• S Kanazawa, Y Oda, C Maeda, and R Okutani.
• Department of Anesthesiology, Osaka City General Hospital, Osaka, Japan.
• Acta Anaesthesiol Scand. 2016 Feb 1; 60 (2): 177-82.

BackgroundWe examined the hypothesis that the minimum alveolar concentration of desflurane for maintaining bispectral index (BIS) below 50 (MACBIS 50 ) decreases with advance of age.MethodsSixty young (20-30 year), middle-aged (31-65 year) and elderly (66-80 year) patients were included (n = 20, each group). Five minutes following the start of continuous intravenous administration of remifentanil at 0.25 μg/kg/min, general anaesthesia was induced with propofol 2 mg/kg and rocuronium 0.8 mg/kg to facilitate tracheal intubation. Infusion of remifentanil was stopped immediately after tracheal intubation. When BIS began to increase > 60, maintenance of anaesthesia was started with an end-tidal desflurane concentration of 4.0% and maintained for 10 min followed by 1-min assessment of BIS taken at 10-s intervals. MACBIS 50 of each age group was estimated by up-down methodology.ResultsMACBIS 50 of desflurane in young, middle-aged and elderly patients was 4.25% end-tidal (95% confidence intervals 4.04-4.46), 3.58% (3.38-3.79) and 2.75% (2.50-3.00) respectively. MACBIS 50 was higher (P = 0.011) in young patients and lower (P = 0.012) in elderly patients than those in middle-aged patients.ConclusionsAdvance in age significantly decreased the concentrations of desflurane required to maintain BIS below 50. BIS reflected age-associated decrease in end-tidal concentrations of desflurane required for maintaining adequate depth of anaesthesia during resting state.© 2015 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

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