Monitoring free flap perfusion by serial fluorometry.

An efficient method to evaluate the patency of microvascular anastomoses and to predict flap viability is crucial when free flaps are used in reconstructive surgery. We report a study of 60 neurovascular island flaps in rats where the nutrient artery and/or vein were transected and anastomosed. Fluorescein dye was injected immediately after anastomosis, and the uptake and elimination of dye were quantified at 5-minute intervals with the fiberoptic perfusion fluorometer. Analysis of dye delivery clearly identified six hypofluorescent flaps presumed to be ischemic. In five of these flaps, revision was attempted. Three evidenced improved fluorescein uptake and elimination on reinjection of dye. These flaps survived, whereas the other two necrosed. Of the 54 flaps deemed patent after the first injection, two evidenced poor fluorescence on reinjection 3 hours later. These flaps necrosed and evidenced venous thrombosis (which probably occurred during the 3 hours between the first and second injections). Fiberoptic fluorometry can be employed to assess a free flap immediately after vascular anastomosis and throughout the critical hours postoperatively. Assessment of uptake and elimination after single or serial injections reflects flap perfusion and predicts viability with a high degree of accuracy.