The Median Effective Dose and Bispectral Index of Remimazolam Tosilate for Anesthesia Induction in Elderly Patients: An Up-and-Down Sequential Allocation Trial

Purpose: Remimazolam is a new type of ultrashort benzodiazepine drug with an unclear optimal dose for general anesthesia induction in elderly patients aged >60 years. Therefore, this study aimed to determine the effective dose of remimazolam tosilate induction and explore its correlation with the bispectral index (BIS). Patients and Methods: A total of 42 elderly patients were divided into two age groups: 60-69 (group A) and 70-85 (group B) years. An initial dose of 0.1mg/kg(Group A) and 0.05 mg/kg(Group B) remimazolam tosilate was administered, and the Modified Observer's Assessment of Alertness/Sedation scale was used to assess adequate responses. The dose was calculated using the up-and-down allocation technique based on the previous response. The sequential formula and probit regression model were used to calculate ED50 and BIS50. ED95 was determined using the probit regression model. Results: The ED50 of remimazolam tosilate for anesthesia induction were 0.088 mg/kg (95% confidence interval [CI] 0.071-0.108) and 0.061 mg/kg (95% CI 0.053-0.069) in groups A and B, respectively. ED95 was 0.118 mg/kg (95% CI 0.103-0.649) and 0.090 mg/kg (95% CI 0.075-0.199) in groups A and B, respectively. The remimazolam tosilate administration could decrease BIS. BIS50 was 86.0 (95% CI 83.7-88.6) and 85.4 (95% CI 84.1-86.8) in groups A and B, respectively. Conclusion: During the induction process, patients' consciousness should be observed. The dose of remimazolam tosilate could be chosen after careful consideration of individual variations.