Half effective dose of rimazolam combined with a subanesthetic dose of esketamine inhibiting response to gastroscopy insertion in elderly patients

Abstract Objective To investigate the half effective dose of rimazolam inhibiting response to gastroscopy insertion when combined with a subanesthetic dose of esketamine in elderly patients. Methods Twenty-six elderly patients, of any gender, aged 65-73 years, with body mass index 19-26 kg/m2 and ASA physical state I or II, who underwent painless gastroscopy in Cangzhou Central Hospital from January to May 2022 were selected. Intravenous esketamine 0.25 mg/kg and test dose rimazolam were administered sequentially, and the initial dose of rimazolam was 0.2 mg/kg. The dose of the next patient was determined according to the modified sequential method. If the patient had choking or somatic movement reaction when the gastroscope was placed, it was judged as positive, and the dose of rimazolam in the next patient was increased by one gradient; otherwise, the dose of rimazolam in the next patient was decreased by one gradient, and the dose of adjacent rimazolam was graded to 0.01 mg/kg according to the equal difference method.Termination of the study at the presence of seven positive-negative reaction crossover points. Probit analysis was used to calculate the median effective dose(ED 50 )and the corresponding 95% confidence interval (CI)． The occurrence of adverse effects such as dizziness, nausea and vomiting, muscle twitching, hypoxemia, hypotension, bradycardia, and postoperative cognitive impairment were recorded. Results The ED50 of rimazolam combined with esketamine 0.25 mg/kg inhibiting response to gastroscopy insertion in patients was 0.177 mg/kg (95% CI: 0.161-0.184mg/kg). The total dose of remimazolam was (11.4±3.6) mg, the gastroscope diagnosis and treatment time was (7.5±2.5), the recovery time was (10.2±3.8) min and the stay time in the resuscitation room was (8.4±3.2) min. Postoperative dizziness occurred in 1 case, postoperative weakness in 1 case, and postoperative nausea and vomiting in 1 case; no other adverse reactions were found. Conclusion The ED 50 of rimazolam combined with esketamine 0.25 mg/kg inhibiting response to gastroscopy insertion in elderly patients was 0.177 mg/kg, with no significant circulatory and respiratory adverse effects.