Alkalinizing local anesthetic does not decrease pain during injection for dorsal penile nerve block

To evaluate whether alkalizing local anesthetic with sodium bicarbonate reduces pain related to infiltration of local anesthetic during dorsal penile nerve block for circumcision.

Prospective, randomized, double-blind, controlled study.

E. Wolfson Medical Center, Holon, Israel.

144 patients aged 15 to 54 years (mean +/- SD = 22.7 +/- 8.8 years), randomized before the block into four groups of 36 patients each.

Group A (control) received a standard solution of 1 mg/kg lidocaine 2% mixed with 0.5 mg/kg bupivacaine 0.5% without epinephrine (pH = 6.3). Patients in Group B, Group C, and Group D received this mixture added with 8.4% sodium bicarbonate for a mean final pH of 6.90, 7.16, and 7.43, respectively. Penile block was performed using a 23-gauge needle by an anesthetist who was blinded to the pH of the solution.

Patients were questioned regarding pain suffered during injection of the anesthetic solutions by another physicians who also was blinded to the drug used. Pain was rated by a previously reported subjective pain scale. Mean pain scales were 2.0 +/- 0.17, 2.3 +/- 0.15, 2.2 +/- 0.16, and 1.94 +/- 0.15 for Groups A to D, respectively. The differences between these results were not statistically significant.

Alkalinizing the acidic local anesthetic solution by sodium bicarbonate does not decrease pain related to infiltration during penile nerve block for circumcision.