The Effect of Remimazolam on the Baseline TOF Ratio: A Prospective, Clinical Study.

Background: Remimazolam is a newly developed benzodiazepine. Early recovery from anesthesia because of its ultra-short acting effect and less hemodynamic side effects has been reported as the specific advantages of remimazolam. Therefore, the maintenance of anesthesia with propofol may be sometimes switched to remimazolam anesthesia maintenance during surgery because of the risk of delayed awakening and unstable hemodynamics. In the present study, to determine the influence of switching anesthesia from propofol to remimazolam on the baseline TOF ratio, the TOF ratio under remimazolam anesthesia maintenance without any neuromuscular blocking agents was compared to that calibrated after induction of general anesthesia with propofol. Methods: Twelve patients scheduled for elective surgery under general anesthesia in the supine position were investigated. After induction of general anesthesia with remifentanil and propofol, a supraglottic airway was inserted without neuromuscular blockade, and TOF stimulation every 15 s at the adductor pollicis muscle was started with acceleromyography. After stable baseline responses to TOF stimulation being obtained for at least 10 min under propofol anesthesia, the anesthetic agent was switched to remimazolam and TOF stimulation every 15 s was maintained for a further 60 min without any interruption. In each case, the averaged TOF ratio during the last 10 min of TOF monitoring was compared to that during the 10 min immediately before the beginning of remimazolam infusion using a paired t-test. Results: There were no significant differences in the TOF ratios before and after switching anesthesia to remimazolam (1.07 ± 0.03 vs. 1.07 ± 0.03, p=0.325). Conclusion: Switching anesthesia from propofol to remimazolam does not affect the baseline TOF ratio.