Parents are increasingly asking for safe and effective pain relief for their infants during circumcision. Use of a dorsal penile nerve block with lidocaine is believed to provide adequate pain relief, but many physicians do not use it, concerned that stinging from lidocaine at the injection site could add to the stress of the procedure. The time associated with administering the anesthetic may also be a factor. Buffered lidocaine has been shown to decease stinging and speed the anesthetic effect. Newton and colleagues compared the effectiveness of plain lidocaine with that of buffered lidocaine in reducing pain experienced during the injection and in providing pain relief during the procedure.

All healthy newborn boys circumcised at a large Midwestern hospital were eligible for the two-year study. Infants were randomized to receive 1 percent lidocaine, either as a simple solution or buffered with sodium bicarbonate. No other comfort measures were given. The circumcisions were performed using standard technique, and involved personnel knew which anesthetic was used on each infant. Heart rate and oxygen saturation were monitored continuously, and the infants were evaluated three times during the procedure using a behavioral scale based on levels of arousal.

A total of 194 infants were enrolled in the study, 92 in the plain lidocaine group and 102 in the buffered lidocaine group. No significant differences in heart rate, oxygen saturation, arousal score or general clinical observations were noted between groups. Minor bleeding occurred in a small percentage of infants in each group; otherwise, there were no complications.

The authors conclude that both solutions provided safe and effective anesthesia for the procedure. Both solutions appeared to have a similar onset of action and provided a comparable level of pain relief. The addition of a buffering agent to lidocaine did not influence anesthetic effectiveness, although other studies suggest that the rate of infiltration may be a significant factor. Less pain may be experienced when the anesthetic agent is infiltrated slowly.