Optimal concentration of epinephrine for vasoconstriction in neck surgery.

The addition of epinephrine to local anesthetics decreases bleeding, reduces systemic toxicity, and increases duration of action. However, epinephrine has significant side effects. Four concentrations of epinephrine were compared to determine the minimum concentration required for maximal vasoconstriction. Eighty-one subjects undergoing surgical procedures with general anesthesia were injected with 1% lidocaine containing varying concentrations of epinephrine. Blood flow measurements were then made at 1-minute intervals for 10 minutes using a laser Doppler flowmeter. There were no differences in blood flow reduction between epinephrine concentrations of 1:100,000, 1:200,000, and 1:400,000. However, epinephrine 1:800,000 provided significantly less vasoconstriction. We recommend using an epinephrine concentration of 1:200,000 or 1:400,000 to provide optimal initial hemostasis while minimizing potential side effects.