Abstract
This study is the first to report 50% and 95% effect-site concentrations (EC50 and EC95, respectively) of the new short-acting benzodiazepine, remimazolam, for the successful insertion of i-gels with co-administration of fentanyl. Thirty patients (38 ± 5 years old, male/female = 4/26) were randomly assigned into five groups to receive one of five different remimazolam doses (0.1, 0.15, 0.2, 0.25, and 0.3 mg/kg bolus followed by infusion of 1, 1.5, 2, 2.5, and 3 mg/kg/h, respectively, for 10 min), which were designed to maintain a constant effect-site concentration of remimazolam at the time of i-gel insertion. At 6 min after the start of remimazolam infusion, all patients received 2 µg/kg fentanyl. i-gel insertion was attempted at 10 min and the success or failure of insertion were assessed by the patient response. Probit analysis was used to estimate the EC50 and EC95 values of remimazolam with 95% confidence intervals (CIs). In the five remimazolam dose groups, two, two, four, five, and six of the six patients in each group had an i-gel successfully inserted. Two patients in the lowest remimazolam dose group were conscious at the time of i-gel insertion and were counted as failures. The EC50 and EC95 values of remimazolam were 0.88 (95% CI, 0.65–1.11) and 1.57 (95% CI, 1.09–2.05) µg/ml, respectively. An effect-site concentration of ≥ 1.57 µg/ml was needed to insert an i-gel using remimazolam anesthesia, even with 2 µg/kg fentanyl.
Trial registration: The study was registered in Japan Registry of Clinical Trials on 19 April 2021, Code jRCTs041210009.
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Acknowledgements
We thank co-research doctors of the Department of Anesthesiology and Intensive Care, Hamamatsu University School of Medicine. We thank Victoria Muir, PhD, from Edanz Group (https://www.jp.edanz.com/ac) for editing a draft of this manuscript.
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Financial support was provided solely from departmental sources.
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YN helped conceive this study. YN and TK helped design this study. Patient recruitment and data collection were performed by HN. HN, MS and KM analyzed the data. HN wrote the first draft of the manuscript. TK edited the manuscript. All the authors read and approved the final manuscript.
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This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Clinical Research Review Board of Hamamatsu University School of Medicine (Date 15 April 2021/No. CRB4180008).
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Nishimoto, H., Kurita, T., Shimizu, M. et al. Predicted effect-site concentrations of remimazolam for i-gel insertion: a prospective randomized controlled study. J Clin Monit Comput (2024). https://doi.org/10.1007/s10877-024-01135-4
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DOI: https://doi.org/10.1007/s10877-024-01135-4