Background:
Delirium in the postoperative setting is of clinical importance due to increased morbidity
and long-term mortality. Near-infrared spectroscopy (NIRS) has been widely used to
measure regional oxygen saturation (rSO2) in brain tissue during cardiac surgery. We assessed retrospectively the association between duration and severity of perioperative
rSO2 decrease and the occurrence of delirium after cardiac surgery
Method: We enrolled 125 patients over 50 years of age, without previous psychiatric and neurological
history, who were scheduled for elective cardiac surgery between December 2019 and
December 2020 and among them, 83 patients with sufficient data on rSO2 in this study. Baseline rSO2 was measured before induction of anesthesia, throughout surgery and monitored continuously
up to 12 hours after operation. Baseline, minimal and average perioperative rSO2 values as well as areas under the curve (AUCs) at cutoffs of 25% and 50% of the preoperative
baseline values were calculated using the analytic tool. The presence of delirium
was assessed using the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU).
Results: Of 84 patients (65.57 ± 9.5 years old, 73% male, 27% female), 17 patients (20.4%)
presented with delirium during the ICU stay. They had severe absolute rSO2 decrease in comparison to the patients without delirium (p = 0.004). The duration of rSO2 reduction was significantly longer in patients with delirium at cutoffs of 25% (adjusted odds ratio [OR]: 6.35; 95% confidence interval [CI]: 2.02; 21.15, p = 0.001) and at cutoffs of 50% (adjusted odds ratio [OR]: 7.12; 95% confidence interval [CI]: 1.98; 25.57, p = 0.004). There was no significant difference regarding sex (p = 0.3), baseline rSO2 (p = 0.2), and average rSO2 (p = 0.2), but the patients with delirium were significantly older (p = 0.01), had longer duration of ventilation (p = 0.003), and had longer ICU stay (p = 0.034).
Conclusion: Perioperative cerebral oxygen saturation decrease was associated with postoperative
delirium occurrence after elective cardiac surgery, although our results need to be
confirmed in a properly sized sample of patients.