation

12. CLINICAL FEATURES Asymptomatic in about 2/3 of cases Most common presentation- pain and swelling especially in the calf Usually unilateral, however it can occur bilaterally in up to 30% of cases Some patient may first present with features of pulmonary embolism- pleuritic chest pain, haemoptysis , shortness of breath

13. CLINICAL FEATURES Examination may reveal low grade fever erythema over the calf and leg superficial venous dilatation oedema of the leg and feet below the point of obstruction May also elicit tenderness in the calf Homan’s sign may be positive

14. INVESTIGATIONS Routine investigations include - Full blood count, including platelet count - Coagulation studies: PT, PTT, INR, Clotting factor estimations, To detect underlying conditions: - CXR, ECG, echocardiography - LFT, RFT,

15. INVESTIGATIONS To determine the presence and extent of DVT and its complications Duplex Ultrasonography Impedance plethysmography Contrast venography 125I labelled fibrinogen scintigraphy Magnetic Resonance Venography Contrast enhanced CT scanning D dimer

16. PRINCIPLES OF PROPHYLAXIS Prophylaxis means prevention of a disease or protective treatment for a disease DVT prophylaxis involves measures aim at preventing surgical patient at risk of DVT from developing it The goal is to reduce morbidity and mortality associated with venous thromboembolism

17. PRINCIPLES OF PROPHYLAXIS Risk assessment - The Thromoembolic Risk Factor ( THRiFT ) Consensus Group Low risk group Minor operations Major operations in patients <40yrs No other risk factors Prophylaxis – early mobilization

18. PRINCIPLES OF PROPHYLAXIS Moderate risk group Major surgery Age 40+ or other risk factors Major medical illness: heart/lung disease, cancer, inflammatory bowel disease Major trauma/burns Minor surgery, trauma, medical illness in patient with previous DVT, PE or thrombophilia Prophylaxis – early mobilization and specific prophylaxis

19. PRINCIPLES OF PROPHYLAXIS High risk group Major orthopaedic surgery for fracture pelvis, hip, lower limb Major abdominal/pelvic surgery for cancer Major surgery, trauma, medical illness in patient with previous DVT , PE or thrombophilia Lower limb paralysis (e.g. stroke, paraplegia) Major lower limb amputation Prophylaxis – early mobilization and specific prophylaxis

20. PRINCIPLES OF PROPHYLAXIS Wells Score: Clinical probability of Deep Vein Thrombosis Active Cancer + 1 Paralysis , paresis , or recent plaster immobilisation + 1 Recently bedridden (>3 days) or major surgery past 4 weeks + 1 Localised tenderness along deep venous system + 1 Entire limb swollen + 1 Calf swelling by more than 3cm compared to asymptomatic leg + 1 Previously documented DVT + 1 Pitting oedema - greater in the symptomatic leg + 1 Dilated collateral superficial veins (non-varicose) + 1 Alternative diagnosis likely or more possible than DVT - 2 DVT likely: 2 points or more DVT unlikely: 1 point or less

21. PRINCIPLES OF PROPHYLAXIS Forms prophylaxis Mechanical Pharmacological

22. PRINCIPLES OF PROPHYLAXIS Mechanical methods Graduated Compression Stockings (GCS) Stockings must be removed daily to assess skin condition and perfusion and to provide skin care Contra indications Morbid obesity where correct fitting cannot be achieved I nflammatory conditions of the lower leg S evere peripheral arterial disease D iabetic neuropathy (there is a risk of injury due to decreased sensation and discomfort if there is a problem with the fitting ) S evere oedema of the legs U nusual leg deformity A llergy to stocking material

23. Graduated Compression Stockings

24. PRINCIPLES OF PROPHYLAXIS Intermittent pneumatic compression (IPC) Must be applied early enough, preferably immediately pre-op, and properly Must be applied at regular intervals Improves venous return, stimulates fibrinolytic activity, reduces venous endothelial injury due to venodilation during surgery Impractical for patients undergoing operations at or below the knee

25. Intermittent pneumatic compression devices

26. PRINCIPLES OF PROPHYLAXIS Intermittent plantar venous compression or foot impulse devices (FID) Also aids venous drainage It should not be used in combination with compression stockings as these impair refill of the venous plexus after emptying by the foot pump

27. Intermittent plantar venous compression or foot impulse devices

28. PRINCIPLES OF PROPHYLAXIS Pharmacologic method U sually in the form of anticoagulation N ot to be used alone, but with the mechanical means of prophylaxis Anticoagulation regimes include: - Low dosage unfractionated heparin (UFH) - Low molecular weight heparin (LMWH) - Warfarin - Dextran 70

29. PRINCIPLES OF PROPHYLAXIS Low dose UFH Binds to antithrombin and increases it activity by over 1000-fold The antithrombin -heparin complex primarily inhibits factor IIa (thrombin) and factor Xa and, to a lesser degree IXa , XIa , and XIIa In addition, UFH also binds to tissue factor pathway inhibitor , which inhibits the conversion of factor X to Xa , and factor IX to IXa . It also catalyzes the inhibition of thrombin by heparin cofactor II via a mechanism independent of antithrombin

30. PRINCIPLES OF PROPHYLAXIS Low dose UFH Has been used with safety in patients with moderate risk 5,000iu 2hrs pre-op subcutaneously and then 12 hrly post-op for 6 days provides good prophylaxis Patients with higher risk require larger doses The level of antithrombotic therapy should be monitored every 6 hours using the activated partial thromboplastin time ( aPTT ), with the goal range of 1.5 to 2.5 times control values

31. PRINCIPLES OF PROPHYLAXIS Low dose UFH Advantage is its cheapness Complication; haemorrhage , heparin induced thrombocytopaenia Antidote is protamine sulphate IV at a dose of 100iu ( lmg )

32. PRINCIPLES OF PROPHYLAXIS LMWH produced by enzymatic depolarization of heparin Also binds to anti thrombin Advantages A re more effective anticoagulants than heparin Increased bioavailabilty Longer half-life More predictable elimination rate Do not need laboratory monitoring D ecrease in thrombotic complications, bleeding, and mortality Example- enoxaparin , dalteparin Dose- Enoxaparin 2,500iu/day , dalteparin 20mg/day

33. PRINCIPLES OF PROPHYLAXIS Warfarin oral anticoagulant Inhibits the γ- carboxylation of vitamin K–dependent procoagulants ( factors II , VII, IX, and X) and anticoagulants (proteins C and S), resulting in formation of less functional proteins O nset of action is usually 48 to 72 hours U sually commenced 3 to 4 days prior to elective surgery C an also be used in conjunction with LMWH post-operatively

34. PRINCIPLES OF PROPHYLAXIS Warfarin Dose-: 5-10mg dialy Cheap and easy to use Good patient compliance The primary complication of warfarin therapy is hemorrhage W arfarin anticoagulation may be reversed by O mitting or decreasing subsequent dosages, A dministering oral or parenteral vitamin K, or A dministering fresh-frozen plasma, prothrombin complex concentrate, or recombinant factor VIIa

35. PRINCIPLES OF PROPHYLAXIS Warfarin Monitoring warfaring therapy This is done by measuring the INR (2.0-3.0) INR = (patient prothrombin time/laboratory normal prothrombin time) ISI ISI is the International Sensitivity I ndex The ISI describes the strength of the thromboplastin that is added to activate the extrinsic coagulation pathway The ISI is usually between 0.94-1.40 for more sensitive and 2.0-3.0 for less sensitive thromboplastin A high INR indicates a higher risk of bleeding while a low INR suggests a higher risk of developing thrombus

36. PRINCIPLES OF PROPHYLAXIS Dextran 40/70 A ntiplatelet substance Also induces decreased level of FV III by precipitation and ligand binding A dministered by intravenous infusion 500-1000ml of dextran is started after induction of anaesthesia It is repeated daily until the patient is ambulant. C an cause coagulation defects, allergic reactions, and volume overload which can cause cardiac failure in the elderly

37. PRINCIPLES OF PROPHYLAXIS PRE-OPERATIVE MEASURES: Careful preoperative assesment History taking Physical examination stratification Optimiz a tion of any comorbid illness Correction of anaemia Resolution of infection Correction of electrolyte imbalance W eight reduction Adequate hydration Deep breathing exercises/Freq.movt of Llimbs

38. PRINCIPLES OF PROPHYLAXIS PRE-OPERATIVE MEASURES Short pre-op hosp. stay (1-2days b4 surgery) Stoppage of OCP 1/12 b4 surgery Heparin 5000units S.C. 2hrs pre-op LMWH-20mg 2hrs pre-o p

39. PRINCIPLES OF PROPHYLAXIS PRE-OPERATIVE MEASURES Patient on warfarin Low risk withhold warfarin 4 days before operation and restart once the risk of bleeding is low postoperatively Moderate risk stop warfarin as above, but cover with a treatment dose of low-molecular-weight heparin starting the day after warfarin has been stopped High risk Stop warfarin as above A dmit the patient the day before surgery and commence an unfractionated heparin infusion. Stop 2 hours preoperatively, measure the activated partial thromboplastin time And restart as soon as the risk of bleeding is low

40. PRINCIPLES OF PROPHYLAXIS INTRA-OPERTIVE MEASURES: Patient positioning Avoid hard surfaces Avoid legs beyond operation table Choice of anaesthesi a R egional anaesthesia reduces incidence of DVT by 31% Reduces postoperative blood hypercoagulability It increases arterial inflow and venous emptying rate of the lower extremities Electrical stimulation of calf

41. PRINCIPLES OF PROPHYLAXIS INTRA-OPERTIVE MEASURES Passive leg exercise(foot pedalling machine) I ntermittent pneumatic compressn of calf Meticulously performed surgery Dextran 40/70 started at induction of anaesthesia

42. PRINCIPLES OF PROPHYLAXIS POST-OPERATIVE MEASURES: Early mobilization,massage & leg movt Deep breathing exercise Adequate hydration Adequate analgesia Graduated compression stocking Continue anticoagulat ion therapy Early discharge

43. PRINCIPLES OF PROPHYLAXIS Timing and duration of prophylaxis Predisposition can be pre, intra or post op The ideal duration of thromboprophylaxis is not known Traditionally it is continued until the patient is fully mobile Thromboprophylaxis should be prolonged for some time after discharge from hospital The precise period depends on many factors C urrent evidence supports 14 days for knee replacement and 4–5 weeks for hip replacement and hip fracture Oral agents facilitate effective and practical extended duration prophylaxis

44. RECENT ADVANCES Direct thrombin inhibitors Dabigatran etexilate mesylate I s the first oral direct thrombin inhibitor approved by the FDA Predictable pharmacokinetics and bioavailability, which allow for fixed dosing P redictable anticoagulant response, and make routine coagulation monitoring unnecessary H alf-life of the drug is about 12–17 hours T he primary toxicity of dabigatran is bleeding There is no antidote for dabigatran Formulations- 110mg, 150mg, 75mg

45. RECENT ADVANCES Direct thrombin inhibitors Hirudin M ore effective and as safe as LMWH Commercially available hirudin is manufactured using recombinant DNA technology. It is indicated for the prophylaxis and treatment of patients with HIT. In patients with normal renal function, it is administered as an IV bolus dose of 0.4 mg/kg, followed by a continuous IV infusion of 0.15 mg/kg per hour. The half-life ranges from 30 to 60 minutes. The aPTT is monitored and dosage is adjusted to maintain an aPTT of 1.5 to 2.5 times the laboratory normal value No antidote

46. RECENT ADVANCES Direct thrombin inhibitors Others include; Bivalirudin Argatroban Ximelagatram

47. RECENT ADVANCES Factor Xa inhibitors Fondaparinux I s a synthetic pentasaccharide Binds and activates antithrombin , causing specific inhibition of factor Xa The drug is administered SC once daily with a weight-based dosing protocol: 5 mg, 7.5 mg, or 10 mg for patients weighing <50 kg, 50 to 100 kg, or >100 kg, respectively . The half-life of fondaparinux is approximately 17 hours in patients with normal renal function

48. RECENT ADVANCES Factor Xa inhibitors Rivaroxaban An oral direct factor Xa inhibitor Approved for prevention of venous thromboembolism following hip or knee surgery The prophylactic dose is 10 mg orally daily

49. PECULIARITIES IN OUR ENVIRONMENT Most cases go unnoticed High cost of medications Unavailability of newer agents

50. CONCLUSION DVT is a serious life threatening condition, but preventable H igh index of suspicion and prophylaxis in risk group is key to reducing the attendant mortality and morbidity Development & frequent review of DVT prophylaxis guidelines in every hospital is of paramount importance

51. REFERENCES Selvadurai N, David Warwick; Thromboprphylaxis , in Apley’s System of Orthopaedics and Fractures, 9 th ed. 2010; 12: 307-311 Jason P. Jundt et al; Venous and Lymphatic Disease, in Schwartz Principles of Surgery, 10 th ed. 2015; 24: 918-927 Peter McCollum and Ian Chetter ; Venous Disorder, in Bailey and Love’s Short Practice of Surgery, 26 th ed. 2013; 57: 913-917

52. REFERENCES E. Aniteye , L. Wu; Peri -operative care and Post operative complications, in BAJA’s Principles and Practice of Surgery in the Tropics including Pathology, 5 th ed. 2015, vol I; 15: 252-255 Richard N. Mitchell; Hemodynamic Disorders, Thromboembolism , and Shock, in Robbin’s Basic Pathology, 9 th ed. 2013; 3:79-93 Helgi J ohannsson and V afa Mansoubi ; Care of the patient in the peri - operative period, in Essential Surgical Practice, 5 th ed. 2015; 4: 98-99

53. REFERENCES James L. Zehnder , MD; Drugs used in the disorders of coagulation, in Basic and Clinical Pharmacology 12 th ed. 2012; 34:601-618 www.health.nsw.gov.au/policies/Prevention of Venous Thromboembolism Molly S. Judge et al; Current concepts in deep venous thrombosis prophylaxis; www.mollyjudge.com/publications/swelling/DVT