Temporal Dynamics of Perioperative Redox Balance and Its Association with Postoperative Delirium After Cardiac Surgery

Postoperative delirium (POD) is a neurocognitive complication that commonly occurs after cardiac surgery. Despite the association of POD with increased morbidity and mortality, reliable perioperative biomarkers for predicting POD remain scarce. This retrospective observational study investigated whether temporal changes in perioperative redox balance are associated with POD development. Fifty adult patients who underwent elective cardiac surgery at Osaka University Hospital were included. Serum levels of derivatives of reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP) were measured preoperatively, immediately after intensive care unit admission, and on postoperative days 1-4. POD was assessed twice daily using the Intensive Care Delirium Screening Checklist (ICDSC), with an ICDSC score of ≥3 indicating delirium. POD occurred in 18 (36%) out of 50 patients. Compared with non-POD patients, those with POD exhibited higher preoperative d-ROMs levels, a lower BAP/d-ROMs ratio, a transient postoperative increase in BAP, and a relatively higher BAP/d-ROMs ratio during the early postoperative period. Preoperative d-ROMs levels showed a positive correlation with the maximum ICDSC score. In conclusion, perioperative redox dynamics are associated with POD risk and severity. Redox-related markers, particularly d-ROMs, may have potential as biomarkers for identifying patients at higher risk of POD after cardiac surgery, and their clinical utility warrants further prospective validation.