Clinical utility of effect-site concentration simulation during remimazolam general anesthesia

This prospective observational study evaluated the clinical utility of effect-site concentration (Ce) simulation during remimazolam anesthesia.

Fifty ASA I-II adult patients undergoing orthopedic surgery were enrolled, with two excluded due to undisclosed benzodiazepine use. Remimazolam was infused at 3 mg/kg/h for induction, and Ce was simulated. Loss and recovery of responsiveness were assessed by verbal stimulation every 30 s, and EEG-derived parameters including BIS and BSR were recorded.

The mean remimazolam Ces at loss and recovery of responsiveness were 0.35 ± 0.08 µg/mL and 0.36 ± 0.07 µg/mL, with no significant difference (p = 0.68). A positive correlation was observed (r = 0.76). The relationship between remimazolam Ce and BIS was weak, and BSR remained 0 in 98% of data points, indicating minimal EEG suppression even at higher concentrations.

Effect-site concentration simulation is useful for estimating adequate anesthetic depth and predicting emergence during remimazolam anesthesia. EEG-derived indices, particularly BIS, have limited reliability. Further studies using TCI systems and higher concentration ranges are needed to refine dosing strategies and fully characterize EEG-drug interactions.