Sixteen healthy adult female patients scheduled for elective abdominal hysterectomy were divided into two groups, and the venous plasma concentrations of lidocaine for both groups were measured at 5, 10, 15, 30, 45 and 60 minutes after an
epidural
injection of 2% lidocaine 500mg. Group 1 received plain lidocaine, and group 2 received lidocaine with 5μg/ml epinephrine.
We observed that the mean measured plasma concentration of lidocaine in group 2 was significantly lower than in group 1 over the entire studied time course(P<0.05). The addition of epinephrine to the lidocaine solution reduced the peak plasma
concentrations by 49%(from 7.76 to 3.97); however, this did no prolong the times at which the peak concentrations were reached. We hypothesized that these results may have been caused by some reduced epidural blood flow which have decreased the
amount
of lidocaine absorption
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