No correlation between activated protein C resistance and free flap failures in 100 consecutive patients

This study evaluates whether thrombophilic disorders contribute to failures in microvascular surgery. A recently discovered condition is focused on, i.e., activated protein C resistance, which is a highly prevalent functional defect of a crucial endogenous anticoagulant system--the protein C anticoagulant pathway (up to 15 percent of Caucasians affected). One hundred consecutive patients were operated on with 103 free tissue transfers during a 2.5-year period, all of which received perioperative intravenous anticoagulation, principally based on dextran (1 liter) and a heparin bolus at vascular reperfusion (80 to 100 IU/kg). The patients underwent extensive laboratory analysis with respect to conditions predisposing for thrombosis. Eleven patients were found to be activated protein C resistant, and one patient had congenital protein S deficiency. There were six total and five partial flap losses, which, however, in only one case coincided with the presence of a thrombophilic disorder (activated protein C resistance). By contrast, a substantial portion of flap necroses could be related to nonconstitutional factors (for example, pedicle kinking). It is concluded that routine screening for hypercoagulable states such as activated protein C resistance is not necessary in microvascular surgery.