Optimal Sevoflurane Concentration for Intubation in Combination of Clincal Remifentanil Doses

After setting the end-tidal sevoflurane concentration in a predetermined concentration, remifentanil will be injected according to their group and intubation will be performed 90 seconds after.

After setting the end-tidal sevoflurane concentration in a predetermined concentration, remifentanil will be administered according to their group in 1 minute to prevent remifentanil induced rigidity or complications.

The end-tidal sevoflurane concentration will be set as predetermined, which starts from 2.5 vol% and adjusted by the up-and-down study model which have been described by Dixon JW et al.