Postoperative delirium remains a common complication after cardiac surgery in high-risk patients and has been associated with prolonged intensive care unit length of stay, overall morbidity, and mortality. It has been proposed that cerebral hypoperfusion is an important etiological component. In the present study, we retrospectively queried intraoperative near-infrared spectroscopy measurements of regional cerebral oxygen saturations (rSO₂) during adult cardiac surgical procedures to examine the association between rSO₂ desaturations and postoperative delirium.

Retrospective observational cross-sectional study.

Single tertiary care institution.

Patients aged 18 and older undergoing cardiac or open ascending thoracic aortic surgery from January 2016 through April 2023 were eligible; 3,696 patients were included in the analysis.

As per departmental protocol, bilateral rSO₂ probes were applied to the patients’ forehead before induction of anesthesia. The first 5 minutes of rSO₂ measurements were averaged and used as their baseline measurements. The total intraoperative duration of rSO₂ measurements that were either 20% below baseline or below an absolute value of 50% and the total time in either category were determined. Postoperative delirium was assessed using the Confusion Assessment Method for Intensive Care Unit during the postoperative period. Age, cerebral vascular disease, preoperative cognitive impairment, dexmedetomidine use, and durations of cardiopulmonary bypass and bispectral index values less than 40 were associated with delirium. Neither baseline rSO₂ nor any of the perioperative rSO₂ desaturation incidences or durations were associated with postoperative delirium.

Neither baseline nor intraoperative near-infrared spectroscopy–measured cerebral rSO₂ parameters were associated with postoperative delirium. Additional future studies are necessary to further define the value of perioperative cerebral rSO₂ monitoring for the prevention of delirium after cardiac surgery.