22.23: Venous Thrombosis III: Interprofessional Care

Venous thrombosis requires effective prevention and treatment strategies to improve patient outcomes and reduce potential complications.

Prevention Strategies

Healthcare providers must prioritize preventing venous thromboembolism (VTE) for all adult patients upon admission. Interventions depend on bleeding and thrombosis risk, medical history, current medications, diagnoses, planned procedures, and patient preferences. Patients on bed rest should change positions every two hours and, if not contraindicated, perform foot, knee, and hip exercises every 2 to 4 hours while awake. Those who can mobilize should sit up for meals and walk four to six times daily.

Graduated compression stockings or intermittent pneumatic compression devices (IPCs) are essential for VTE prevention. Graduated compression stockings enhance blood flow in the legs, reduce venous stasis, and prevent clot formation. Their effectiveness is enhanced when combined with anticoagulation therapy. IPCs use inflatable sleeves on the calves, thighs, and sometimes feet and ankles to improve venous return by intermittently inflating and deflating. IPCs are typically used in patients who are at high risk for VTE, particularly when compression stockings are contraindicated or insufficient.

Treatment Strategies

Drug Therapy

Anticoagulants are crucial for VTE prevention and treatment, tailored to the patient's risk level. Prevention aims to stop clot formation, while treatment goals include preventing new clots, clot spread, and embolization. The three main classes of anticoagulants are vitamin K antagonists (VKAs), thrombin inhibitors, and factor Xa inhibitors.

• Vitamin K Antagonists: Warfarin, an oral VKA, is used for long-term anticoagulation. It inhibits the activation of vitamin K-dependent coagulation factors II, VII, IX, and X, as well as anticoagulant proteins C and S.
• Thrombin Inhibitors: Thrombin inhibitors are categorized into indirect and direct types. Indirect thrombin inhibitors include unfractionated heparin (UH) and low molecular weight heparins (LMWHs). Unfractionated heparin is administered subcutaneously for VTE prevention or via continuous IV infusion for treatment, requiring regular monitoring of clotting status using activated partial thromboplastin time (aPTT). LMWHs, like enoxaparin, are derived from UH, have more predictable dose responses, longer half-lives, and fewer bleeding complications, typically not requiring ongoing anticoagulant monitoring and dose adjustment. Direct thrombin inhibitors, such as hirudin derivatives (e.g., lepirudin), inhibit thrombin directly without causing plasma protein and platelet interactions.
• Factor Xa Inhibitors: Factor Xa inhibitors, including fondaparinux, rivaroxaban, and apixaban, work by inhibiting factor Xa, a crucial enzyme in the coagulation cascade. This inhibition prevents the conversion of prothrombin to thrombin, leading to reduced fibrin formation and producing rapid anticoagulation.

Anticoagulant Therapy for VTE Treatment

Patients with confirmed VTE should initially be treated with LMWH, UH, or an oral factor Xa inhibitor. Oral VKA therapy is another option, maintaining a therapeutic INR between 2.0 and 3.0. Active treatment should continue for at least three months.

Thrombolytic Therapy

Thrombolytic therapy involves the catheter-directed administration of drugs like urokinase or tissue plasminogen activator (tPA) to dissolve clots, reduce acute symptoms, improve deep venous flow, and decrease valvular reflux. It is indicated in cases of:

• Massive pulmonary embolism with hemodynamic instability
• Severe deep vein thrombosis with risk of limb gangrene
• Failure of conventional anticoagulation therapy

Surgical Management

Endovascular management is necessary for DVT when thrombolytic or anticoagulant therapy is contraindicated, the risk of pulmonary embolism is extreme, or venous drainage is severely compromised, risking permanent extremity damage. Key surgical procedures include:

• Thrombectomy, a procedure for severe deep vein thrombosis (DVT), mechanically removes blood clots from veins. It can be done through surgical thrombectomy, where an incision is made to open the vein and manually extract the clot, or percutaneous thrombectomy, which uses a catheter, mechanical devices, or aspiration for clot removal.
• Catheter-directed thrombolysis (CDT) delivers thrombolytic agents, such as tissue plasminogen activator (tPA), directly to clots under imaging guidance. Depending on the clot's size and location, a catheter is positioned at the clot site, and agents are infused over hours to days.
• A vena cava filter may be placed during thrombectomy or thrombolysis via a catheter through the femoral or jugular vein and positioned in the inferior vena cava. This filter traps large emboli and prevents pulmonary embolism.

By implementing these strategies and treatments, healthcare providers can effectively prevent and manage VTE, improving patient outcomes and reducing complications.