Remimazolam for induction of anesthesia in elderly patients with severe aortic stenosis: a prospective, observational pilot study

BACKGROUND: Remimazolam, a novel benzodiazepine, has been reported to cause less hypotension than propofol during induction of anesthesia. Therefore, remimazolam might be a valuable option in elderly patients with severe aortic stenosis who are considered to be the most vulnerable to hemodynamic instability. We aimed to evaluate the feasibility and hemodynamic effects of remimazolam as an induction agent in elderly patients with severe aortic stenosis. METHODS: This prospective, open-label, single-arm, observational pilot study was conducted in a university hospital between November 2020 and April 2021. We included 20 patients aged 65 years or older scheduled for transcatheter or surgical aortic valve replacement for severe aortic stenosis under general anesthesia. Patients were administered intravenous remimazolam infusion at 6 mg/kg/h combined with 0.25 μg/kg/min of remifentanil infusion. The primary outcome was the vasopressor dosage between the induction of anesthesia and the completion of tracheal intubation. The secondary outcomes included hemodynamic changes, bispectral index changes, and the time from the start of remimazolam infusion to loss of consciousness. We also recorded awareness during anesthesia induction and serious adverse events related to death, life-threatening events, prolonged hospitalizations, and disability due to permanent damage. RESULTS: Twenty patients aged 84 [79–86] (median [interquartile range]) with American Society of Anesthesiologists physical status 4 were analyzed. Ephedrine 0 [0–4] mg and phenylephrine 0.1 [0–0.1] mg were administered to 14/20 patients (3 doses in 1 patient, 2 doses in 4 patients, and one dose in 9 patients). Loss of consciousness was achieved at 80 [69–86] s after the remimazolam infusion was started. The mean arterial pressure decreased gradually after loss of consciousness but recovered immediately after tracheal intubation. The bispectral index values gradually decreased and reached < 60 at 120 s after loss of consciousness. Neither awareness during induction of anesthesia nor serious adverse events, such as severe bradycardia (< 40 bpm), life-threatening arrhythmia, myocardial ischemia, or anaphylactic reactions were observed. CONCLUSIONS: Remimazolam could be used as an induction agent with timely bolus vasopressors in elderly patients with severe aortic stenosis. TRIAL REGISTRATION: UMIN Clinical Trials Registry, identifier UMIN000042318.