Inclusion Criteria:  ASA physical status 1 to 3 patients, over 18 years of age who will undergo elective open abdominal surgery under general anesthesia  Exclusion Criteria:  being over 75 years old, pregnant, who are contraindicated to use anesthetic drugs, BMI <18 and BMI> 40, who used inotropes or vasopressor drugs before or during the operation, with preoperative lung disease, with left ventricular ejection fraction less than 30%, with suspected right ventricular dysfunction (due to chronic obstructive pulmonary disease (COPD) or obstructive sleep apnea syndrome (OSAS)), with moderate to severe valvular disease, with hemodynamic instability in the perioperative period, with severe peripheral vascular occlusion, with liver failure, with renal insufficiency, with intracranial hypertension and with pulmonary hypertension.