Wang HZ, Wang LY, Liang HH, et al. - A prospective randomized trial was designed to evaluate the impact of caudal ketamine on minimum local anesthetic concentration of ropivacaine in children. Researchers randomized 169 children into 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 endpoint included the minimum local anesthetic concentration (MLAC) values of ropivacaine with/without ketamine for caudal block. The results of this study demonstrate that adding caudal ketamine to ropivacaine prolong the duration of post-operative analgesia; nevertheless, it does not reduce the MLAC of caudal ropivacaine for intra-operative analgesia in children.