Venous thrombosis is a major cause of disability and death in all patient populations. Autopsy studies of hospitalized patients have demonstrated that massive pulmonary embolism (PE) is the cause of death in 5% to 10% of all hospital deaths and have suggested that two-thirds of all clinically important venous emboli are never recognized during life. In a population-based study, Anderson and colleagues estimated that 170 000 patients are treated for a clinically recognized initial episode of venous thromboembolism in US hospitals each year and that 90 000 patients are treated for recurrent disease. In addition, venous thromboembolism has been well documented as a common, serious, and, in some cases, fatal complication in the postoperative period. Despite the plethora of articles, books and courses on the prevention of this complication, physicians continue to underuse prophylactic regimens to prevent thromboembolic disease. Anderson and colleagues showed that 44% of university hospitals use prophylaxis compared to 19% of community hospitals. More striking was the fact that only 32% of the patients in this study who were at high risk for deep venous thrombosis (DVT) or PE received prophylaxis.

Pathophysiology

The pathophysiologic changes of stasis, intimate injury, and hypercoagulability predispose surgical patients to the development of DVT or PE. The supine position on the operating room table, the anatomic position of the extremities for some surgical procedures, and the effect of anesthesia all contribute to stasis during surgery. Venographic contrast studies have shown that the supine position on the operating table decreases venous return.