Mortality rates for newborns with congenital heart disease (CHD) have dramatically decreased thanks to surgical methods and medical treatment improvements. Up to 70% of patients may have post- Extracorporeal life support (ECLS) cerebral dysfunction, which can result in long-term cognitive and motor impairment, first showing as brain edema and higher intracranial pressure (ICP). Optic Nerve Sheath Diameter (ONSD) is a non-invasive method of measuring Intracranial Pressure (ICP). The Primary Aim of this study is to identify the correlation between ONSD and ECLS time in newborns who get ECLS.

INTRODUCTION Mortality rates for newborns with congenital heart disease (CHD) have dramatically decreased thanks to surgical methods and medical treatment improvements. As a result, more emphasis is being put on reducing neonatal cardiac surgery morbidity.

Extracorporeal life support (ECLS) is increasingly being given to children, particularly for cardiac causes, according to the Pediatric Extracorporeal Life Support Organization Registry's global report. However, up to 70% of patients may have post-ECLS cerebral dysfunction, which can result in long-term cognitive and motor impairment, first showing as brain edema and higher intracranial pressure (ICP). In addition, pediatric patients may have trouble being diagnosed with acute elevations in IİCP since the signs and symptoms are sometimes unclear.

The gold standard for measuring intracranial pressure (ICP) still involves invasive intracranial devices. In addition, ICP monitors have the potential to cause complications, including bleeding in 1.1-5.8% of cases, malfunction, in 6.3-40% of cases, or infection in 0-15% of cases, with a noticeable higher risk of bacterial colonization after five days.

The optic nerve sheath surrounds the Optic Nerve (ON) and covers the optic subarachnoid space, which is connected to the intracranial subarachnoid space area. Changes in intracranial pressure are thus straightly transferred to the optic nerve sheath. Therefore, Optic Nerve Sheath Diameter (ONSD) is a non-invasive method of measuring Intracranial Pressure (ICP).

Longer ECLS periods and aortic cross-clamp times have been linked to more frequent CT detection of cerebral edema, according to prior investigationsAccording to prior investigations, long ECLS periods, and aortic cross-clamp times have been linked to more frequent CT (computer tomography) detection of cerebral edema. However, there is currently no information on the relationship between these time points and the ONSD determined by ultrasound.

The Primary Aim of this study was to identify the correlation between ONSD and ECLS time in newborns who get ECLS. Specifically, we tested the primary hypothesis that more ECLS time means more ONSD valuable over the perioperative period. Our secondary aim was to investigate the relationship between ONSD and aortic cross-clamp time and operation time and also, operation time and preoperative and intraoperative perioperative ONSD variation for the ECLS period.

Inclusion Criteria:

• ASA III or IV status newborn;
• Have surgery for transposition of great arteries (TGA).

Exclusion Criteria:

• All off-pump cardiac surgery;
• Recent history of cerebrovascular accident or intracranial hypertension due to any cause;
• History of increased ICP;
• Ophthalmological diseases capable of affecting optic nerve diameters.

The study population will occur newborns and will have cardiac surgery because of the surgery for transposition of great arteries (TGA). We worked on sample size analyses and found that it should be 22 patients at least to reach our actual power.