High-density electroencephalographic (EEG) monitoring remains underutilized in clinical anesthesia, despite its obvious utility in unraveling the profound physiological impact of these agents on central nervous system functioning. In school-aged children, the routine practice of rapid induction with high concentrations of inspiratory sevoflurane is commonplace, given its favorable efficacy and tolerance profile. However, few studies investigate topographic EEG during the critical timepoint coinciding with loss of responsiveness – a key moment for anesthesiologists in their everyday practice. We hypothesised that high initial sevoflurane inhalation would better precipitate changes in brain regions due to inhomogeneities in maturation between three different age groups compared with gradual stepwise paradigms utilised by other investigators. Knowledge of these changes may inform strategies for agent titration in everyday clinical settings.
37 healthy children aged five to ten years underwent induction with >=4% sevoflurane in high flow oxygen. Perturbations in anesthetic state was investigated in 23 of these children using 64-channel EEG with Hjorth Laplacian referencing scheme. Topographical maps illustrated absolute, relative and total band power across three age groups: 5-6 years (N = 7), 7-8 years (N = 8) and 9-10 years (N = 8).
Spectral analysis revealed a large shift in total power driven by increased delta oscillations. Well-described topographic patterns of anesthesia, e.g.: frontal predominance, paradoxical beta excitation and increased slow activity, were evident in the topographic maps. However, there were no statistically significant age-related changes in spectral power observed in a midline electrode subset between the groups when responsiveness was lost compared to the resting state.
High initial concentration sevoflurane induction causes large scale topographic effects on the pediatric EEG. Within the minute following unresponsiveness, this dosage may perturb EEG activity in children to an extent where age-related differences are not discernible.