Participants in Prewarming group was warmed with forced air warming device (WarmTouch WT 6000 Warming Unit, Medtronic, Minneapolis, MN, USA) over the entire body for 10 minutes before anesthesia was induced in the operating theater. All participants received active warming with forced air warming system from the initiation of anesthetic induction until end of surgery.

In Non-prewarming group, no active warming was conducted before induction of anesthesia. Only standard care was provided with introperative active warming with forced air warming system from the initiation of anesthetic induction until end of surgery.

In the operating theater, participants allocated in Prewarming group received 10 min-prewarming, which is cutaneous warming before induction of anesthesia. For prewarming, forced air warming system (WarmTouch WT 6000 Warming Unit, Medtronic, Minneapolis, MN, USA) was used and the warming temperature of the device was set to 45°C.

Number of Participants whose core temperature was than 36℃ was recorded at each time point.

Number of Participants who suffer shivering at the post anesthetic care unit was recorded. Postoperative shivering was graded by an investigator who did not know the procedure in the operating room; shivering grade was divided into four grades (0 = none, 1 = mild, 2 = moderate, 3 = severe, The Bedside Shivering Assessment Scale)