Abstract: Objective To investigate the effective dose of remimazolam to inhibit the cardiovascular response to double-lumen endotracheal intubation during general anesthesia with sufentanil in the elderly patients who receiving thoracic non-cardiac surgery. Methods In this study, 21 elderly patients who underwent double-lumen tracheal intubation during thoracic non-cardiac surgery under general anesthesia were selected from October 2022 to April 2023, and the sequential method was used in this study. The first patient received intravenous injection of remimazolam 0.3 mg/kg, and the dose of remimazolam for the next patient was determined according to the cardiovascular response to tracheal intubation of the previous patient. If the cardiovascular response was positive, the dose was increased by 0.01 mg/kg; Instead, the dose of the next patient was decreased by 0.01 mg/kg, and the experiment was terminated when there were ≥6 consecutive alternating positive and negative waveforms. The Probit method was used to calculate the median effective dose (ED50) and the 90% effective dose (ED90) of remimazolam in inhibiting the cardiovascular response to double-lumen tracheal intubation. Results A total of 10 positive and 11 negative cases were observed in 21 patients. The ED50 of remimazolam combined with sufentanil in suppressing the cardiovascular response to double-lumen tracheal intubation during thoracic non-cardiac surgery in the elderly patients was 0.306 mg/kg, with a 95%CI of 0.291-0.328 mg/kg, and the ED90 was 0.322 mg/kg, with a 95%CI of 0.312-0.488 mg/kg. Conclusions The ED50 of remimazolam in inhibiting cardiovascular response to double-lumen endotracheal intubation was 0.306 mg/kg and the ED90 was 0.322 mg/kg in the elderly patients who underwent thoracic surgery under general anesthesia with sufentanil.

Key words: aged, remimazolam, double-lumen tracheal intubation, cardiovascular response, dose-effect relationship