A STUDY OF THE EFFECTS OF EPINEPHRINE INFILTRATION ON DELAYED BLEEDING IN A RAT FLAP MODEL

Infiltrating the operative site prior to incision with an epinephrine solution will provide vasoconstriction and a dryer operative field. Ho wever, some surgeons fear that as the vasoconstrictive effects of the epinephrine subside, smaller vessels will rebleed and a hematoma may r esult. In this study, 51 rats were operated with two flaps. The ventra l pedicled flap, based on the inferior superficial epigastric arteries , and the McFarlane dorsal skin flap were utilized. The perimeter of a ll flaps was infiltrated with one of the following test infusions: (1) no infiltrate (control group), (2) 1% lidocaine hydrochloric acid (HC l), (3) 2% lidocaine HCl, (4) 1% lidocaine HCl and epinephrine 1:100,0 00, and (5) 0.5% lidocaine HCl and epinephrine 1:200,000. Flaps were r eplaced in their beds. Animals were sacrificed 24 hours postoperativel y. Flaps were raised at 26 hours and the coagulum weighed. No statisti cally significant difference was found between the weights of the coag ulum of the infiltrated flaps versus the noninfiltrated flaps. Statist ical power calculations on the main study flap yielded values greater than 80%. This suggests that the difference in delayed bleeding betwee n noninfiltrated flaps and flaps infiltrated with various combinations of lidocaine and epinephrine was insignificant.