Nutrient blood flow in delayed axial pattern skin flaps in pigs.

Blood flow was investigated in 112 skin flaps (84 delayed and 28 undelayed) in 28 pigs. The flow was significantly (P less than 0.001) increased over the control flow with increasing delay intervals, reaching the greatest flow at one week after the delay (paralleling the increase in tissue survival). This increased blood flow persisted after definitive flap raising. The circulatory adjustments within the first week of the delay constitute the delay phenomenon, and they determine the ultimate viability of the skin flap in this model.