Use of urokinase during secondary ischemia in experimental skin flaps.

The ability of urokinase to salvage experimental flaps after a secondary ischemic insult was investigated in a rat model. Unilateral abdominal island skin flaps based on the superficial inferior epigastric vessels were raised and subjected to either 4 or 6 hours of primary ischemia followed by 12 hours of reperfusion and varying lengths of secondary ischemia. At the conclusion of secondary ischemia, the flaps were perfused with either lactated Ringer's solution or urokinase. One group of flaps served as a control and received no postischemic perfusion washout. The secondary critical ischemia time at which 50% of the flaps failed clinically was greater for flaps perfused with urokinase. Furthermore, the survival rates for all flaps perfused with urokinase were significantly greater than either control flaps or flaps perfused with lactated Ringer's solution (p < 0.05). Flap survival decreased significantly in all groups with increasing primary and/or secondary ischemia time (p < 0.05).