High Cerebral Oxygen Saturation Levels During One-Lung Ventilation Predict Better Cognitive and Clinical Outcomes After Thoracic Surgery: A Retrospective Observational Study

<b>Background:</b> Cerebral desaturation during one-lung ventilation (OLV) in thoracic surgery has been associated with postoperative cognitive dysfunction (POCD). While the adverse effects of low intraoperative regional cerebral oxygen saturation (rScO₂) are well documented, the potential clinical value of maintaining supranormal rScO₂ levels has not been thoroughly studied. <b>Methods:</b> We conducted a retrospective observational study based on a previously collected cohort from a tertiary university hospital. Adult patients undergoing elective thoracic surgery between January 2019 and December 2022 were included, provided they received lidocaine either intravenously or via a paravertebral block as part of a standardized anesthetic protocol. Patients were divided into the following two groups based on their mean INVOS values 30 min into OLV: those with rScO₂ ≥75% (H-INVOS group) and <75% (L-INVOS group). Intraoperative physiological variables, inflammatory biomarkers, cognitive function via the Mini-Mental State Examination, and postoperative outcomes were analyzed. <b>Results:</b> The H-INVOS group exhibited significantly higher preoperative lung function, higher PaO₂ and PaCO₂ values during OLV, and higher hemoglobin concentrations across all timepoints. They also demonstrated better preservation of cognitive function, lower IL-18 expression at 24 h postoperatively, and shorter hospital stays. There were no statistically significant differences in intraoperative hemodynamics or ventilatory mechanics.