Determination of the 90% Effective Dose of Remimazolam Continuous Infusion for Preventing Emergence Delirium in Pediatric Patients Undergoing Adenoidectomy or Adenotonsillectomy with Sevoflurane: A Biased Coin Up-and-Down Sequential Trial Design.

Background: Emergence delirium (ED) is a common postoperative complication during the recovery period in pediatric anesthesia. Continuous intravenous infusion of remimazolam can effectively prevent the occurrence of ED. However, the optimal dose for preventing ED in pediatric patients remains unclear. This study aimed to determine the 90% effective dose (ED90) of remimazolam during continuous infusion for preventing ED in children. Methods: This prospective, single-center double-blind trial recruited 52 children aged 3-7 years scheduled to undergo elective adenoidectomy or adenotonsillectomy under sevoflurane anesthesia. Remimazolam was administered via continuous infusion commencing at the induction of anesthesia and terminating 5 minutes prior to the conclusion of surgery. The initial dose of remimazolam was set at 0.8 mg/kg/h, and subsequent doses were adjusted according to the biased coin design up-and-dow sequential allocation method, taking into account the response of the preceding patient. The primary objective was to determine the ED90 of a continuous remimazolam infusion, assessed based on the success or failure of ED prevention using the Pediatric Anesthesia Emergence Delirium (PAED) scale. Results: A total of 52 patients were enrolled in this study. The remimazolam dose ranged from 0.8 to 1.2 mg/kg/h. The estimated ED90 with the 95% confidence interval (95% CI) for preventing ED was 1.08 mg/kg/h (95% CI 1.03 to 1.97 mg/kg/h). The duration of the surgery was 24.72 ± 6.83 minutes. The extubation time, recovery time, and duration of stay in the post-anesthesia care unit (PACU) were 29.94 ± 6.53 minutes, 45.96 ± 10.53 minutes, and 52.58 ± 9.82 minutes, respectively. No severe adverse events were observed within the tested dose range. Conclusion: In pediatric patients undergoing adenoidectomy or adenotonsillectomy under sevoflurane general anesthesia, the ED90 of remimazolam when continuously infused during surgery for the prevention of emergence delirium is 1.08 mg/kg/h (95% CI 1.03 to 1.97 mg/kg/h). Clinical Trial Registration: https://www.chictr.org.cn, identifier ChiCTR2400094727.