Determination of the effective dose of remimazolam combined with sufentanil for inhibiting body movement during surgical abortion: An up-and-down sequential allocation trial.

Background: Remimazolam, a recently developed anesthetic characterized by its rapid and ultra-short-acting properties, exhibits pharmacological attributes that make it potentially suitable for painless surgical abortion procedures. The objective of this study was to determine the effective dose of remimazolam when administered in combination with sufentanil, with the intention of inhibiting body movement during surgical abortion. Additionally, a secondary objective was to assess the recovery profile from general anesthesia.

Methods: The study enrolled a total of 25 healthy women aged 20 to 40, with a body mass index between 18 and 28 kg/m2, in their first trimester of pregnancy (up to 12 weeks), and American Society of Anesthesiologists status I and II. Anesthesia induction was initiated by administering sufentanil at a dose of 0.1 μg/kg. The modified Dixon up-and-down method was employed to determine the induction dose of remimazolam for each patient.

Results: The 50% and 95% effective dose of remimazolam for inhibitory effects of body movement was estimated using centered isotonic regression to be 0.145 mg/kg (95% CI: 0.115, 0.207), and 0.242 mg/kg (95% CI: 0.232, 0.620), respectively. Five out of 25 (20%) experienced hiccups, with 1 patient having persistent hiccups until the end of the surgery. The mean time to first eye-opening was 51.4 ± 20.5 seconds, and the time to obey verbal command was 54.5 ± 20.6 seconds. Upon arrival at the postanesthesia care unit, 95.7% of the patients achieved a Modified Aldrete score ≥ 9.

Conclusions: The 50% and 95% effective dose of remimazolam for inhibiting body movement during surgical abortion when used in combination with 0.1 μg/kg of sufentanil were 0.145 mg/kg and 0.242 mg/kg, respectively.