The relationship between age and minimum alveolar concentration of sevoflurane for maintaining bispectral index below 50 in children.

We evaluated the minimum alveolar concentration of sevoflurane required to maintain the bispectral index below 50 in children. We studied 55 children, divided into 1-year-old, 2- to 4-year-old and 5- to 9-year-old groups and used Dixon's up-and-down method and probit analysis. In the 1-year-old group, the bispectral index values remained above 50, with the end-tidal sevoflurane concentration reaching 4.0% or higher. The minimum alveolar concentration of sevoflurane for maintaining the bispectral index below 50 was significantly higher in the 2- to 4-year-old group (2.33%, 95% CI 2.25-2.57) than in the 5- to 9-year-old group (2.10%, 95% CI 1.94-2.25; p = 0.005). We conclude that assessing the depth of anaesthesia using bispectral index is unreliable in children aged < 2 years anaesthetised with sevoflurane.