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

STUDY OBJECTIVE: To evaluate whether alkalizing local anesthetic with sodium bicarbonate reduces pain related to infiltration of local anesthetic during dorsal penile nerve block for circumcision. DESIGN: Prospective, randomized, double-blind, controlled study. SETTING: E. Wolfson Medical Center, Holon, Israel. PATIENTS: 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. INTERVENTIONS: 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. MEASUREMENTS AND MAIN RESULTS: 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. CONCLUSION: Alkalinizing the acidic local anesthetic solution by sodium bicarbonate does not decrease pain related to infiltration during penile nerve block for circumcision.