Analgesic effectiveness of caudal levobupivacaine and ketamine

Abstract

Background: Ketamine is used increasingly in paediatric anaesthetic practice to prolong the action of a caudal block. This study was designed to determine if adding S(+)-ketamine 0.5 mg kg(-1) allows a lower concentration of levobupivacaine to be used for caudal anaesthesia without loss of clinical effectiveness.

Methods: One hundred and sixty-four children (ASA I or II) aged 3 months-6 yr were randomly allocated to receive 1 ml kg(-1) of levobupivacaine 0.15% with 0.5 mg kg(-1) S(+)-ketamine (Group 1), levobupivacaine 0.175% with 0.5 mg kg(-1) S(+)-ketamine (Group 2), or levobupivacaine 0.2% (Group 3) by the caudal route. Pain, motor block, sedation, and requirement for postoperative analgesia were assessed up to 6 h after operation.

Results: There was no significant difference between the groups in effectiveness at first surgical incision. Significantly lower analgesic requirements were reported in Group 2 compared with Group 3 at wakeup, 180 and 360 min after operation. Time to first rescue analgesia was longer in Group 2 compared with Group 1 or 3. Kaplan-Meier survival analysis of analgesia free time demonstrated a significant advantage of Group 2 over Groups 1 and 3 (log rank P=0.05). The incidence of postoperative motor block was not significantly different between the groups. No excess sedation or dysphoric reactions were observed in the ketamine groups.

Conclusions: The addition of 0.5 mg kg(-1) S(+)-ketamine to levobupivacaine 0.175% for caudal analgesia for lower abdominal and urological surgery is significantly more effective in providing postoperative analgesia than levobupivacaine 0.15% with 0.5 mg kg(-1) S(+)-ketamine or levobupivacaine 0.2%.