Protective effects of activated protein C (APC) on free groin flaps after secondary venous stasis in the rat model

BACKGROUND: The goal of this study was to determine whether the focused delivery of APC by rinsing of free adipocutaneous groin flaps shows protective effects on flap survival following a fatal secondary venous stasis in a rat model. METHODS: 36 Sprague Dawley rats were randomized to three groups and free microvascular groin flaps were transplanted to the neck in each animal. 20 hours postoperatively the flap pedicle was re-explored and the distal stump of the flap artery was catheterised. Animals in group I (n = 12) remained untreated, whereas animals of group II were treated with 1 ml of Ringer's solution. Those in group III received 1 ml of APC (2 mg/kg). Afterwards the flap vein was clamped for 35 minutes. The skin of the flaps and the native contralateral groin was examined by intravital video microscopy using FITC-Dextran and CFDA-SE-labelled thrombocytes. RESULTS: APC-pretreatment significantly increased the functional capillary density (FCD) of the flaps. Flap viability was 8% in group I (n = 1/12), 9% in group II (n = 1/11) and 60% in group III (n = 6/10), respectively. No partial flap loss was detected. CONCLUSIONS: The focused delivery of APC resulted in significantly improved flap salvage.