What is the recommended duration of heparin (unfractionated heparin) 5000 units subcutaneously every 8 hours for Deep Vein Thrombosis (DVT) prophylaxis in a patient with a hip fracture?

Duration of Heparin Prophylaxis for Hip Fracture Patients

Patients with hip fractures should receive unfractionated heparin 5000 units subcutaneously every 8 hours for a minimum of 10-14 days, with strong consideration for extending prophylaxis to 28-35 days post-operatively. 1, 2

Recommended Duration of Prophylaxis

• For hip fracture surgery, thromboprophylaxis should be started before or as soon as possible after surgery and continued for a minimum of 7-10 days 1
• Extended prophylaxis of 28-35 days (4 weeks) is strongly recommended for hip fracture patients due to their high risk of venous thromboembolism 2
• The American Academy of Orthopaedic Surgeons specifically recommends administering thromboprophylaxis for 4 weeks (28 days) postoperatively in hip fracture patients 2

Dosing Regimen

• Unfractionated heparin (UFH) 5000 units subcutaneously every 8 hours is the recommended dosing frequency for high-risk patients, including those with hip fractures 3, 4
• The every 8-hour dosing schedule is more effective than every 12-hour dosing, particularly in high-risk patients such as those with hip fractures 3
• The FDA-approved dosing for low-dose prophylaxis of postoperative thromboembolism is 5000 units subcutaneously every 8 to 12 hours, with the more frequent dosing preferred for higher-risk patients 4

Evidence Supporting Extended Prophylaxis

• Studies have shown that the risk of venous thromboembolism remains elevated for several weeks after hip fracture surgery 1, 2
• A randomized trial demonstrated that prophylaxis with unfractionated heparin significantly reduced the incidence of fatal pulmonary embolism in hip fracture patients compared to no prophylaxis (0% vs 3.5%) 5
• Inadequate duration of prophylaxis is a common error in VTE prevention after hip fracture surgery 2

Considerations for Special Populations

• For patients weighing more than 100 kg, the every 8-hour dosing schedule is particularly important to ensure adequate prophylaxis 3
• Unfractionated heparin is preferred over low molecular weight heparin in patients with severe renal impairment (creatinine clearance <30 mL/min) 1, 3
• Elderly patients may require careful monitoring but still benefit from standard prophylactic dosing 4

Potential Pitfalls

• Using every 12-hour dosing in high-risk patients like those with hip fractures may lead to subtherapeutic prophylaxis and increased VTE risk 3
• Discontinuing prophylaxis too early (before 10-14 days) significantly increases the risk of venous thromboembolism 1, 2
• Failure to extend prophylaxis beyond the hospital stay is a common error, as the risk of VTE remains elevated for several weeks after hip fracture surgery 2

Alternative Options

• If unfractionated heparin is contraindicated, low molecular weight heparins like enoxaparin (30 mg twice daily) can be considered for patients with normal renal function 1, 2
• For patients with a history of heparin-induced thrombocytopenia, fondaparinux (2.5 mg once daily) may be an alternative option 1
• Mechanical prophylaxis alone is insufficient for hip fracture patients unless there are absolute contraindications to pharmacological prophylaxis 2