A comparison of bispectral index and spectral entropy during sevoflurane anesthesia in children

ABSTRACT

BACKGROUND: Bispectral index (BIS) is a useful tool to assess depth of anesthesia. Recently, spectral entropy has been promoted as a monitor of anesthetic depth in adult, but its characteristics in children remains poorly defined. This study was to compare BIS and entropy indices during sevoflurane anesthesia in children. METHODS: Forty children (aged 1-12 yr) scheduled for ENT surgery, were included. Anesthesia was induced with 5.0% sevoflurane in O2 6 L/min. Tracheal intubation was performed with rocuronium 0.6 mg/kg. Heart rate, blood pressure, end-tidal sevoflurane concentration (Etsev), BIS, response entropy (RE) and state entropy (SE) were measured every 5 minutes. The correlation between BIS and entropy index and Etsev was calculated, RESULTS: The BIS, SE and RE values decreased with induction and increased with recovery. The BIS, RE, and SE values were inversely proportionally related to the Etsev. The RE and SE values were closely correlated with the BIS values (respectively r = 0.948 and r = 0.946, P< 0.001). CONCLUSIONS: We demonstrated a close correlation of SE and RE with Etsev and with BIS during sevoflurane anesthesia in children. State entropy and RE seem to be useful electroencephalographic measures of sevoflurane drug effect in children.