Electroencephalography and Anesthetic Depth in Children Under 2 Years of Age: A Prospective Observational Study.

BACKGROUND

Processed electroencephalogram (EEG) indices are widely used to monitor anesthetic depth. However, their reliability in children under 2 years of age remains questionable. During anesthesia maintenance in this age group, processed EEG indices frequently exhibit unexpectedly elevated values that exceed the intended target range.

AIM

This study aimed to identify EEG spectral parameters associated with false positive elevations in processed EEG indices and investigate their differences from true positive elevations during emergence.

METHODS

This prospective observational study included 50 children aged 4-24 months undergoing general anesthesia. Bispectral index (BIS), patient state index (PSi), and raw EEG were continuously recorded throughout anesthesia. False positive was defined as elevated processed EEG indices when end-tidal sevoflurane concentration was maintained at 0.7-1.3 minimum alveolar concentration, with heart rate and mean blood pressure between 80% and 120% of baseline values. We analyzed EEG power spectra and band power values during periods of false positives and compared them with those of true positives during emergence. Bonferroni-corrected p < 0.05 was considered significant.

RESULTS

False positives in processed EEG indices were observed in 35 (70%) of the children during anesthesia maintenance, occupying 28% of the maintenance phase. These false positives were associated with decreased power in delta (269-174 dB) and theta (115-97 dB) bands, but widespread increases in alpha and beta bands, resulting in elevated spectral edge frequency (19-22 Hz). Notably, EEG band power during false positives significantly differed from those observed during emergence (delta: 52 dB, theta: 38 dB) (all p < 0.001).

CONCLUSIONS

Processed EEG indices may exhibit unexpectedly elevated values during anesthesia maintenance in children under 2 years of age. Quantitative assessments derived from raw EEG data may improve the evaluation of anesthetic depth in this population.