Inclusion Criteria:  patients 19 years of age or older the American Society of Anesthesiologists classification 1-3 patients undergoing laparoscopic cholecystectomy at Severance Hospital  Exclusion Criteria:  Emergency surgery, patients with heart disease or arrhythmias, patients undergoing concurrent surgery other than laparoscopic cholecystectomy, obesity (BMI>30), patients who were admitted on the surgery day, foreigners, illiteracy