Change in cerebral circulation during the induction of anesthesia with remimazolam

Purpose Remimazolam is a new ultra-short-acting benzodiazepine with unknown effects on cerebral circulation. We measured total cerebral hemoglobin concentrations, which reflect cerebral blood volume (CBV), and cerebral oxygen saturation, using time-domain near-infrared spectroscopy, which can measure the absolute values of cerebral hemoglobin concentrations. We also measured cerebral blood flow velocity (CBFV) in the middle cerebral artery using transcranial Doppler as an indicator of cerebral blood flow (CBF). We did so to examine the effect of remimazolam on cerebral circulation in humans, as assessed CBV, CBF, and cerebral oxygen saturation. Methods This was a prospective, observational study. Fifteen patients without serious complications scheduled for general anesthesia were recruited. We measured total cerebral hemoglobin concentrations, CBFV, and cerebral oxygen saturation throughout the anesthetic induction course with remimazolam. Results Total cerebral hemoglobin concentrations did not change during the process ( p = 0.51). In contrast, the mean CBFV was reduced by 11% (significant, p = 0.04). The drop in mean blood pressure following the induction of anesthesia was 17%; however, it was within the range of cerebrovascular autoregulation. Moreover, cerebral oxygen saturation increased by 4% (statistically significant, p < 0.01). Conclusions We found that anesthetic induction with remimazolam did not alter CBV and reduced CBF in uncomplicated patients.