This research attempts to find the optimum dose of remifentanil that can prevent the unnecessary responses such as coughing, gagging, and movement when LMA is inserted during sevoflurane induction in pediatric patients.

Anaesthesia is induced by inhalation with 3% sevoflurane. A predetermined bolus dose of remifentanil is injected over 30 seconds. The LMA is attempted 60 seconds after bolus administration. The starting dose of remifentanil is 0.5μg/kg and a step size is 0.05μg/kg. If LMA insertion is successful or failed in previous patient, an decrement or increment of 0.05μg/kg remifentanil is injected to next patient, respectively.

Inclusion Criteria:

• American Society of Anesthesiologists physical status 1 or 2
• undergoing short elective surgery(i.e Strabismus surgery, Entropion surgery, Inguinal hernia surgery, etc) under general anesthesia

Exclusion Criteria:

• suspected difficult airways
• respiratory disease (chronic obstructive pulmonary disease, upper respiratory infection)
• body mass index > 30 kg/m2
• allergies to the study drugs
• a history of gastric reflux