Abstract: Background：The use of dezocine, a new opioid agonistantagonist, for postoperative analgesia in children is poorly reported, and there is no accepted reference dose for its use in children. Objective：To investigate the efficacy and safety of dezocine in postoperative analgesia in children, and to provide a suitable reference dose for analgesia in postoperative children. Design：Singlecenter randomized controlled study. Methods：With the preoperative classification of ⅢⅣ by the American Society of Anesthesiologists (ASA), patients directly transferred to PICU after congenital heart disease (CHD) were enrolled from Children's Hospital of Chongqing Medical University at the age of >28 d at the time of surgery. A random number table was used and the grouping results were sealed in an envelope. The PICU physician on duty was responsible for the subject assignment, and the bedside nurse performed the intervention. All patients were randomized into 5 groups. Subjects in the experimental group were continuously injected with lowdose (group D1), mediumdose (group D2), or highdose (group D3) dezocine after the operation, and those in the control group were injected with sufentanil (group SF) or morphine (group M). The postoperative pain and sedation scores were observed. The outcome observers and data analysts were not blinded. Invasive ventilatorassisted ventilation, symptomatic management, and midazolam sedation were performed after admission to the PICU in both five groups. D1, D2, and D3 groups received dezocine 20, 30, 40 μg·kg-1·h-1 respectively, SF group received sufentanil 0.08 μg·kg-1·h-1, and M group received morphine 20 μg·kg-1·h-1. All intravenous injection was administrated through a syringe pump. Face Pain Scale (FPS) and Child Revised Impact of Events Scale (CRIES) were used to evaluate pain, and Ramsay and ComfortB were used to score sedation. All scales were completed by PICU specialist nurses. Main outcome measures：The percentage of satisfaction with analgesia/sedation at 1 h, 4 h, 8 h, 12 h, and 24 h after the operation. Results：A total of 152 children with congenital heart disease were enrolled, 30, 30, 31, 31, and 30 in groups D1, D2, D3, SF, and M, respectively, all of whom completed the designed intervention and observation. There were no significant differences in age, weight, sex, extracorporeal circulation time, pediatric critical illness score (PCIS) and preoperative ASA grading among the 5 groups. Compared with group M, the FPS scores were higher in the D2 group at 24h and the D3 group at 4 h and 24 h; the CRIES scores were higher in the D1 and D2 groups at 1 h and 4 h and in the D3 group at 4 h and 24 h ; the Ramsay scores were higher in the D2 and D3 groups at 1 h and 4 h; the ComfortB scores were higher in the D1 group at 4 h and 12 h, in the D2 group at 1h and 4 h and in the D3 group at 1 h, 4 h, and 12 h. All the differences were statistically significant. There was no statistically significant difference in analgesia/sedation satisfaction between the D group(D1, D2, D3) and the SF group in terms of the four scales. The differences in vital signs and related indexes were not statistically significant among the 5 groups at each postoperative time point. The proportion of additional sedative/analgesic drugs was lower in groups D1 and D2 than in groups M and SF, and the differences were statistically significant. Two cases of hypotension and one case of respiratory depression were observed in group M. Conclusions：The analgesic effect of dezocine in postoperative children with congenital heart disease is better than that of morphine and comparable to that of sufentanil. Dezocine has fewer adverse reactions.

Key words: Dezocine, Children, Analgesia, Sedation