What are the options for DVT prophylaxis in patients undergoing joint replacement procedures?
DVT risk varies with the procedure, with hip replacement being higher risk than knee replacement. Guidelines in this area are changing as new therapies are developed, but the following are options for DVT prophylaxis:
• Warfarin, with dose adjustment to reach a target international normalized ratio of 2–3 for at least 10 days after the procedure. Continuing warfarin for up to 42 days postoperatively may be associated with decreased DVT in patients after hip surgery. Dosing for longer than 10 days after knee replacement surgery has not been shown to be beneficial.
• Heparin (unfractionated) 5000 units subcutaneously before surgery, then 5000 units every 8 hours after surgery, adjusted by sliding scale every day to maintain the adjusted partial thromboplastin time within 4 seconds of the upper limit of normal. Time and expense of administration of this agent limit its usefulness.
• Pneumatic compression devices, worn on the lower extremities at all times starting the morning of surgery, until the patient is ambulatory or discharged. Compression stockings only offer minimal protection against DVT, and the effectiveness of this approach as single therapy has not been determined in patients with rheumatic disease (many of whom are at elevated risk of clot).
• Low molecular weight heparins (LMWHs) may be used for prophylaxis. The best efficacy is achieved by starting preoperatively and continuing for at least 10 days postoperatively. In hip replacement surgery, continued DVT prophylaxis with LMWHs up to 42 days postoperatively has been shown to decrease the incidence of DVT without significantly increasing bleeding episodes.
• Fondaparinux (synthetic heparin) preoperatively and continued for 10–42 days postoperatively.
• Aspirin (325 mg/day) can modestly decrease the incidence of DVT, but is associated with an increased risk of bleeding and is not routinely recommended for perioperative DVT prophylaxis.
The newer anticoagulants including the direct acting oral anticoagulants such as apixaban and rivaroxaban have not been extensively studied in DVT prevention around surgeries, and therefore, current guidelines do not provide recommendations on these agents.