Sedation
All patients received sedation throughout the procedure. At the beginning of the procedure, an intravenous propofol bolus of 0.5 mg/kg was administered, and a nasopharyngeal temperature probe was inserted and located in the esophagus to measure the esophageal temperature during the procedure. Maintenance of sedation was performed with a continuous intravenous propofol administration with a dosage of 1.25~2 mg/kg/hr. As an analgesic, an intravenous drip infusion of buprenorphine with a dosage of 1.0 µg/kg was also administered at the beginning of the procedure and was properly added if patients complained of pain. The bispectral index was continuously monitored by a BIS monitoring system (A-3000 BIS XP Platform, Aspect Medical Systems, Newton, MA) to evaluate the sedation level of the patients. To maintain the BIS index level between 50 and 70, an intravenous propofol bolus of 0.5 mg/kg was additionally administered, and the dosage of the continuous intervenous propofol administration was also adjusted according to the sedation level of the patients, if necessary12-13.