The minimum effective dose (MED90) of remimazolam for inhibiting responses to the insertion of a duodenoscope during ERCP

Abstract Backgroundː Compared to midazolam, remimazolam has a faster onset and offset of hypnotic effect, as well as cardiorespiratory stability, this study aims to determine the minimum effective dose (MED 90 ) of remimazolam to inhibit responses to insertion of a duodenoscope during ERCP. Methods ːA dose-response study was carried out undergoing ERCP who received remimazolam-alfentanil anesthesia using 10 µg/kg of alfentanil between September 2021 and November 2021. The initial dose of remimazolam was 0.2 mg/kg. The dose was then decided based on the responses of earlier patients by exploiting the sequential ascend and descend according to a 9: 1 biased coin design. Upon failure, the dose of remimazolam was increased by 0.025 mg/kg in the next patient. When the insertion was successful, the succeeding patient was randomized to an identical dose or a dose that was lower by 0.025 mg/kg.The MED 90 of remimazolam for inhibiting responses to the insertion of a duodenoscope during ERCP was calculated. Adverse events and complications of remimazolam were recorded. Resultsː A total of 55 elderly patients (age>65) were included in the study. 45 successfully anesthetized patients, and 10 unsuccessfully. The MED 90 of remimazolam was 0.300 mg/kg (95% CI = 0.287–0.320). MED 95 was 0.315 (95% CI = 0.312–0.323) and MED 99 was 0.323 (95% CI = 0.323–0.325). Among the patients, 9 patients developed hypotension, 2 patients developed bradycardia and 1 patient developed tachycardia, and hypoxia occurred in 2 patients. Conclusion ː A loading dose of 0.300 mg / kg of remimazolam for elderly patients undergoing ERCP can safely, effectively, and quickly induce patients to fall asleep and inhibit responses to the insertion of a duodenoscope. Trial registration： The study protocol was registered at ClinicalTrials.gov (NCT05053763).