This document outlines the principles of deep vein thrombosis (DVT) prophylaxis. It discusses the definition, risk factors, investigations, and various forms of prophylaxis including mechanical methods like compression stockings and intermittent pneumatic compression, as well as pharmacological methods like heparin, low molecular weight heparin, warfarin, and dextran. It also covers timing of prophylaxis for pre-operative, intra-operative, post-operative periods, and recommends durations based on surgery type. Recent advances discussed include direct thrombin inhibitors like dabigatran.

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
– Post 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. Aetiopathogenesis
• 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

12. PATHOLOGY
• Thrombus is focally attached to the underlying vascular surface
• Tends to propagate toward the heart
• Composition- platelet
fibrin deposit
leucocytes
red blood cell
• Fate of a thrombus
Dissolution
Propragation
Embolisation
Reorganisation/recanalisation

13. 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

14. 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

15. 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,

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. PRINCIPLES OF PROPHYLAXIS
• Forms prophylaxis
– Mechanical
– Pharmacological

23. 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
• Inflammatory conditions of the lower leg
• Severe peripheral arterial disease
• Diabetic neuropathy (there is a risk of injury due to decreased
sensation and discomfort if there is a problem with the fitting)
• Severe oedema of the legs
• Unusual leg deformity
• Allergy to stocking material

24. Graduated Compression Stockings

25. 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

26. Intermittent pneumatic compression
devices

27. 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

28. Intermittent plantar venous
compression or foot impulse devices

29. PRINCIPLES OF PROPHYLAXIS
• Pharmacologic method
– Usually in the form of anticoagulation
– Not 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

30. 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

31. 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

32. 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)

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

34. 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
– Onset of action is usually 48 to 72 hours
– Usually commenced 3 to 4 days prior to elective
surgery
– Can also be used in conjunction with LMWH post-
operatively

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

36. 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 Index
• 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

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

38. PRINCIPLES OF PROPHYLAXIS
• PRE-OPERATIVE MEASURES:
– Careful preoperative assesment
• History taking
• Physical examination
• stratification
– Optimization of any comorbid illness
• Correction of anaemia
• Resolution of infection
• Correction of electrolyte imbalance
– Weight reduction
– Adequate hydration
– Deep breathing exercises/Freq.movt of Llimbs

39. 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-op

40. 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
– Admit 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

41. PRINCIPLES OF PROPHYLAXIS
• INTRA-OPERTIVE MEASURES:
– Patient positioning
• Avoid hard surfaces
• Avoid legs beyond operation table
– Choice of anaesthesia
• Regional 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

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

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

44. 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
– Current 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

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

46. RECENT ADVANCES
• Direct thrombin inhibitors
– Hirudin
• More 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

47. RECENT ADVANCES
• Direct thrombin inhibitors
– Others include;
• Bivalirudin
• Argatroban
• Ximelagatram

48. RECENT ADVANCES
• Factor Xa inhibitors
– Fondaparinux
• Is 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

49. 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

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

51. CONCLUSION
• DVT is a serious life threatening condition, but
preventable
• High 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

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

53. 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,
5th ed. 2015, vol I; 15: 252-255
• Richard N. Mitchell; Hemodynamic Disorders,
Thromboembolism, and Shock, in Robbin’s Basic
Pathology, 9th ed. 2013; 3:79-93
• Helgi Johannsson and Vafa Mansoubi; Care of the
patient in the peri- operative period, in Essential
Surgical Practice, 5th ed. 2015; 4: 98-99

54. REFERENCES
• James L. Zehnder, MD; Drugs used in the disorders of
coagulation, in Basic and Clinical Pharmacology 12th 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