What is the role of subcutaneous (subQ) heparin for deep vein thrombosis (DVT) prophylaxis (ppx) prior to orthopedic surgery?

From the Guidelines

Subcutaneous (subQ) low molecular weight heparin (LMWH) is recommended for deep vein thrombosis (DVT) prophylaxis in patients undergoing orthopedic surgery, with the preferred agent being enoxaparin (Lovenox) at a dose of 30 mg twice daily, starting 12 hours before surgery, and continuing for 10-35 days postoperatively 1. The use of LMWH for DVT prophylaxis in orthopedic surgery patients is supported by several studies, including a guideline published in the Chest journal, which recommends that all patients undergoing major orthopedic surgery receive prophylaxis with a pharmacologic agent or intermittent pneumatic compression device (IPCD) for a minimum of 10 to 14 days, and suggests extending prophylaxis for up to 35 days 1. Some key points to consider when using LMWH for DVT prophylaxis in orthopedic surgery patients include:

• The dose and duration of LMWH therapy, with enoxaparin typically administered at a dose of 30 mg twice daily, starting 12 hours before surgery, and continuing for 10-35 days postoperatively 1
• The use of alternative LMWH options, such as dalteparin (Fragmin) at 5,000 units once daily starting 12 hours before surgery 1
• The importance of dose adjustments for patients with renal impairment (CrCl <30 mL/min) or low body weight (<50 kg) 1
• The mechanism of action of LMWH, which works by binding to antithrombin and enhancing its inhibition of factor Xa, thereby preventing clot formation 1 Overall, the use of LMWH for DVT prophylaxis in orthopedic surgery patients is a crucial aspect of preventing venous thromboembolism, which is a significant complication of orthopedic surgery due to venous stasis, endothelial injury during surgery, and hypercoagulability from the inflammatory response to surgery.

From the FDA Drug Label

A number of well-controlled clinical trials have demonstrated that low-dose heparin prophylaxis, given just prior to and after surgery, will reduce the incidence of postoperative deep vein thrombosis in the legs (as measured by the I-125 fibrinogen technique and venography) and of clinical pulmonary embolism The most widely used dosage has been 5,000 units 2 hours before surgery and 5,000 units every 8 to 12 hours thereafter for seven days or until the patient is fully ambulatory, whichever is longer. The heparin is given by deep subcutaneous injection in the arm or abdomen with a fine needle (25 to 26 gauge) to minimize tissue trauma. Such prophylaxis should be reserved for patients over the age of 40 who are undergoing major surgery.

The recommended dosage of subQ heparin for DVT prophylaxis prior to orthopedic surgery is 5,000 units 2 hours before surgery and 5,000 units every 8 to 12 hours thereafter for seven days or until the patient is fully ambulatory, whichever is longer 2. Key points:

• Administration: deep subcutaneous injection in the arm or abdomen with a fine needle (25 to 26 gauge)
• Patient selection: patients over the age of 40 who are undergoing major surgery
• Duration: seven days or until the patient is fully ambulatory, whichever is longer

From the Research

Subcutaneous Heparin for DVT Prophylaxis in Orthopedic Surgery

• The use of subcutaneous heparin for deep vein thrombosis (DVT) prophylaxis in orthopedic surgery is a common practice, as DVT is a significant cause of morbidity after such surgeries 3.
• Studies have shown that pharmacological primary prophylaxis of venous thromboembolism (VTE) is associated with a decrease in the incidence of DVT and related complications, with low-dose unfractionated heparin being one of the options 3, 4.
• However, the main limitation of VTE prophylaxis with anticoagulant drugs is the risk of bleeding, and both pharmacological and non-pharmacological measures are available for DVT prophylaxis 3.
• The American College of Chest Physicians (ACCP) recommends the use of low-molecular-weight heparin (LMWH), fondaparinux, or adjusted-dose warfarin as preferred VTE prophylaxis in patients undergoing hip or knee arthroplasty 4.
• Extended-duration prophylaxis (for 4 to 5 weeks) is now recommended for patients undergoing hip arthroplasty or hip fracture repair 4, 5.

Comparison of Anticoagulants for DVT Prophylaxis

• A meta-analysis comparing direct oral anticoagulants (DOACs) with LMWH for thromboprophylaxis in orthopedic surgery found that DOACs were associated with a significant reduction of major VTE and DVT, but not pulmonary embolism (PE) 6.
• The study also found no statistically significant difference between DOACs and LMWH in terms of major bleeding, clinically relevant non-major bleeding, all-cause mortality, VTE-related mortality, and bleeding-related mortality 6.
• Another study found that LMWH appears to be more effective than unfractionated heparin (UFH) for VTE prophylaxis in non-orthopedic surgery 5.

Guidelines and Recommendations

• Guidelines recommend the use of LMWH, fondaparinux, or adjusted-dose warfarin for VTE prophylaxis in patients undergoing major orthopedic surgery 4, 5.
• The use of aspirin as an option for VTE prophylaxis after total hip arthroplasty, total knee arthroplasty, and hip fracture surgery is also recognized 5.
• However, prophylactic inferior vena cava (IVC) filter placement or surveillance compression ultrasonography is not recommended in the management or detection of VTE in surgical patients 5.