Does Topical Lidocaine Attenuate the Pain of Infiltration of Buffered Lidocaine?

Abstract

To determine whether topical lidocaine attenuates the pain of buffered lidocaine infiltration. This was a prospective, randomized, double-blind, placebo-controlled trial conducted at a university-based ED. The subjects were adults who had lacerations being repaired using local anesthesia. Two 0.5-mL injections of buffered lidocaine were given in a standardized manner. The first was given prior to application of topical study solution. The second was given on the opposite side of the laceration after topical application of study solution, which was 5 mL of either 2% lidocaine or saline placebo. The pain of each infiltration was measured using a visual analog pain scale. Pain scores were calculated and compared using a Wilcoxon test with significance defined as p < or = 0.05. A total of 54 subjects participated; 29 received lidocaine topically and 25 received placebo. The groups were similar with respect to age, gender, wound length, wound location, and initial pain score. Pain scores decreased by 11.6 +/- 18.6 mm for lidocaine and 10.9 +/- 20.9 mm for placebo (p > 0.5). The study had the power to detect a 15-mm pain score difference (alpha = 0.05 and beta = 0.20) on a 100-mm scale. Topical 2% lidocaine does not attenuate the pain of infiltration of buffered lidocaine more than does topical normal saline. Investigation of other topical anesthetics with and without epinephrine in conjunction with buffered lidocaine is warranted.