Epinephrine's effect in varying concentrations on the end artery organ in an animal model.

OBJECTIVE To determine the concentration of epinephrine that causes end artery necrosis and ischemia. STUDY DESIGN An experimental study. PLACE AND DURATION OF STUDY Animal Laboratory of Khordad Hospital, Tehran, Iran, from September 2007 to June 2008. METHODOLOGY This study was done on 54 ear flaps from 9 rabbits [9 (rabbits) x2 (ears) x3 (splits) =54] divided into three groups of 18 ear flaps each. Nine of the ear flaps were randomized as control and nine of them were randomized as study group. The different concentrations of epinephrine and lidocaine 1% were injected in study groups but only 1% lidocaine was injected in control groups. Study group 1 received 1/200000, group 2 received 1/100000 and group 3 received 1/500000 concentration of epinephrine respectively. RESULTS There was no evidence of necrosis in the control and study groups 1 and 2. However, 4 out of 9 of the ear flaps showed clear evidence of tissue necrosis in group 3. CONCLUSION Injecting epinephrine in 1/200000 and 1/100000 concentrations had no side effect for the end artery of the rabbit ear flaps, but 1/50000 concentration is shown that it can cause tissue necrosis. Further studies need to be done in order to find out the effects of epinephrine with the same concentrations on the human end artery.