In anesthesia, monitoring of core body temperature is one of important factors. Measurement of temperature using a pulmonary artery catheter is representative one of core temperature measurements. The core temperature by a pulmonary artery catheter is compared with the tracheal temperature by an endotracheal tube with thermometer. This study was designed to confirm the accuracy of the endotracheal tube thermometer.

All patients undergoing general anesthesia are monitored core body temperature. Coronary artery bypass graft surgery needs general anesthesia with endotracheal intubation and insertion of pulmonary artery catheter. Using endotracheal tube with thermometer and pulmonary artery catheter, the investigators will measure tracheal temperature and pulmonary artery temperature every 5 minutes for 1 hour after induction of general anesthesia.

Standard monitoring devices (non-invasive BP, electrocardiogram, pulse oxygen saturation) are applied to participants in an operation room, and 1% propofol 1-2 mg/kg and rocuronium 0.8 mg/kg are administered intravenously for induction of general anesthesia. An endotracheal tube with thermometer (Human Endotracheal Tube, Insung Medical Co., Korea) is inserted. After inserting a 9Fr central venous catheter with a pulmonary artery catheter insertion port, core body temperature is measured by a pulmonary artery catheter (Swan-Ganz CCOmbo V, Edwards Lifesciences, Irvine, California, USA).

Tracheal temperature will be compared with pulmonary artery temperature by using Bland-Altman method.

Inclusion Criteria:

• Adult patients over 18-year-old undergoing coronary artery bypass surgery

Exclusion Criteria:

• Emergency surgery

Adult patients over 18-year-old undergoing coronary artery bypass surgery using pulmonary artery catheter