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Age-dependency of sevoflurane-induced electroencephalogram dynamics in children.
Akeju, O. 1,3,*; Pavone, K. J. 1,+; Thum, J. A. 3,5,+; Firth, P. G. 1,2; Westover, M. B. 2,3; Puglia, M. 1,3; Shank, E. S. 1,3; Brown, E. N. 1,3,4,5,6; Purdon, P. L. 1,3,4,*
[Article] BJA: British Journal of Anaesthesia. 115(suppl_1) Supplement 1:i66-i76, July 2015.

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Background: General anaesthesia induces highly structured oscillations in the electroencephalogram (EEG) in adults, but the anaesthesia-induced EEG in paediatric patients is less understood. Neural circuits undergo structural and functional transformations during development that might be reflected in anaesthesia-induced EEG oscillations. We therefore investigated age-related changes in the EEG during sevoflurane general anaesthesia in paediatric patients.

Methods: We analysed the EEG recorded during routine care of patients between 0 and 28 yr of age (n=54), using power spectral and coherence methods. The power spectrum quantifies the energy in the EEG at each frequency, while the coherence measures the frequency-dependent correlation or synchronization between EEG signals at different scalp locations. We characterized the EEG as a function of age and within 5 age groups: <1 yr old (n=4), 1-6 yr old (n=12), >6-14 yr old (n=14), >14-21 yr old (n=11), >21-28 yr old (n=13).

Results: EEG power significantly increased from infancy through ~6 yr, subsequently declining to a plateau at approximately 21 yr. Alpha (8-13 Hz) coherence, a prominent EEG feature associated with sevoflurane-induced unconsciousness in adults, is absent in patients <1 yr.

Conclusions: Sevoflurane-induced EEG dynamics in children vary significantly as a function of age. These age-related dynamics likely reflect ongoing development within brain circuits that are modulated by sevoflurane. These readily observed paediatric-specific EEG signatures could be used to improve brain state monitoring in children receiving general anaesthesia.