Pulmonary Mechanics and Cerebral Oxygenation During Prone Lumbar Disc Surgery

This prospective observational study aims to evaluate the relationship between changes in respiratory mechanics and cerebral oxygenation in adult patients undergoing elective lumbar disc surgery in the prone position under general anesthesia. Cerebral regional oxygen saturation will be monitored using bilateral frontal near-infrared spectroscopy (NIRS), while respiratory parameters including tidal volume, respiratory rate, peak airway pressure, plateau pressure, positive end-expiratory pressure, and dynamic compliance will be recorded from the anesthesia ventilator. Measurements will be obtained at predefined time points before and after positioning the patient prone and after returning to the supine position at the end of surgery. No changes will be made to anesthesia, ventilation, medication doses, or surgical management for research purposes. All clinical care will be provided according to routine practice by the responsible anesthesia team. The study will investigate whether changes in respiratory mechanics during prone positioning are associated with changes in cerebral regional oxygen saturation.