Midazolam for caudal analgesia in children: comparison with caudal bupivacaine

Caudal analgesia is the most popular and commonly used regional anaesthesia technique for post operative analgesia in children undergoing lower limb, anoperineal and abdominal surgical procedures. It is commonly applied in all the paediatric patients undergoing the above mentioned surgery, as the goal of balanced anaesthesia is not only limited to intraoperative period but also good analgesia in post operative period. Many drugs like morphine, Pethidine, Neostigmine etc have been used as analgesic agent via the caudal route but not without their side effects. So Midazolam was used as an alternative drug as it may not be associated with the side effects encountered with the other drugs.

The objective of the study was to see the analgesic efficacy of caudal administration of Midazolam with comparison to Bupivacaine for post operative analgesia, and to observe for side effects if any.

This was a single blinded prospective observational study in children of age 1 to 6 years of ASA grade I undergoing elective hernia or hydrocoele surgery. The patients were allocated randomly into two groups (n=25) to receive caudal injection of either 0.25% Bupivacaine 1 ml/kg (group A) or Midazolam 50 microg/kg with normal saline 1 ml/kg (group B). In the post operative period heart rate, blood pressure, pain score, recovery to first analgesic time, total number of analgesics required in 24 hours and side effects if any were noted and analysed.

There were no significant differences in quality of pain relief, postoperative behaviour or analgesic requirements between the Midazolam group and the Bupivacaine group. Recovery to first analgesic time though was longer in the Bupivacaine group (9.65 hr) than Midazolam group (7.32 hr); it was statistically not significant (P= 0.9). Any of the side effects such as motor weakness, urinary retention, and respiratory depression were not observed in both the groups. However in both the groups, few of the patients had post operative vomiting.

We conclude that caudal Midazolam in a dose of 50 microg/kg provides equivalent analgesia to Bupivacaine 0.25%, when administered in a volume of 1 ml/kg for children undergoing unilateral inguinal herniotomy for hernia or high ligation of processus vaginalis for hydrocoele.