NIRS MONITORING OF SPINAL CORD ISCHEMIA IN AORTIC SURGERY

pinal cord ischemia is a rare but severe complication associated with major surgical procedures, particularly in patients undergoing complex hemodynamic management. Early detection of impaired spinal cord perfusion remains challenging due to the lack of reliable, continuous, and non-invasive monitoring tools. Current monitoring strategies are indirect and often fail to provide timely information on regional perfusion changes.

Near-infrared spectroscopy (NIRS) is a non-invasive technique that measures regional tissue oxygen saturation (rSO₂) by analyzing the absorption of infrared light by oxygenated and deoxygenated hemoglobin. When applied to paraspinal muscles, NIRS may reflect local microcirculatory changes and potentially serve as a surrogate marker of spinal cord perfusion.

This is a single-center, prospective observational study designed to investigate the feasibility and clinical applicability of paraspinal NIRS monitoring in adult patients undergoing major noncardiac surgery requiring advanced hemodynamic monitoring. Patients will be monitored intraoperatively and during the early postoperative period using NIRS sensors placed bilaterally over the paraspinal regions.

Continuous rSO₂ measurements will be collected and integrated with routinely monitored hemodynamic variables, including arterial blood pressure, heart rate, and, when available, advanced parameters such as cardiac output and dynamic indices of fluid responsiveness. Data will be recorded at predefined time points and during relevant clinical events, such as induction of anesthesia, surgical phases, hemodynamic instability, and postoperative recovery.

The study aims to explore the physiological relationship between paraspinal rSO₂ and systemic hemodynamic changes, as well as to assess the feasibility, signal stability, and reproducibility of NIRS measurements in the perioperative setting. Particular attention will be given to identifying patterns of rSO₂ variation associated with hemodynamic fluctuations.

Data will be prospectively collected using standardized case report forms (CRFs). Data quality will be ensured through predefined data entry procedures, consistency checks, and periodic review of collected variables. All data will be anonymized prior to analysis.

A descriptive statistical approach will be used to summarize baseline characteristics and perioperative variables. Exploratory analyses will be conducted to evaluate the association between rSO₂ trends and hemodynamic parameters. Where appropriate, correlation analyses and regression models may be applied to investigate potential predictors of rSO₂ variation.

Given the exploratory nature of the study, no formal sample size calculation is required; however, enrollment is planned to ensure an adequate representation of the target population and to allow meaningful exploratory analysis.

This study is expected to provide preliminary evidence on the role of paraspinal NIRS monitoring as a non-invasive bedside tool for assessing tissue oxygenation and potentially guiding perioperative hemodynamic management strategies.

Inclusion criteria

Adult patients aged 18 years or older Patients scheduled for elective thoracic or thoracoabdominal aortic repair, including open, endovascular (TEVAR/FEVAR), or hybrid procedures Patients undergoing intraoperative paraspinal near-infrared spectroscopy (NIRS) monitoring Written informed consent obtained before enrollment

Exclusion criteria

Age under 18 years Emergency surgical procedures Pregnancy Pre-existing paraplegia or severe neurological impairment Skin lesions or conditions preventing correct placement of NIRS sensors Refusal or inability to provide informed consent