Magnesium as an adjuvant for caudal analgesia in children.

BACKGROUND: There is a need for an adjuvant agent of caudal block that prolongs its duration and improves the analgesic efficacy to fasten functional recovery. Magnesium is an N-methyl-D-aspartate receptor antagonist that functions as an analgesic. This study was aimed to evaluate whether magnesium as an adjuvant for caudal block in children can improve postoperative analgesia and functional recovery. METHODS: Eighty children, 2-6 years of age, undergoing inguinal herniorrhaphy, were included in this prospective, randomized, double-blinded study. For caudal block, Group R received ropivacaine 1.5 mg·ml(-1), 1 ml·kg(-1) and Group RM received the same dose of ropivacaine mixed with 50 mg of magnesium. The Parents' Postoperative Pain Measure (PPPM) score, analgesic consumption, functional recovery, and adverse effects were evaluated at 6, 24, 48, and 72 h after surgery, as well as daily thereafter until the child showed full functional recovery. RESULTS: The PPPM score after hospital discharge was significantly lower for Group RM than for Group R at all times (P < 0.05). Children in Group RM required less fentanyl for rescue analgesia in the recovery area (16.2% vs 39.5%, P = 0.034) and less oral analgesics after discharge (20.5% vs 52.6%, P = 0.007). The time to return of normal functional activity was shorter in Group RM (P < 0.05). The incidence of adverse effects did not differ between groups. CONCLUSIONS: As an adjuvant for caudal analgesia, 50 mg magnesium provided superior quality of analgesia and faster return of normal functional activity than local anesthetic alone in children.ope