Epileptogenic Effect of Sevoflurane

Abstract

Background: Sevoflurane has become the gold standard for inhalation induction in children. However in children as in adults, epileptiform electroencephalographic signs have been described under high concentrations of sevoflurane. The aim of this study was to determine the minimal alveo- lar concentration (MAC) of sevoflurane associated with the occurrence of major epileptiform signs (MES) in 50% children under steady-state conditions. The MAC of MES (MAC MES) was determined in 100% oxygen and with the addition of 50% nitrous oxide or after the injection of alfentanil (ALFENTA). Methods: Seventy-nine children (3–11 yr), undergoing elective surgery and premedicated with hydroxyzine were included. After induction by inhalation and tracheal intuba- tion, a 10-min period with a stable expired fraction of sevo- flurane was obtained. The MES were defined as rhythmic polyspikes or epileptiform discharges. Electroencephalo- graphic recordings were blindly analyzed by two indepen- dent experts. The MAC MES were determined by the Dixon method: the concentration of sevoflurane was determined by the result from the previous patient: increase of 0.2% if MES were absent or decrease of 0.2% if MES were pres- ent. Three consecutive series were performed: (1) in 100% oxygen (MAC MESO2 ); (2) in 50% oxygen and 50% nitrous oxide (MAC MESN2O ); and (3) in 100% oxygen with a bolus of alfentanil (MAC MESALFENTA ). Results: The MAC MESO2 was 4.3 ± 0.1% (mean ± SD), the MAC MESN2O and the MAC MESALFENTA were higher, respectively: 4.6 ± 0.2% (P = 0.01) and 4.6 ± 0.2% (P = 0.02). Conclusions: In children premedicated with hydroxyzine, the MAC MES of sevoflurane calculated in 100% O2 cor- responded to 1.75 surgical MAC. In addition, our results have demonstrated a moderate effect of nitrous oxide and alfentanil in raising the threshold of MES.