The aim of this study is to examine the effects of patients' clinical and demographic datas on cerebral oxygen saturation values. Brain oxygenation is measured using near infrared spectroscopy (NIRS). The primary outcome measure of the study is the regional oxygen saturation (rSO2) values measured on the monitor at twelve time points. The other primary outcome measures consist of baseline arterial and venous blood gas analysis and baseline activated clotting time measurements.

This prospective observational study analyzes 80 patients between the ages of 25-80 years who are undergoing elective coronary artery bypass grafting (CABG) surgery. Demographic data of the patients such as age, gender, comorbidities, body mass index are recorded. In addition to standard monitoring, cerebral oximetry monitoring (NIRS) is applied to the patients. Baseline arterial and venous blood gas analysis values, baseline activated clotting time measurements are recorded. Durations of anesthesia, surgery , cardiopulmonary bypass , aortic cross- clamping are recorded. Time points for rSO2 values are baseline, induction, sternotomy, cannulation, pump entry, cross clamp placement, 34º C ,36º C, lowest temperature, cross clamp removal, pump exit, skin closure.

Inclusion criteria:

• Accepting to participate in the study
• Undergoing elective coronary artery bypass grafting surgery
• Age 25-80 years Ejection fraction 30% and above

Exclusion criteria:

• Non volunteers
• Age <25 or >80 years
• Ejection fraction below 30%
• Patients with history of neurological disease or neurosurgery
• Emergency surgery
• Concurrent valve surgery
• Patients with history of carotid artery stenosis
• Patients with need for preoperative intraaortic balloon pump or inotropic support

Patients undergoing elective coronary artery bypass grafting surgery