Assessment of regional cerebral oxygenation using near-infrared spectroscopy (NIRS) in lumbar spinal stabilization surgery

Lumbar spinal stabilization surgery carries a high risk of intraoperative cerebral oxygenation impairment due to prolonged operative time, blood loss, and the prone position. The aim of this study was to identify factors affecting regional cerebral oxygen saturation (rSO2) in this patient group and to evaluate the clinical value of monitoring with near-infrared spectroscopy (NIRS). Following ethical committee approval and patient consent, 85 patients undergoing three or more levels of lumbar spinal stabilization surgery at Süleyman Demirel University Research and Training Hospital, Department of Neurosurgery, between January 27 and July 27, 2025, were prospectively observed. Demographic data, hemodynamic parameters, respiratory parameters, entropy values, blood loss, blood product usage, duration of prone positioning, and intraoperative rSO2 values were recorded. A decrease in rSO2 of more than 20% from baseline or an absolute value below 50% was defined as the criterion for cerebral desaturation. Intraoperative rSO2 decline was observed in 41.2% of patients. No significant differences were found between rSO2 decline and sex, body mass index, or age. The duration of hypotension was significantly longer in the group with rSO2 decline (p=0.005). The use of erythrocyte suspension was higher in patients with rSO2 decline compared to those without (p=0.017). During the intraoperative period, positive correlations were observed between EtCO₂ and rSO2 from the 10th to the 100th minute of surgery, as well as between heart rate and rSO2 at multiple time points. A significant relationship between mean arterial pressure and rSO2 was observed only at the 80th, 90th, and 100th minutes. A negative correlation between entropy and rSO2 was detected solely at the 20th minute of surgery. Evaluation of the prone position revealed a statistically significant decrease in rSO2 values after transitioning from supine to prone (p=0.004). Our study demonstrates that cerebral oxygenation during lumbar stabilization surgery is particularly associated with the duration of hypotension and erythrocyte transfusion. Moreover, the positive correlations between EtCO₂ and heart rate with rSO2 indicate that cerebral oxygenation is strongly influenced by hemodynamic and respiratory parameters. Therefore, maintaining optimal intraoperative hemodynamic stability and effective management of blood loss is critical for preserving cerebral oxygenation. The findings support that close intraoperative monitoring of rSO2 is a valuable method for maintaining cerebral oxygen reserves.