Pain comparison of unbuffered versus buffered lidocaine in local wound infiltration

The purpose of this study was to compare the pain of infiltration between unbuffered lidocaine and buffered lidocaine in a traumatic laceration. Solutions of unbuffered 1% lidocaine and buffered 1% lidocaine were randomly assigned to Site I or Site II of a single laceration for each subject, with the patient serving as self-control. Pain scores were recorded for each site, and an anesthetic preference was determined for each patient. It was found that buffered lidocaine had a preference ratio of 3.0 over unbuffered lidocaine (95% confidence interval, 1.86 to 4.84; P less than 0.0001). It was also found that Site I was preferred more often than Site II regardless of which medication was used. The conclusion is that buffered lidocaine is preferred over unbuffered lidocaine and that the order of injection is an important factor in trials that involve multiple sequential injections in the same patient.