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.
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.