We used the rat medial gastrocnemius free flap, based on a pedicle of the femoral artery and vein, in order to test the tolerance of skeletal muscle to cold ischemia‐reperfusion (IR) injury, and to determine whether tolerance can be enhanced by pre‐ischemic perfusion with tissue/organ preservation solutions.
Muscle flaps (n = 6 per group) were subjected to variable periods of cold storage (0, 1, 2, 3, or 4 days) and 24‐h normothermic reperfusion. Muscle viability, as determined by nitroblue tetrazolium (NBT) histochemical staining of viable mitochondria and supported by histological examination, was 100%, 26%, 11%, 4%, and 1%, respectively. Using 24‐h cold storage/24‐h reperfusion as the experimental conditions, groups of muscle flaps (n = 5 per group) were perfused immediately before cold storage with either modified, colloid‐free University of Wisconsin (UW) solution, a solution described by Kohout et al. (Br J Plast Surg 1995;48:132–144) or normal saline. Perfusion with modified UW solution or Kohout's solution increased survival to 33% (P < 0.05) and 28% (not statistically significant), respectively, compared with the 19% viability of separate groups of nonperfused or saline‐perfused controls. These findings indicate that cold‐stored skeletal muscle is highly susceptible to cold IR injury and that the viability can be increased by prior perfusion with a tissue preservation solution such as modified UW solution. © 2000 Wiley‐Liss, Inc. MICROSURGERY 20:343–349 2000