An evaluation of the relationship between BIS and MOAA/S during remimazolam-sufentanil induction: a prospective...

Both the Bispectral Index (BIS) and the Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scale are commonly used to evaluate the depth of anesthesia in studies investigating the effective dosing of remimazolam. However, their correlation remains unclear. This prospective observational study aimed to characterize the correlation between BIS values and MOAA/S scores during induction of anesthesia with remimazolam-sufentanil in elderly and non-elderly patients.

Sixty patients were enrolled and stratified into elderly and non-elderly cohorts (n = 30 each). All participants received intravenous sufentanil (0.1 μg/kg), followed by remimazolam infusion (0.16 mg/kg in elderly patients; 0.22 mg/kg in non-elderly patients). BIS values and corresponding MOAA/S scores were recorded at 1-min intervals for 5 min after induction. The minimum BIS value and its corresponding MOAA/S score were also captured. Spearman's rank correlation and Cohen's kappa coefficient were used to assess the relationship and agreement between BIS < 60 and MOAA/S = 0. A generalized linear mixed model (GLMM) was applied to evaluate the association between BIS and the probability of deep sedation (MOAA/S = 0).

The correlation between BIS and MOAA/S showed a dynamic pattern, demonstrating a moderate association at the initiation of induction (T1; r = 0.681, p < 0.001) that progressively weakened over time. The area under the receiver operating characteristic curve (AUC) of BIS for predicting deep sedation (MOAA/S = 0) was 0.635 in elderly patients and 0.780 in non-elderly patients. The GLMM identified a significant non-linear association between BIS and the probability of deep sedation (χ² (1) = 6.62, p = 0.010). Overall agreement between BIS and MOAA/S was slight (κappa = 0.175).

Bispectral Index and MOAA/S exhibit a complex non-linear relationship and slight concordance during induction with remimazolam-sufentanil.