ABSTRACT
A number of variables place patients at increased risk for venous thromboembolism and hence pulmonary emboli (Table 12.1).
• Surgery and trauma. Prolonged venous stasis carries the highest risk; causes include venous valvular insufficiency, right heart failure, and prolonged immobility. Type and length of surgery are determinants of deep venous thrombosis (DVT). Abdominal operations requiring general anesthesia for greater than 2 h increase risk for DVT. The risk associated with surgery is higher with pelvic and leg procedures, hip replacement, hip fracture repair or knee replacement5 (Table 12.2). Measures such as perioperative prophylactic therapy with heparin, low molecular weight heparin, or mechanical techniques such as compression stockings or intermittent pneumatic compression can lower the risk. The risk of DVT in trauma patients is related to prolonged immobilization, severe head trauma, paralysis, pelvic and lower extremity fractures, venous trauma, shock and multiple transfusions, with the risk greatest in the first 2 weeks postinjury6. With spinal cord injury, the incidence of venous thromboembolism (VTE) is approximately 4% and that of PE about 5%.
