Inclusion Criteria:  Age > 60 years old Physical status ASA 1-3 Undergo elective surgery under general anesthesia with or without regional anesthesia  Exclusion Criteria:  Thermoregulation disturbance Abnormal thyroid function Fever caused by infectious disease in 7 days prior to surgery Pre-induction hypothermia with temperature below 36 degree On routine antipiretic Unstable hemodynamic preoperative and intraoperative