The effect of injection speed on the pain of lidocaine infiltration.

Abstract

To determine whether reducing the speed of injection is effective in reducing injection pain for buffered and unbuffered lidocaine solutions. A prospective, single-blind, randomized, crossover, laboratory study was performed. Adult volunteers were recruited from ED staff at an urban teaching hospital to serve as subjects. Twenty-nine subjects each received 4 1-mL injections into the dorsum of the hands. Each subject received fast and slow injections of buffered and unbuffered lidocaine. Subjects rated the pain of each injection on a 100-mm visual analog scale (VAS). Mean pain scores for each intervention were compared using analysis of variance. The mean pain VAS score for fast injection of buffered lidocaine was 14.1 mm. For slow buffered injection, the mean pain score was 11.4 mm (p = 0.98). For unbuffered lidocaine, the means were 28.7 mm for fast injection and 22.2 mm for slow injection (p = 0.40). Reducing injection speed did not produce a statistically significant change in injection pain for either buffered or unbuffered solutions.