THe hazards of injecting local anesthetic solutions with epinephrine into flaps: experimental study.

In a study using paired longitudinal flaps on the back of the rat, we found evidence to support the findings of previous investigators regarding the toxic effects of injecting local anesthetic solutions containing epinephrine into delayed flaps. Epinephrine concentrations of 1:200,000 and 1:400,000 were demonstrated to significantly increase losses in these flaps. Epinephrine concentrations of 1:100,000, 1:200,000, and 1:400,000 were not demonstrated to be harmful to undelayed flaps, in the dosages used.