Evaluation of Optic Nerve Sheath Diameter Changes During Cardiopulmonary Bypass in Open Heart Surgery

During cardiopulmonary bypass (CPB) in open-heart surgery, direct measurement of intracranial pressure is not feasible. Evaluation of the optic nerve sheath diameter (ONSD) by ultrasonography is considered a reliable method for predicting increases in intracranial pressure. This study aims to investigate changes in ONSD in patients undergoing open-heart surgery with CPB.

Several mechanisms during CPB-including inflammatory response, hemodilution, reperfusion injury, hypothermia-rewarming imbalances, and microembolism formation-can lead to increased intracranial pressure and cerebral edema. Ultrasonographic measurement of ONSD provides a noninvasive means of monitoring these changes. In this study, ONSD will be measured at different time points, while hemodynamic parameters, NIRS values, and arterial blood gas analyses will be recorded simultaneously. The primary objective is to evaluate changes in ONSD, and the secondary objective is to determine the potential impact of these changes on intracranial pressure.