SearchVTE Prevention in Surgical Patients
Challenges in selecting optimal therapy
Therapies employed to prevent venous thromboembolism (VTE) in surgical patients vary in efficacy, ease of use, and risk of bleeding.3, 55 The standard of care, as reflected in current guidelines, is to use low-molecular-weight heparin (LMWH), fondaparinux, or a vitamin K antagonist (VKA) for thromboprophylaxis after surgery for hip or knee replacement and hip fracture. For abdominal surgery, where the risk of VTE is generally lower than in major orthopaedic surgery, low-dose unfractionated heparin (LDUH) or LMWH can be used. Because of the convenience of less-frequent dosing, LMWH has generally replaced LDUH. Mechanical devices are an appropriate option in patients at high risk of bleeding complications and can be used as an adjunct to anticoagulation in other surgical patients.3
Greater efficacy may be associated with increased bleeding risks
Clinical trials and meta-analyses comparing agents have generally shown LMWH and fondaparinux to be roughly equivalent and VKAs to be less effective for thromboprophylaxis in major orthopaedic surgery. For abdominal surgery, the balance of evidence indicates that LDUH is as effective as LMWH. It is important to note that with currently available treatment options, regimens associated with higher efficacy are often also associated with increased bleeding risks.3
A number of studies have focused on the timing of perioperative anticoagulation. The goal is to balance prevention of postoperative bleeding against the risk of early deep-vein thrombosis (DVT).55 Temporal patterns of prophylactic treatment employed in an effort to achieve this goal vary from region to region.
Warfarin: challenges in the outpatient setting
In North America, warfarin is the most common agent used for thromboprophylaxis in patients undergoing hip arthroplasty. Outpatient use of warfarin, however, requires extensive monitoring and dose adjustments, which may account for why European orthopaedic surgeons have largely abandoned its use in favour LMWH. The delayed onset of action of warfarin may prevent excessive bleeding perioperatively, but it also increases the risk of early thrombosis.3
Duration of treatment: an important aspect of care
The duration of anticoagulation needed to prevent DVT after hospital discharge is an important aspect of care. Current guidelines recommend extending prophylaxis for 10 days after knee arthroplasty and for four to six weeks after hip arthroplasty and hip fracture surgery. Extending prophylaxis for four weeks is also recommended for patients after abdominal cancer surgery.3, 60, 62 However, in practice, many patients may not receive this duration of treatment.118
- 3 - Geerts WH, Bergqvist D, Pineo GF, Heit JA, Samama CM, Lassen MR, and Colwell CW. Prevention of Venous Thromboembolism: American College of Chest Physicians (ACCP) Evidence-Based Clinical Practice Guidelines (8th Edition). Chest. Jun 2008: 381S–453S.
- 55 - Kakkar AK. Prevention of venous thromboembolism in general surgery. In: Colman RW, Clowes AW, George JN, Goldhaber SZ, Marder VJ, eds. Hemostasis and Thrombosis: Basic Principles and Clinical Practice. 5th ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2006:1361-1367.
- 60 - Nicolaides AN, Fareed J, Kakkar AK, et al. Prevention and treatment of venous thromboembolism. International Consensus Statement (guidelines according to scientific evidence). Int Angiol. 2006;25(2):101-161.
- 62 - Lyman GH, Khorana AA, Falanga A, et al; American Society of Clinical Oncology. American Society of Clinical Oncology guideline: recommendations for venous thromboembolism prophylaxis and treatment in patients with cancer. J Clin Oncol. 2007;25(34):5490-5505.
- 118 - Anderson FA Jr, Hirsh J, White K, Fitzgerald RH Jr; Hip and Knee Registry Investigators. Temporal trends in prevention of venous thromboembolism following primary total hip or knee arthroplasty 1996-2001: findings from the Hip and Knee Registry. Chest. 2003;124(6 suppl):349S-356S.
- Fondaparinux
- An indirect Factor Xa inhibitor comprising a synthetic pentasaccharide sequence matching the part of the heparin molecule that binds to antithrombin. It is administered by subcutaneous injection.
- Heparin
- An anticoagulant that exerts its activity by binding to antithrombin and greatly increasing its activity. The principal coagulation factors inhibited by heparin are Factors IIa and Xa. It is administered by intravenous or subcutaneous injection.
- Thromboprophylaxis
- The use of medication or medical devices to prevent the formation of blood clots.
- Vitamin K
- An essential cofactor in the carboxylation of glutamic residues on the procoagulant forms of Factors II, VII, IX, and X. This ultimately leads to increased formation of thrombin and fibrin.
- Venous thromboembolism
- A condition in which a blood clot (thrombus) forms in a vein, which in some cases then breaks free and enters the circulation as an embolus, finally lodging in and completely obstructing a blood vessel, e.g., in lungs causing a PE. The term encompasses both DVT and PE.
- Low-molecular-weight heparin
- An anticoagulant derived from unfractionated heparin (UFH), containing only the low-molecular-weight molecules of heparin. It binds to antithrombin, greatly increasing its activity. It inhibits coagulation Factor Xa and, to a lesser extent, Factor IIa. LMWHs are administered by subcutaneous injection.
- Warfarin
- A vitamin K antagonist. Most commonly used oral anticoagulant in chronic prevention or treatment of VTE.
- Prophylaxis
- The prevention of a disease or pathological condition.
