Age-Dependent Burst Suppression During Anesthesia in Young Children with Congenital Heart Disease: The Impact of Anesthetic Depth

<b>Background/Objectives</b>: Electroencephalography (EEG) is increasingly used in pediatric anesthesia to detect abnormal brain activity such as burst suppression (BS), a marker of profound cortical inactivation. The objective of this study was to assess anesthetic depth using bilateral spectral edge frequency (SEF) and to determine the incidence of frontal cortical BS in young children undergoing cardiac surgery with extracorporeal circulation (ECC) under sevoflurane anesthesia. <b>Methods</b>: Twelve children, divided into two age groups (<12 months and 12-36 months), were included. EEG sensors were placed on the forehead and continuously monitored with SedLine^®. BS and SEF were analyzed using linear mixed-effects models, accounting for age group and repeated measurements across the procedure. <b>Results</b>: BS did not differ significantly over time. Across the full surgical procedure, higher SEF was associated with lower BS. However, children <12 months exhibited a stronger SEF-BS relationship, suggesting greater susceptibility to BS compared to older children. Before and during ECC, SEF and age group were not significantly related to BS. Random effects indicated moderate to substantial between-subject variability. Scatterplots showed a negative SEF-BS relationship overall, but weak and inconsistent associations during specific perioperative phases, underscoring the phase-dependent nature of SEF-BS dynamics. <b>Conclusions</b>: SEF is an age-sensitive marker of anesthetic depth during sevoflurane anesthesia with ECC, with children <12 months showing greater susceptibility to BS. These findings highlight the importance of individualized, age-adjusted anesthesia monitoring strategies in pediatric cardiac surgery.