Inclusion Criteria:  Ages between 18 and 65 Patients undergoing elective surgery under general anesthesia Patients with an American Society of Anesthesiologists Classification I or II  Exclusion Criteria:  Patient refusal Emergency surgery Patients with a contraindication for minimal flow anesthesia Uncontrolled diabetes mellitus History of serious systemic disease (cardiac, pulmonary, hepatic) Utilization of another analgesic technique such as central or peripheral nerve blocks