The Efficacy and Safety of Remimazolam Tosilate versus Etomidate-Propofol in Elderly Outpatients Undergoing Colonoscopy: A Prospective, Randomized, Single-Blind, Non-Inferiority Trial

Objective: The optimal sedation regime during endoscopy remains controversial, especially for elderly outpatients. In this study, we compared the efficacy and safety between remimazolam tosilate (RT) and etomidate-propofol (EP) in elderly outpatients undergoing colonoscopy. Methods: A total of 260 elderly outpatients undergoing sedative colonoscopy were randomized into two groups. Patients in the RT group received a 0.075-mg/kg maintenance dose of remimazolam following an initial dose of 0.15 mg/kg, whereas patients in the EP group (10 mL:20 mg etomidate plus 10 mL:100 mg propofol) received a 0.05-mL/kg maintenance dose following an initial dose of 0.1 mL/kg to maintain a Modified Observer's Assessment of Alertness/Sedation score of ≤ 3 during the procedure. The primary endpoint was the success of the procedure. Secondary endpoints included time metrics, hemodynamics, consumption of fentanyl, etomidate, propofol, and remimazolam, intraoperative body movement, patient and endoscopist satisfaction scores, supplemental dose of sedative and fentanyl, and incidence and severity of adverse events. Results: The procedure success rate was 96.52% in the RT group and 100% in the EP group. The difference in procedure success rate between the RT and EP groups was − 3.48% (95% confidence interval: − 6.81%, − 0.15%). Four patients in the RT group required rescue midazolam. Compared with patients in the RT group, the onset time of the EP group was significantly lower ( p < 0.05), whereas time to fully alert ( p = 0.001), ready for discharge ( p = 0.001), and hospital discharge ( p = 0.002) were all significantly higher in the EP group. However, there were no significant differences in procedure time ( p = 0.846) or cecal intubation time ( p = 0.320) between the two groups. Although the frequency of intraoperative body movement was higher in the RT group, the difference was not significant ( p = 0.508). There were no significant differences in patients' demographic and baseline characteristics, supplemental doses of sedative and fentanyl, or patient and endoscopist satisfaction scores ( p > 0.05). Muscular tremor and pain on injection were recorded more frequently in the EP group ( p < 0.05). However, there were no significant differences in hypoxia, respiratory depression, or incidence of postoperative nausea and vomiting. The severity of adverse events was all mild (grade 1) across both groups. Conclusion: RT may have non-inferior efficacy and a higher safety profile than EP in elderly outpatients undergoing colonoscopy, which suggests that RT may be more suitable for elderly outpatients undergoing colonoscopy. Keywords: remimazolam tosilate, etomidate, propofol, elderly outpatients, colonoscopy