Comparison of emergence agitation between sevoflurane/nitrous oxide administration and sevoflurane administration alone in children undergoing adenotonsillectomy with preemptive ketorolac

Background: 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). Methods: 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, N N_{2 N}O 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. Results: 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. Conclusions: 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.