Comparison of the Effects of High, Low and Minimal Flow Anesthesia Managements on ORI and Partial Oxygen Pressure

Inclusion Criteria: * ASA II and III patients, * Aged between 18-75 years, * who were scheduled to undergo elective open abdominal surgery lasting \<60 minutes under general anesthesia Exclusion Criteria: * refusal of consent to study inclusion by the patient or his/her guardian, * inability to use the sensor due to finger deformation or hypoperfusion, * having a history of malignant hyperthermia, * presence of clinically significant anemia, morbid obesity, alcohol or drug addiction, having a severe cardiac, renal or hepatic impairment, * having a history of cerebrovascular disease, * being a pregnant or presently lactating and having local anesthetic or opioid sensitivity