Is surface cooling effective for tissue preservation in free-flap surgery?

Effective tissue cooling can extend the period of safe ischemia. To determine whether the technique of surface cooling could produce an effectively low core temperature (4 degrees to 10 degrees C) in the flap core in a reasonable amount of time, bovine muscle/subcutaneous fat flaps, weighing 400, 800, and 2000 g, were brought to 37 degrees C and then surface cooled. Temperatures were then recorded every 5 min. All flaps were able to attain 4 degrees C in the core; the average times for the 400, 800, and 2000 g flaps to reach 4 degrees C were 136, 153, and 194 min, respectively. Although a clear inverse relationship existed between flap weight and effectiveness of core cooling, even relatively large flaps (2000 g) could still achieve sufficiently low core temperatures from surface cooling well within tolerable warm ischemia time. Concern for ischemia time generally should not interfere with efficient, orderly, free-flap surgery.