The Effects of Low-Dose Remimazolam Adjunct on Propofol–Remifentanil Anaesthesia in Day Case Gynaecological Surgery: A Retrospective Cohort Study

Background and Objectives: Recent studies suggest that remimazolam, a novel ultra-short-acting benzodiazepine, has an excellent pharmacokinetic and safety profile, favourable for ambulatory procedures. Although remimazolam has been studied as a sole agent for anaesthesia in day case gynaecological surgery, studies assessing its use in combination with other anaesthetics remain scarce. The aim of this study was to investigate the effects of a low-dose remimazolam adjunct on the characteristics of an intravenous propofol–remifentanil anaesthesia regimen. Materials and Methods: A single-centre retrospective observational cohort study was conducted on patients who underwent brief day case gynaecological surgery under general intravenous anaesthesia using remifentanil and propofol from November 2024 to January 2025. The patients were divided into two groups depending on whether they received remimazolam as an adjunct. To account for confounding, propensity scores (PSs) were estimated from baseline characteristics and used to derive stabilised inverse probability of treatment weights (IPTWs). Weighted regression models were then applied to estimate treatment effects on postoperative recovery time measures, consumption of anaesthetics, and incidence of any adverse effects intraoperatively and postoperatively. Cost effectiveness was evaluated using the incremental cost-effectiveness ratio (ICER). Results: The clinical data of 51 patients were retrospectively examined: 32 patients were assigned to the intervention group, and 19 patients were assigned to the reference group; after IPTW and PS trimming, the sum of weights was 22 in the intervention group and 58.8 in the reference group. The use of remimazolam as an adjunct was associated with 3.5 min shorter time to eye opening (p < 0.001) and 3.6 min shorter time to full consciousness (p = 0.002); the total consumption of propofol was decreased by 3 mg/kg (p < 0.001); the median dose of remimazolam adjunct was 0.12 mg/kg, or 10 mg per case. There were no statistically significant adverse effects. ICER was 2.35 € per minute of operating room (OR) time saved. Conclusions: In the setting of day case gynaecological surgery, the addition of remimazolam to a propofol–remifentanil regimen reduced propofol requirements and shortened recovery time without an increase in adverse effects. This may represent a more efficient anaesthetic approach for ambulatory procedures with a comparable safety profile.