Fluorescence assessment of skin perfusion after oral fluorescein

This study evaluated oral ingestion as the route of fluorescein administration for fluorescence assessment of skin perfusion. In 10 anesthetized rats, dorsal pedicle flaps were raised to produce graded perfusion; then fluorescein (7.5 mg/kg) was administered via an oropharyngeal tube. Quantification of skin fluorescence, performed with the fiberoptic fluorometer 45 minutes after dye ingestion, delineated a significant difference between the perfusion of flap regions that remained viable and those that subsequently became dystrophic (p less than 0.05). The precision was equivalent to that previously reported after intravenous dye. In addition, the gradual delivery of dye after oral administration permitted monitoring of slope of uptake and time to peak. Each of these pharmacokinetic parameters delineated a significant difference between viable and nonviable sections. As measures of relative change in fluorescence, they are independent of skin color and thickness. This feature suggests that the oral route actually may improve the accuracy and reliability of the fluorescein test.