Slow injection of local anaesthetic will decrease pain during dorsal penile nerve block

Purpose: To evaluate whether a very slow injection of local anaesthetics during dorsal penile nerve block for circumcision causes less pain than a more rapid injection. Methods: In a prospective, double-blind, randomized study, 75 patients aged 15 to 53 yr (mean±SD=22±8.4 yr) were randomized into two groups. A solution of 2% lidocaine, 1 mg·kg^-1, and 0.5% bupivacaine, 0.5 mg·kg^-1 without epinephrine to a maximum dose of 10 ml was injected using either a very slow rate (injection time 100 to 150 s, Group A) or a faster rate (injection time 40 to 80 s, Group B). Patients were questioned regarding pain by a physician who was blinded to the mode of therapy. Pain was rated as 1) mild (negligible), 2) moderate (non-negligible, but easily endurable), 3) intense (but endurable) and 4) total refusal to continue. Results: A significant pain score difference was found between Groups A and B (median=1 vs. 2, P=0.0006) as well as a significant correlation between pain score and the rate of infiltration (r(s)= -0.394, P<0.0001). Conclusions: Slow injection is an important factor in reducing pain during penile block.