OBJECTIVETo observe the effect of local injection of recombinant hirudin on survival of skin flaps with venous congestion in a rabbit model.

METHODSEighteen healthy rabbits were enrolled and divided into heparin-treatment (HT), recombinant hirudin treatment (RHT) and control (C) groups according to the random number table, with 6 rabbits in each group. After intravenous anesthesia with 20 g/L pentobarbital sodium, model of skin flaps with venous congestion in the size of 6 cm × 3 cm was reproduced in the dorsal side of left ear of each rabbit, in which central artery of ear served as the only blood supply, and a pedicle of 1 cm in width including central vessel of ear and its accompanying nerves as the only venous return pathway. Each flap in RHT, HT, C groups was respectively given 1 mL recombinant hirudin (1 U), low-molecular-weight heparin (625 U), and isotonic saline via multi-point and homogenous injection, then they were sutured in site. Appearance and survival rate of the flaps were observed after operation. Specimens of the distal part of flaps were harvested for determination of thromboxane B2 (TXB2) on post operation day (POD) 1, 3, 5, 7. Data were processed with one-way analysis of variance and t test.

RESULTSRabbit model of skin flaps with venous congestion was reproduced successfully. Obvious hair loss was observed in completely necrotic parts of flap in each group. Obvious edema was observed in all flaps with venous congestion at distal site. The color of flaps in HT and RHT groups were lighter as compared with that in C group, and apparent hematoma of flap was observed in 1 rabbit of RHT group, 2 rabbits of HT group, 4 rabbits of C group on POD 1. The survival rate of flap in HT and RHT groups was respectively (92.3 ± 1.7)% and (94.8 ± 1.9)%, both higher than that in C group [(77.9 ± 1.2)%, F = 191.29, P < 0.05]. There was no statistical difference in survival rate of flap between HT group and RHT group (t = 2.75,P > 0.05). The content of TXB2 in HT and RHT groups on POD 3, 5 was respectively lower than that in C group (with t value from 6.68 to 30.55, P values all below 0.01), but there was no statistical difference between HT and RHT groups (with t value respectively 1.22, 6.44, P values all above 0.05).

CONCLUSIONSLocal injection of low-molecular-weight heparin or recombinant hirudin can significantly ameliorate venous congestion of skin flap in rabbit ear, and improve its survival rate.