Quantitation of the Postoperative Vascular Response in Four Dorsal Bipedicle Flaps in the Rat

The rodent bipedicle flap has been used in numerous permutations as a model of ischemia and to generate a compromised tissue bed. In this study 24 rats were used to investigate skin perfusion over time along the length of 4 distinct bipedicle flap designs-2 oriented cranial-caudally and 2 transverse. Traditional rectangular flaps were evaluated as well as unique elliptical geometries designed to maximize the area of the resulting ischemic bed. Perfusion was assessed by scanning laser Doppler and intravascular dye penetration. In all models, an initially ischemic bed as measured by Doppler reestablished basal perfusion rates within 2-4 days and went on to produce a hyperemic bed with perfusion levels well above baseline. Reduced perfusion areas visualized by fluorescein dye penetration completely resolved in 55% of flaps within 2 days, and 68% within 4 days. This study underscores the difficulty in developing a representative model of chronic ischemia in young healthy rats as well as their remarkable ability to recover from acute surgical insults.