Effective concentration of remifentanil for successful i-gel insertion during remimazolam induction

• Published in: Korean journal of anesthesiology Vol. 76; no. 3; pp. 235 - 241
• Main Authors: Choi, Jung Ju, Jung, Wol Seon, Chang, Young Jin, Yoo, Seungbeom, Kwak, Hyun Jeong
• Format: Journal Article
• Language: English
• Published: Korea (South) Korean Society of Anesthesiologists 01.06.2023; 대한마취통증의학회
• Subjects: Adult; Aged; airway management; Anesthesia, General - methods; Anesthetics, Intravenous; Clinical; general anesthesia; Humans; intravenous anesthetics; neuromuscular blocking agents; Piperidines; Propofol; Remifentanil; remimazolam; 마취과학; Neuromuscular blocking agents; General anesthesia; Airway management; Remimazolam; Intravenous anesthetics; Remifentanil
• ISSN: 2005-6419; 2005-7563; 2005-7563
• DOI: 10.4097/kja.22606

Background: Remifentanil can be used as adjuvants during remimazolam induction without neuromuscular blockade. We evaluated the 95% effective concentration (EC) of remifentanil effect-site concentration (Ce) for the successful insertion of an i-gel using the biased-coin up-and-down method in adult patients during remimazolam induction. Methods: Forty 19–65 year-old patients scheduled to undergo surgery using i-gel were enrolled. Anesthesia was induced using remimazolam infusion (12 mg/kg/h). Simultaneously, remifentanil was infused at a predetermined Ce. After 5 min of anesthesia induction, the i-gel was inserted. The 95% EC (EC95) of remifentanil in each patient was determined using a biased-coin up-and-down method based on a successful insertion in a preceding patient. The step size of remifentanil Ce was 0.4 ng/ml. If the insertion failed, remifentanil Ce was increased in the next patient. Following successful insertions, the corresponding concentration decreased in subsequent patients with a probability of 1/19 or was maintained with a probability of 18/19. The time from remimazolam infusion initiation to a bispectral index (BIS) < 60 (time to BIS60) and hemodynamic variables were measured and recorded.Results: The EC95 (95% CI) of Ce was 2.07 (1.94, 2.87) ng/ml. The overall time to BIS60 was 154.0 ± 39.9 s. No patient experienced significant hypotension or bradycardia during remimazolam induction.Conclusions: The EC95 of remifentanil Ce was 2.07 (1.94, 2.87) ng/ml for successful i-gel insertion during remimazolam induction at 12 mg/kg/h without hemodynamic instability in adult patients. Future studies should measure remifentanil Ce in elderly patients or using remimazolam at various infusion doses.