**6. Trauma**

186 Venous Thrombosis – Principles and Practice

thrombosis (45-46). In those studies, the rate of asymptomatic thrombosis was 5%–7% after prolonged prophylaxis. Although the majority of asymptomatic DVT is not clinically significant, there is an association between asymptomatic DVT and the subsequent development of symptomatic VTE (47). In most studies, the ratio of asymptomatic DVT to symptomatic VTE ranges from 5:1 to 10:1. If a ratio of 10:1 is applied, the incidence of symptomatic DVT is approximately 0.5%–0.7% after prolonged thromboprophylaxis (4 weeks), similar to that found in the present study (0.63%). It shows the comparable incidence with that of Western countries, although in the present study thromboprophylaxis was administered only to high-risk patients and the treatment was of much shorter duration

Venous thromboembolism is a common complication in cancer patients due to the hypercoagulable state induced by changes in the coagulation system (48). A prothrombotic state is present in many cancer patients as a result of an increase in procoagulants, such as tissue factor, cancer procoagulant, and factor VIIa, and hypercoaguability increases as the cancer progresses (49,50). Patients with metastatic cancers are at an increased risk of VTE. Several studies have shown a direct association between cancer stage and thrombosis risk. Recent studies showed that a higher initial cancer stage was a strong independent risk factor for developing VTE within the first year after diagnosis of cancer (51). In the Korean study, multivariate analysis showed metastatic colorectal cancer (stage IV) was found a predictor of VTE. Moreover, advanced colorectal cancer (stage III, IV) was also a predictor of VTE, and patients with advanced cancer were twice as likely to be diagnosed with VTE as

Renal clearance is the primary mode of elimination for several anticoagulants, including LMWH, fondaparinux, and the new oral factor Xa and Ha inhibitors. Therefore, with reduced renal function, these drugs may accumulate and may increase the risk of bleeding, particularly in elderly patients and those at high risk for bleeding (53). The relationship between renal impairment and drug accumulation for the various LMWHs appears to be variable and may be related to the chain length distribution of the different LMWH preparations (54). Two recent studies in hospitalized patients, the majority of whom were critically ill and had creatinine clearances less than 30 mL/min, have shown no bioaccumulation of dalteparin 5000 U once daily based on serial anti-factor Xa levels (55,56). Therefore, we do not reduce the prophylaxis dose of dalteparin in patients with renal insufficiency. In patients receiving intermittent hemodialy-sis, we suggest that the LMWH be administered after the dialysis session. With enoxaparin thromboprophylaxis, we suggest that 30 mg once daily be used. We also suggest that fondaparinux, rivaroxaban and dabigatran be avoided unless future evidence demonstrates that these agents can be used

**5. Concomitant use of regional anesthesia techniques and anticoagulant** 

Neuraxial blockade (spinal or epidural anesthesia and continuous epidural analgesia) results in a significant reduction in cardiopulmonary morbidity compared with general anesthesia and narcotic-based systemic analgesia, as well as better pain control and patient

(median 3 days) and at a lower dose than that reported in those other studies.

patients with less-advanced cancer (52).

**4. Anticoagulant use in renal insufficiency** 

safely in patients with severe renal insufficiency.

**prophylaxis** 

Deep venous thrombosis DVT and pulmonary embolism are among the most common preventable sources of mortality and morbidity in trauma patients treated in intensive care units. In various studies, DVT and PE have been demonstrated to range from 6%to 40% and from2%to 22%, respectively, in patients with serious spinal/head trauma (5, 6, 60-62). Knudson et al. and Geerts et al. reported that in trauma patients other than the ones with head trauma LMWH was better than unfractionated heparin for DVT prophylaxis (61,62). Vanek, with a metaanalysis, showed that intermittent pneumatic compression (IPC) decreased the relative risk of DVT by 62%, 47%, and 48% compared to placebo, highpressure stockings, and LMWH, respectively (63). Norwood et al. reported that enoxaparin for DVT prophylaxis in patients with acute brain injury having an Abbreviated Injury Score of > 3 did not increase the morbidity (64). Early use of LMWH for DVT prophylaxis in the presence of intraabdominal solid organ injury (liver, spleen, kidney) may also be safe (6, 61). A properly placed and managed intermittent pneumatic compression device could provide thromboprophylaxis of comparable efficacy to that of LMWH, in patients with moderate and severe injury (65).

Approaching Venous Thrombosis in General Surgery Patients 189

survival, with encouraging but inconclusive results (74). Given that anticoagulant prophylaxis could have dual benefits for patients with cancer reducing VTE and prolonging survival it is vital to pursue well-designed clinical trials of thromboprophylaxis focusing on

An informative summary from American College of Chest Physicians Evidence-Based Clinical Practice Prevention of Venous Thromboembolism Guidelines (8th Edition)(3).

Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh






Grade 2 suggestions imply that individual patient values may lead to different choices

survival(75).

**9. Appendix** 

**10. Guyatt grading(76)** 

risks, burden, and costs.

**11. General surgery** 

(Grade 1C).

considered (Grade 2A).

**12. Cancer patients** 

fondaparinux (each Grade 1A).

daily, or fondaparinux (each Grade 1A).
