Dynamic variations in blood flow as measured by laser Doppler velocimetry: a study in rat skin flaps.

Some of the measured variations of blood flow in skin flaps are reviewed. Ventral island skin flaps in rats are taken as an experimental model, and serial measurements using laser Doppler velocimetry have been made across the flaps for a period of up to 4 weeks postoperatively. The results demonstrate that areas of these flaps have periods of complete ischemia with no flow. These areas may survive. Conversely, apparently perfused areas later succumbed and became nonviable. The flow readings obtained are compared with fluorescence as a predictor of survival. The immediate and longer-term changes in flow across the length of these flaps are described. These findings are discussed with reference to the suggested methods of increasing the length of flap survival. The hypothesis of nonnutritive blood flow is also reassessed in the light of these findings.