Remimazolam infusion associated with easier mask ventilation than propofol during anaesthesia induction

BACKGROUND: Benzodiazepines facilitate mask ventilation due to their airway relaxant properties. Remimazolam, an ultra-short-acting benzodiazepine, may offer advantages during anaesthesia induction. This study evaluated the difficulty of mask ventilation between remimazolam and propofol during the induction of general anaesthesia. METHODS: Seventy-six adult patients scheduled for elective surgery under general anaesthesia were randomised into propofol and remimazolam groups. In the propofol group, general anaesthesia was induced with target-controlled infusion of propofol at an effect-site concentration of 4 µg/mL. In the remimazolam group, continuous infusion of remimazolam was performed at 12 mg/kg/h. The primary outcome was mask ventilation difficulty assessed by the Warters scale. Secondary outcomes included time to achieve loss of consciousness (LOC) and mean blood pressure during induction. RESULTS: The remimazolam group exhibited significantly lower Warters score compared to the propofol group (0.0 [0.0-0.8] vs. 1.0 [0.0-3.0], P = 0.002). The occurrence of mask ventilation difficulties requiring more than one airway device during anaesthetic induction was also significantly lower in the remimazolam group than in the propofol group (odds ratio [95% confidence interval], 0.23 [0.08-0.68]; P = 0.006). Mean blood pressure immediately after LOC was higher in the remimazolam group (P = 0.037), although the incidence of hypotension after induction was comparable between groups. The time required to achieve LOC was longer in the remimazolam group (P < 0.001). CONCLUSION: Compared to propofol, remimazolam induction was associated with easier mask ventilation and more stable blood pressure after LOC, despite a longer time to achieve LOC. REGISTRATION: University Hospital Medical Information Network Clinical Trials Registry (registration number: UMIN000053553; registration date: 7 February 2024; registration URL: https://center6.umin.ac.jp/cgi-bin/ctr_e/ctr_view_reg.cgi?recptno=R000061086).