D. C. Horne1, P. Georgoff1, M. A. Healy1, N. H. Osborne1 1University Of Michigan,Department Of Surgery,Ann Arbor, MI, USA
Introduction:
Venous thromboembolism (VTE) has been reported to occur in as much as 2-33% of patients undergoing major open vascular surgery. Despite this relatively high incidence, patients inconsistently receive chemoprophylaxis. The true incidence of VTE among patients receiving chemoprophylaxis is unknown. We sought to explore the effect of not only administration, but timing of administration of chemoprophylaxis on risk of VTE and post-operative bleeding among patients undergoing major open vascular surgery.
Methods:
Patients undergoing major open vascular surgery (defined as open abdominal aortic aneurysm repair, aorto-femoral bypass, mesenteric bypass) and infrainguinal bypass were identified from the Michigan Surgical Quality Collaborative (MSQC) between 2008 and 2012. Rates of VTE (deep venous thrombosis and/or pulmonary embolism) were compared between patients receiving and not receiving routine VTE chemoprophylaxis using univariate and multivariate statistics. Delay in the initiation of chemoprophylaxis was defined as initiation of therapy greater than 1 day following surgery. Among patients receiving VTE chemoprophylaxis, the effect of the timing of initiation of chemoprophylaxis upon development of VTE was determined using multivariate statistics. Post-operative complications were compared among all groups using univariate and multivariate analysis.
Results:
A total of 8776 patients underwent major open vascular surgery, including 1068 open AAA repairs, 958 aorto-femoral bypass and 6483 infrainguinal bypass procedures. The overall incidence of 30-day VTE was 1.4%, ranging from 0.99% among patients undergoing infrainguinal bypass and 2.62% among patients undergoing open abdominal procedures. Among all patients who received VTE chemoprophylaxis anytime during their admission, the rate of VTE was 1.45% as compared to 1.38% among those who did not receive chemoprophylaxis. However, accounting for the timing of chemoprophylaxis initiation, delay in the administration of VTE chemoprophylaxis was associated with a significantly higher risk of VTE (OR 3.92, p<0.01), controlling for pre-op risk of VTE. There was no increased risk of post-operative transfusion among patients receiving routine chemoprophylaxis compared those who did not (16.28% vs. 17.43%, p=0.197).
Conclusions:
Although patients undergoing major open vascular surgery appear to have a low risk of VTE at baseline, there is a significantly higher risk of developing VTE among patients who have a delay in the administration of VTE chemoprophylaxis. Bleeding complications were no higher among patients who routinely receive chemoprophylaxis. Surgeons should consider routinely initiating chemoprophylaxis in the early post-operative setting following major open vascular surgery.