Preoperative cooling and warming of the donor site increase survival of skin flaps by the mechanism of ischaemic preconditioning: An experimental study in rats

Recent studies show that survival of skin flaps can be increased by ischaem ic preconditioning with repeated cycles of ischaemia and reperfusion before prolonged ischaemia or raising of the flap. In this study three cycles of cooling and warming of rat dorsal skin were used to regulate skin blood flo w and to induce three cycles of ischaemia and reperfusion. In 10 Sprague-Da wley rats three cycles of cooling (-18 degrees C ice pack) and warming (45 degrees C running water) were used to regulate skin blood flow before the f laps were raised. Caudally-based skin flaps 11 x 2 cm were then raised to t he left of the dorsal midline and sutured back. In the control group (n = 9 ) the flap was raised and sutured back without any treatment. Viability was assessed after seven days and the survival area calculated with planimetry . Viability increased from a mean (SD) of 61 (6)% in the control group to 7 7 (7)% in the experimental group (p<0.0001). This study shows that preopera tive cooling and warming of the donor site can be used to increase survival of skin flaps. The probable explanation is ischaemic preconditioning altho ugh the biochemical mechanism is unclear.