Cutaneous blood-flow patterns in free flaps determined by laser Doppler flowmetry

Accurate monitoring of tissue perfusion in microvascular surgery is paramount to flap survival. Many methods have been proposed for monitoring of flaps, but none have achieved widespread acceptance. The laser Doppler has been shown to be beneficial in monitoring flap perfusion. Trends have been noted in laser Doppler measurements over time in free TRAM, free latissimus dorsi, and free iliac-crest osteomyocutaneous flaps. TRAM flaps demonstrated a slow increase in the laser Doppler index (LDI), with a peak increase in skin blood flow of over 600 percent at 52 to 80 hr postoperatively (LDI 6.77 +/- 3.51), and then a gradual decline to previous baseline. Latissimus dorsi flaps also demonstrated a slow increase until about 80 hr postoperatively (LDI 9.8 +/- 10.65), indicating an increase in skin blood flow of almost 900 percent. Iliac-crest osteomyocutaneous free flaps had a slow increase in blood flow until approximately 70 hr postoperatively, when the LDI (5.5) increased, representing an increase in skin blood flow of over 500 percent. These changes in skin blood flow over time, seen with continuous laser Doppler measurements, depict the dynamic nature of skin blood flow and allow predictive patterns to be established, instead of single normal values, by which to gauge adequate flap perfusion.