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.