For surgical patients, pneumatic compression devices are most effective when applied either intraoperatively or as soon as feasible postoperatively and worn continuously until the patient is fully ambulatory. Anticoagulation is contraindicated in patients with intracranial bleeding, incomplete spinal cord injury associated with a hematoma at the area of injury, uncontrolled bleeding, and uncorrected coagulation disorders. Achieving rapid, therapeutic anticoagulation with heparin is important because even small recurrences of thrombus formation can be life-threatening in patients with poor cardiopulmonary reserve. Unless the risk of bleeding is high, heparin should be administered immediately on suspicion of VTE, even before diagnostic studies are performed. Heparin prevents thrombosis by activating antithrombin III, a naturally occurring inhibitor of several blood clotting factors.
Traditional heparin is known as unfractionated heparin.
LDUH has a short half-life and duration of action, requiring continuous intravenous infusion or multiple subcutaneous injections. Heparin therapy also has been associated with bleeding and heparin-induced thrombocytopenia. The thrombus that causes such an occlusion is a white thrombus, comprised primarily of clumped masses of platelets. Its bioavailability is more than 90 percent, it has a longer half life, and is less likely to cause bleeding and thrombocytopenia. Recent studies show that selected patients with proximal venous thrombosis can be treated at home with LMWH and warfarin.