Comparison of different weight-based scalars of remimazolam for anesthesia induction in patients with obesity: a randomized controlled trial.

PURPOSE: Patients with obesity pose unique anesthetic challenges. Remimazolam, a short-acting benzodiazepine, is useful for induction and maintenance of general anesthesia, and its pharmacokinetic profile renders it a valuable alternative to traditional anesthetic agents in this population. We aimed to compare its induction doses based on total body weight (TBW) vs lean body weight (LBW) in patients with obesity.

METHODS

We conducted a prospective, single-centre, randomized controlled trial between February 2022 and June 2023 at the Eye and Ear, Nose, and Throat (ENT) Hospital of Fudan University (Shanghai, China). We randomized 40 patients with obesity 1:1 to receive remimazolam (12 mg·kg-1·hr-1) dosed by TBW (N = 20) or LBW (N = 20). Normal-weight controls (N = 20) received TBW-based dosing. We defined loss of consciousness (LOC) as a Modified Observer's Assessment of Alertness/Sedation (MOAA/S) score of 0. The primary outcome was the induction dose (mg·kg-1) for MOAA/S 0 achievement. Secondary outcomes included time to MOAA/S 0, total induction dose, correlation between total induction dose and TBW/LBW, and hemodynamic changes during induction.

RESULTS

Overall, 60 patients were enrolled. The mean (standard deviation [SD]) induction dose of remimazolam was 0.47 (0.11) mg·kg-1 iv in the LBW group of patients with obesity, 0.35 (0.07) mg·kg-1 iv in the TBW group of patients with obesity, and 0.45 (0.08) mg·kg-1 iv in the control (TBW) group, with significant differences among the three groups (P < 0.001). The two one-sided t test confirmed induction dose equivalence between the LBW group of patients with obesity and the control (TBW) group, but not between the TBW group of patients with obesity and the control (TBW) group.

CONCLUSIONS

At 12 mg·kg-1·hr-1 iv, remimazolam dosing based on LBW in patients with obesity resulted in equivalent induction doses compared with normal-weight patients dosed by TBW. Total-body-weight-based dosing in patients with obesity resulted in a shorter duration to LOC.

STUDY REGISTRATION: www.ChiCTR.org.cn ( ChiCTR2200056641 ); first posted 9 February 2022.