Comparison of optic nerve sheath diameter measurements in coronary artery bypass grafting surgery with pulsatile and non-pulsatile flow

Abstract

Background and Objectives: In coronary artery bypass grafting (CABG) surgeries, monitoring intracranial pressure (ICP) is crucial due to neurological risks. Although pulsatile flow (PF) during cardiopulmonary bypass (CPB) is considered more physiological than non-pulsatile flow (NPF), its impact on ICP remains unclear. This study aimed to compare preoperative and postoperative optic nerve sheath diameter (ONSD) measurements between PF and NPF techniques to evaluate their effect on ICP changes. Materials and Methods: Sixty patients undergoing elective CABG (aged 45–75 years, ASA II-III-IV) were enrolled and divided into two groups depending on the cardiopulmonary bypass technique determined by the surgeon: PF (Group P, n = 30) and NPF (Group NP, n = 30). ONSD measurements were performed with ultrasound before surgery (Tpreop) and after surgery (Tpostop). Hemodynamic parameters and jugular and carotid vessel diameters were also recorded. Statistical analysis included t-tests, Mann–Whitney U-tests, chi-square tests, and Pearson correlation. Results: Both groups demonstrated significant increases in ONSD postoperatively compared to preoperative values (p < 0.001). However, no statistically significant difference in the magnitude of ONSD change was observed between the PF and NPF groups (p > 0.05). Group P showed lower ejection fractions and higher total inotrope requirements compared to Group NP (p < 0.01), but these factors did not translate into differences in postoperative ICP dynamics. Conclusions: ONSD measurements increased significantly after CABG surgery, regardless of perfusion type. PF and NPF strategies were comparable in terms of their effects on ICP as reflected by ONSD changes. ONSD ultrasonography appears to be a simple, rapid, and non-invasive tool for perioperative ICP monitoring in cardiac surgery. Further studies are needed to confirm these findings with dynamic intraoperative monitoring and neurocognitive assessments.