Abstract
General Considerations
Despite contemporary developments in pharmacology and biomedical engineering, venous thromboembolism (VTE) is not fully preventable and thus still remains a serious complication of trauma, surgery, and medical conditions. Current and previous guidelines recommend risk stratification to tailor implementation of prophylactic methods so that combined modalities are recommended based on supportive evidence in high-risk patients, although cost and potential adverse events make them less effective for low-risk groups. The reason for the increased efficacy of combined modalities is based on the multifactorial etiology of VTE as first described by Rudolph Virchow in the 19th century. 1 Physical methods reduce venous stasis while pharmacological methods affect hypercoagulopathy. The fact that combined modalities are more effective than single modalities was first shown by Borow in 1983 followed by several studies supporting this concept. 2 Although elastic stockings are effective in reducing further VTE rates achieved by perioperative antithrombotic prophylactic pharmacotherapy, as indicated in several places in this document, most modern studies have evaluated the role of the combination of intermittent pneumatic compression (IPC) with pharmacological methods, and this will be the focus of this section.
A recent Cochrane review evaluated the efficacy of combined modalities (IPC) and pharmacological prophylaxis: treatment group) against single modalities alone (control group) to prevent pulmonary embolism (PE) and deep vein thrombosis (DVT) in patients at high risk of VTE. 3 A total of 11 studies that included 7431 patients were identified, of which 6 were randomized-controlled trials (RCTs). The studies evaluated orthopedic patients (n = 6), urology patients (n = 2), and general surgery, cardiothoracic, and gynecology patients (n = 3). Compared to compression alone, combined modalities significantly reduced the incidence of both symptomatic PE (from about 3% to 1%; odds ratio [OR] 0.39; 95% confidence interval [CI] 0.25-0.63) and DVT (from about 4% to 1%; OR 0.43; 95% CI 0.24-0.76). Compared to pharmacological prophylaxis alone, combined modalities significantly reduced the incidence of DVT (from 4.21% to 0.65%; OR 0.16; 95% CI 0.07-0.34). The studies were underpowered with regard to PE.
The comparison of compression plus pharmacological prophylaxis versus compression plus aspirin showed a nonsignificant reduction in PE and DVT in favor of the former group. Repeat analysis restricted to the RCT confirmed the above findings.
The additive role of mechanical and pharmacological modalities suggests that venous stasis and hypercoagulopathy are independent pathogenetic risk factors. The IPC reduces venous stasis by producing active flow enhancement4,5 and also increases tissue factor pathway inhibitor plasma levels. 6
The results of the above meta-analyses endorse a recommendation that high-risk patients should receive multimodal prophylaxis. Although most patients who used combined modalities in the studies reviewed were considered to be at high risk of developing VTE, future studies on this topic should use the most recent and validated criteria to define the high-risk patient.
Recommendations
Combined modalities (IPC and pharmacological prophylaxis) should be considered in all high-risk surgical patients (level of evidence: high). Individual recommendations for specific groups of patients appear in the relevant sections of this document.