Sevoflurane mask induction of anaesthesia is associated with epileptiform EEG in children

Background: Sevoflurane inhalation induction of anaesthesia is widely used in paediatric anaesthesia. We have found that this method is frequently associated with epileptiform electroencephalogram (EEG) in adults, especially if controlled hyperventilation is used. Methods: We assessed EEG during sevoflurane inhalation induction in 31 children, aged 2-12 yr. Anaesthesia was induced with 8% sevoflurane in O-2 in N2O 1:2. The patients were randomized to undergo controlled ventilation (CV group), or to breathe spontaneously (SB group) for 5 min. EEG was recorded as were noninvasive blood pressure and heart rate (HR). EEG recordings were classified by a clinical neurophysiologist. Results: Three different types of interictal epileptiform discharge were detected. Suppression with spikes (SSP) was found in 25% and 0% in the CV and SB groups, rhythmic polyspikes (PSR) in 44% and 20%, and periodic epileptiform discharges (PED) in 44% and 0% (P <0.01), respectively. The incidence of all different types of interictal epileptiform discharge (SSP+PSR+PED) was 88% and 20% (P <0.001), respectively. Epileptiform EEG was associated with increased heart rate and blood pressure during anaesthetic induction. Conclusion: Both ventilation modes produced epileptiform EEG. With controlled ventilation, epileptiform discharges were seen in 88% of children. This warrants further studies of the suitability of this induction type in general, and especially in children with epilepsy.