Effects of Extracorporeal Circulation Techniques on Cerebral Perfusion in CABG Surgery

This prospective study aims to compare the effects of minimal invasive extracorporeal circulation (MiECC) and conventional reservoir-based extracorporeal circulation techniques on cerebral perfusion in patients undergoing elective coronary artery bypass graft (CABG) surgery. Although the adverse effects of cardiopulmonary bypass on cerebral perfusion and oxygenation are well recognized, the relationship between these effects and changes in intracranial pressure has not been fully elucidated. In this context, ultrasonographic measurement of optic nerve sheath diameter (ONSD), a non-invasive surrogate marker of intracranial pressure, will be used in combination with near-infrared spectroscopy (NIRS) to enable a comprehensive assessment of cerebral perfusion and oxygenation. Between February 2026 and February 2027, a total of 70 ASA II-III patients scheduled for elective CABG surgery will be prospectively enrolled and allocated according to the extracorporeal circulation technique used. Perioperative ONSD measurements will be performed by a single anesthesiologist blinded to the perfusion technique. The primary endpoint is the comparison of perioperative changes in ONSD between the two techniques. Secondary endpoints include the correlation between ONSD and NIRS values, incidence of cerebrovascular events, extubation time, duration of intensive care unit and hospital stay, perioperative hemodynamic parameters, and postoperative complications. This study is expected to provide clinically relevant data on the cerebral effects of different extracorporeal circulation strategies and contribute to perioperative neuromonitoring practices in cardiac surgery.

Inclusion Criteria: * Age ≥ 18 years * Scheduled for elective coronary artery bypass graft (CABG) surgery * American Society of Anesthesiologists (ASA) physical status II-III * Planned use of extracorporeal circulation during surgery * Ability to provide written informed consent Exclusion Criteria: * Age \< 18 years * ASA physical status other than II-III * Emergency surgery * Pregnancy * History of neurological disease affecting consciousness or decision-making capacity * History of psychiatric disease affecting decision-making capacity * History of head trauma within the previous 24 hours * Presence of carotid artery stenosis or significant carotid artery disease * Coagulation disorders (INR \> 1.25, aPTT \> 35 s, or platelet count \< 100,000/μL) * Reoperation (redo cardiac surgery) * Congestive heart failure * Chronic kidney failure * Sepsis * Hypoxia * Ocular trauma * Optic nerve pathology