Randomized double-blind comparison of duration of anesthesia among three commonly used agents in digital nerve block.

BACKGROUND: Three local anesthetics are commonly used for digital nerve block: 2% lidocaine with 1:100,000 epinephrine, 2% lidocaine, and 0.5% bupivacaine. The authors have not identified a study that has compared these three agents in digital nerve block in a randomized fashion. The goal of this study was to determine which of the three agents provided the longest duration of digital nerve blockade.

METHODS: Thirty volunteers had the long finger of each hand along with one of their small fingers anesthetized with one of the above agents, respectively. The local anesthetic agent to be used in each finger was randomized. A double-blind design was used. Volunteers reported the time that each of their fingers returned to normal sensation at the tip. An analysis of variance was used to detect significant differences among the three groups, and subsequent pair-wise comparisons were performed using post hoc Tukey tests.

RESULTS: The mean duration of anesthesia was as follows: 0.5% bupivacaine, 24.9 hours; 2% lidocaine with epinephrine (1:100,000), 10.4 hours; and 2% lidocaine, 4.9 hours. In both the Bonferroni and Tukey tests, all three agents provided significantly different durations of digital nerve blockade (p = 0.01).

CONCLUSIONS: At an average of 24.9 hours, bupivacaine (0.5%) provides a significantly longer digital anesthesia time than the average 10.4 hours achieved by 2% lidocaine with epinephrine (1:100,000), which in turn provides twice as long an anesthesia time as 2% lidocaine (average, 4.9 hours).