Sevoflurane anesthesia commonly causes emergence agitation (EA) in children. One previous study has reported that the use of nitrous oxide (N₂O) during the washout of sevoflurane may reduce EA by decreasing the residual sevoflurane concentration, while many animal studies suggest that N₂O poses a potential risk to children. The present study was designed to compare EA in children assigned to receive sevoflurane with N₂O (group N) or sevoflurane alone (group S).

We enrolled 80 children aged 3-10 years. Anesthesia was induced with 5 mg/kg thiopental sodium, 0.6 mg/kg rocuronium and 0.5 mg/kg ketorolac, and was maintained with 50% N₂O and sevoflurane in group N or with sevoflurane alone in group S. The sevoflurane concentration was adjusted with a bispectral index (BIS) of 40-60. After completion of the surgery, N₂O and sevoflurane were simultaneously discontinued and replaced with oxygen (O₂) at 6 L/min. End-tidal sevoflurane concentration (Et Sevo) (%), BIS at the end of surgery, Et Sevo at recovery of self-respiration and emergence profiles were recorded. EA occurrence, pain score and rescue fentanyl consumption were assessed in the postanesthesia care unit.

Et Sevo was significantly lower in group N (1.9%) than in group S (2.3%) at the end of surgery. However, there were no differences in Et Sevo at recovery of self-respiration, emergence times, the incidence of EA, pain score or dose of rescue fentanyl between the groups.

In children undergoing adenotonsillectomy with preemptive ketorolac, anesthetic maintenance using sevoflurane alone does not affect the incidence of EA or emergence profiles compared to anesthetic maintenance using sevoflurane with N₂O.