A comparison of two different doses of bupivacaine in caudal anesthesia for neonatal circumcision. A randomized clinical trial.

Background: We aimed to compare the analgesia quality of caudal block of low volume, high concentration bupivacaine to the conventionally used volumes and concentrations of the drug in neonates undergoing circumcision with sole caudal anesthesia.

Methods: Fifty neonates, undergoing circumcision were randomly assigned to low volume high concentration (group LVHC, n=25) and control groups (group C, n=25). Both groups received a caudal injection: Group LVHC 0.5 ml/kg bupivacaine 0.375% (1.875 mg/kg) and group C 1 ml/ kg bupivacaine 0.25% (2.5 mg/kg). Hemodynamic parameters, block onsets and analgesia periods were compared among the groups. Pain scores were evaluated hourly for 3 hours postoperatively with NIPS (neonatal infant pain score). Statistical analyses were performed with Student's t-test for continuous variables. X(2) and Mann-Whitney U-tests were used for nominal and/or categorical variables.

Results: Demographic, hemodynamic data, block onset time (group LVHC and C values were 4.9 +/- 1 vs 5.2 +/- 2 mins, respectively; p=0.53) was similar and postoperative median NIPS (a median value of 0 at postoperative 1, 2, and 3. hours) were identical among the groups (p=0.7, p=0.9, p=1). None of the neonates required additional analgesic for the first 24 hours following the surgery; therefore postoperative analgesic requirement was similar among the groups (p>0.1).

Conclusions: Low volume high concentration caudal bupivacaine provided a similar perioperative analgesia quality, time and safety profile compared to conventional bupivacaine doses in awake neonates undergoing circumcision. Low volume, high concentration bupivacaine may be used to reduce the risk of local anesthetic toxicity in outpatient neonates.