Determining the Median Effective Dose of Remimazolam for Anesthesia Induction in Patients Undergoing Endoscopic Retrograde Cholangiopancreatography: An Age-Stratified Study

Yan Meng, Youping Song, Chen Gao, Sheng Wang, Keqiang He, Min Xu Department of Anesthesiology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, People’s Republic of ChinaCorrespondence: Min Xu, Email [email protected] Keqiang He, Email [email protected]: Endoscopic Retrograde Cholangiopancreatography (ERCP) requires precise anesthesia control. Remimazolam is ideal for induction due to its rapid onset and minimal cardiorespiratory impact, but its optimal dose across ages is unclear. This study determined the median effective dose (ED50) of remimazolam for ERCP induction and assessed the influence of age.Methods: In this prospective study, 110 patients aged 50– 89 years (ASA I–III, BMI 18– 30 kg/m2) scheduled for ERCP were stratified into four age groups: R1 (50– 59), R2 (60– 69), R3 (70– 79), and R4 (80– 89). The Dixon up-and-down method was used, with the initial dose for R1 set at 0.1 mg/kg remimazolam and sequentially reduced by 0.01 mg/kg for the first patient in each older group. Patients received 0.1 μg/kg sufentanil prior to the intravenous administration of a predetermined dose of remimazolam. Anesthesia success was defined as a Modified Observer’s Assessment of Alertness/Sedation (MOAA/S) score of 0 at 3 minutes after intravenous remimazolam administration, which served as the endpoint for determining the effective induction dose.Results: To determine the effective dose for inducing anesthesia, the ED50 of remimazolam were calculated for groups R1 to R4 as follows: 0.122, 0.108, 0.093, and 0.078 mg/kg, respectively. Similarly, the dosage required to achieve ED95 for the same groups was determined to be 0.132, 0.122, 0.113, and 0.090 mg/kg.Bivariate and multivariable linear regression analyses confirmed a significant inverse correlation between age and remimazolam dose requirement (r = − 0.829, p < 0.001), with age remaining an independent predictor after adjusting for confounders.Conclusion: This study confirms a significant and independent inverse correlation between age and the required induction dose of remimazolam for ERCP. The ED50 decreases progressively with advancing age. We recommend a tailored reduction in the remimazolam induction dose for geriatric patients to enhance safety.Keywords: remimazolam, endoscopic retrograde cholangiopancreatography, median effective dose, age-stratified