Age-dependent decrease in XXXX concentration for maintaining bispectral index below 50.

@entity1 @entity10233 @entity1875 @entity2898 @entity1937
BACKGROUND: We examined the hypothesis that the minimum alveolar concentration of @entity10233 for maintaining bispectral index (BIS) below 50 (MACBIS 50 ) decreases with advance of age. METHODS: Sixty young (20-30 year), middle-aged (31-65 year) and elderly (66-80 year) @entity1 were included (n = 20, each group). Five minutes following the start of continuous intravenous administration of @entity1937 at 0.25  g/kg/min, general anaesthesia was induced with @entity1875 2 mg/kg and @entity2898 0.8 mg/kg to facilitate tracheal intubation. Infusion of @entity1937 was stopped immediately after tracheal intubation. When BIS began to increase > 60, maintenance of anaesthesia was started with an end-tidal @entity10233 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. RESULTS: MACBIS 50 of @entity10233 in young, middle-aged and elderly @entity1 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 @entity1 and lower (P = 0.012) in elderly @entity1 than those in middle-aged @entity1 . CONCLUSIONS: Advance in age significantly decreased the concentrations of @entity10233 required to maintain BIS below 50. BIS reflected age-associated decrease in end-tidal concentrations of @entity10233 required for maintaining adequate depth of anaesthesia during resting state.
