The effect of delay on flap survival in an irradiated field

Chronic radiation skin injury without ulceration was induced in rats by administering either 3000 or 5000 rads in staged doses. Either 4 or 8 months later, McFarlane et al. dorsal flaps were elevated, with half being delayed and half non-delayed. Measurements showed that flap survival in irradiated skin was significantly increased by delay [approximately two of four experimental groups (4 months, 5000 rads; and 8 months, 3000 rads)]; flap survival was increased with borderline significance in a third experimental group (8 months, 5000 rads). These data indicate that flap survival can be increased by delay in an irradiated field. The presence of the vascular delay phenomenon suggests that microvascular occlusion alone cannot account for radiation-induced complications in skin.