Background
Caudal ketamine has been shown to provide an effective and prolonged post-operative analgesia with few adverse effects. However, the effect of caudal ketamine on the efficacy of ropivacaine for intra-operative analgesia is unclear.
Methods
One hundred and sixty-nine children were randomized to five groups: Group C (caudal ropivacaine only), Group K0.25 (caudal ropivacaine plus 0.25 mg/kg ketamine), Group K0.5 (caudal ropivacaine plus 0.5 mg/kg ketamine), Group K0.75 (caudal ropivacaine plus 0.75 mg/kg ketamine), and Group K1.0 (caudal ropivacaine plus 1.0 mg/kg ketamine). The primary outcome was the minimum local anesthetic concentration (MLAC) of ropivacaine with/without ketamine for caudal block.
Results
The MLAC values of ropivacaine were 0.128% (0.028%) in the control group, 0.112% (0.021%) in Group K0.25, 0.112% (0.018%) in Group K0.5, 0.110% (0.019%) in Group K0.75, and 0.110% (0.020%) in Group K1.0. There were no significant differences among the five groups for the MLAC values (p=0.11). During the post-operative period the mean durations of analgesia were 270, 381, 430, 494, and 591 min in the control, K0.25, K0. 5, K0.75, and K1.0 groups respectively, which shown significant differences among the five groups (p<0.05).
Conclusions
Adding caudal ketamine to ropivacaine prolong the duration of post-operative analgesia; however, it does not decrease the MLAC of caudal ropivacaine for intra-operative analgesia in children.