Minimum alveolar concentrations of sevoflurane for maintaining bispectral index below 50 in children.

OBJECTIVE

To determine minimum alveolar concentration (MAC) of sevoflurane for maintaining bispectral index (BIS) below 50 (MAC(BIS50) ) in children.

BACKGROUND

MAC(BIS50) of sevoflurane in adults was reported to be 0.97%, which has not been elucidated in children.

METHODS/MATERIALS: Twenty children, American Society of Anesthesiologists physical status I or II, aged 1-8, were induced and anesthetized with sevoflurane in oxygen. After tracheal intubation, we started maintenance of anesthesia with endtidal sevoflurane concentrations of 2.6%. The endtidal sevoflurane concentration at which BIS was measured was predetermined by the up-down method (with 0.2% as a step size). After 10 min at predetermined endtidal sevoflurane concentrations, BIS was measured for 1 min. MAC(BIS50) was determined using Dixon's up-down method and probit test.

RESULT: MAC(BIS50) of sevoflurane was 2.83% (95% confidence intervals: 2.70-3.14) in children.

CONCLUSIONS

MAC(BIS50) of sevoflurane in children was calculated to be three times as high as in adults. This indicates that high endtidal sevoflurane concentration is required to suppress electroencephalogram activity in children.