Electroencephalograms in children during isoflurane anesthesia

The electroencephalograms (EEG) of 55 children under isoflurane anesthesia were studied to elucidate any change in pattern with age. The children ranged from 1 month to 14 years of age were divided into six age groups. The standard minimum alveolar concentration (MAC) was determined in each group. Anesthesia was induced using the slow induction method, and EEG was recorded at isoflurane concentrations of 1.5 MAC in 100% oxygen, 1.0 MAC in 100% oxygen, and 1.0 MAC under administration of 66% nitrous oxide in oxygen. Ventilation was controlled mechanically (end-tidal CO₂ 35–40 mmHg). At 1.5 MAC, the incidences of burst suppression in the groups of 6 months to 6 years of age were significantly less than in groups older or younger than that age (P<0.05). Except for infants less than 6 months of age, the mean values of maximum amplitude at 1.0 MAC were two to three times of those in adults. Children 3–6 years of age showed the highest value of 427.0±83.5 μV. This paper was presented in part at the annual meeting of the Japan Society of Anesthesiology, Osaka, March, 1991.