• M N Valvano and S Leffler.
• University of Vermont College of Medicine, Burlington, USA.
• Ann Emerg Med. 1996 Apr 1;27(4):490-2.

Study ObjectiveWe compared the efficacy, degree of discomfort, and time elapsed before anesthesia of digital block with a combination of 1% lidocaine/.25% bupivacaine and with .25% bupivacaine alone.MethodsWe carried out a randomized, double-blinded, prospective study in which subjects served as their own controls. The study group comprised 19 normal adult volunteer medical students and members of the community who volunteered to participate in a study evaluating "the use of commonly used local anesthetics by physicians." Two digital blocks were performed on each subject: one with a lidocaine/bupivacaine combination and one with bupivacaine alone. Two subjects did not complete the study; therefore 34 blocks were performed. Both the physicians and subjects were blinded to the anesthetic used for each block. Patients immediately rated the pain associated with each technique on a standard visual analog scale. Time elapsed before onset of anesthesia to pinprick was assessed and recorded after each block in 1-minute increments. We assessed efficacy on the basis of anesthesia to pinprick.ResultsMean visual analog scale pain scores were not different between the two types of blocks: 3 cm for lidocaine/bupivacaine and for bupivacaine alone (P = .76, Student t test; P = .44, Wilcoxon signed-rank test). Time elapsed before anesthesia to pinprick was not significantly different between the groups: mean, 5.0 minutes for lidocaine/bupivacaine and 5.35 minutes for bupivacaine alone (P = .75, Wilcoxon signed-rank test).ConclusionBupivacaine .25% digital block induces anesthesia in the same period of time and with equivalent pain of injection as a 1:1 lidocaine 1%/bupivacaine .25% combination. It is not necessary to use lidocaine/bupivacaine in an attempt to achieve faster onset of local anesthesia.

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