Current Concepts With DVT Prophylaxis
When and how should you administer prophylaxis to patients to prevent the potential complication of deep vein thrombosis (DVT) following lower extremity surgery? These authors discuss the risk factors for DVT and examine the research on whether one should provide prophylaxis.
Deep venous thrombosis (DVT) is a rare yet potentially devastating complication of foot and ankle surgery. While many DVTs may remain subclinical or asymptomatic, DVT is a risk factor for a potentially fatal pulmonary embolism.
The majority of the research on DVT after surgery is based on patients who have undergone knee or hip arthroplasty. The published rate of DVT after these procedures ranges from 45 to 84 percent without prophylaxis.1 Only recently have there been more in-depth studies on the rates of DVT in foot and ankle surgery.
In order to appropriately manage the risks and benefits of DVT prophylaxis in patients undergoing foot and ankle surgery, surgeons must be aware of the pathophysiology of deep vein thrombosis, the risks of DVT for the proposed surgery, the risk of complications from anticoagulation and the various options available for prophylaxis today. While it is important to understand treatment options, it is equally important to understand that there are wide gaps in the literature regarding DVT after foot and ankle surgery.
Deep vein thrombosis is defined as the formation of a blood clot or thrombus in a deep vein. While it may occur in any deep vein, it is most common in the veins of the lower extremity and pelvic region. When this clot dislodges and travels to the pulmonary vasculature, this then becomes a pulmonary embolism. These are collectively known as venous thromboembolism (VTE).
Key Risk Factors For DVT
Virchow’s triad of risk factors for DVT consists of vascular endothelial injury, venous stasis and the existence of a hypercoagulable state. Hypercoagulable states can include the presence of malignancy, smoking, the use of oral contraceptives or hormone replacement therapy, congestive heart failure, inflammatory bowel disease, pregnancy and obesity. Inherited hypercoagulable states also exist and include factor 5 Leiden deficiency.1
The most important risk factor for DVT, however, is a history of prior DVT. As such, it is imperative that the foot and ankle surgeon perform a thorough preoperative history that includes not only a personal history of risk factors for DVT but a family history as well. Also bear in mind that females have a higher risk of DVT than males.1
Another important arm of Virchow’s triad is venous stasis. One can minimize this during the perioperative period by using sequential compression devices on the non-operative extremity.2 During hospitalization, one may use compression devices bilaterally but use caution in the setting of peripheral vascular disease.
If permissible, early mobilization and early weightbearing may also serve to reduce venous stasis and reduce the risk of DVT.3 If patients are not immobilized at the ankle, encourage them to begin ankle range of motion as early as is surgically permissible. Whether below knee cast immobilization is a risk factor for DVT remains controversial. Some studies identify it as a risk factor and some studies do not. Reported rates of DVT in those with below knee cast immobilization range from 2.7 to 14.8 percent.4 One study on cast immobilization demonstrated a 6.3 percent rate of DVT and 1.44 percent for pulmonary embolism without prophylaxis for the conservative treatment of a tendo-Achilles rupture.4
When taking this into consideration with other risk factors, the need for prolonged immobilization may influence the surgeon’s decision on whether to initiate DVT prophylaxis in the postoperative setting.