The BIS group (n=90) was monitored for sedation depth using BIS during ESD.

The no-BIS group (n=90) was monitored by observer's assessment alertness/sedation scale (OAA/S).

For double blind method, BIS sensors were attached to all patients, but only BIS-group was measured by the value. BIS monitor was pushed back toward the anesthesiologist so that the physician could not see it. 3 L/min of oxygen was delivered by a nasal cannula to all patients throughout the procedure. Blood pressure was recorded every 5 minutes and heart rate, peripheral oxygen saturation were measured continuously. For induction of sedation, propofol 1 mg/Kg and lidocaine 30mg was administered throughout IV line and immediately followed by continuous infusion of propofol 0.04-0.06 mg/Kg/min and remifentanil 0.05 mcg/Kg/min. The evaluation of sedation depth using OAA/S was performed at 1 minute after propofol administration, endoscopy insertion, submucosal inflation by 1:100000 epinephrine with indigocarmine, initial submucosal dissection and when the patient had restlessness or coughing additively.

The evaluation of sedation depth using OAA/S will be performed at 1 minute after propofol administration, endoscopy insertion, submucosal inflation by 1:100000 epinephrine with indigocarmine, initial submucosal dissection and when the patient have restlessness or coughing additively.