Association between Cerebral Oxygen Saturation with Outcome in Cardiac Surgery: Brain as an Index Organ

While both baseline regional cerebral oxygen saturation (rSO₂) and intraoperative rSO₂ decreases have prognostic importance in cardiac surgery, evidence is limited in patients who received interventions to correct rSO₂ decreases. The primary aim was to examine the association between rSO₂ values (both baseline rSO₂ and intraoperative decrease in rSO₂) with the composite of morbidity endpoints. We retrospectively analyzed 356 cardiac surgical patients having continuously recorded data of intraoperative rSO₂ values. Per institutional guidelines, patients received interventions to restore the rSO₂ value to ≥80% of the baseline value. Analyzed rSO₂ variables included baseline value, and area under the threshold below an absolute value of 50% (AUT50). Their association with outcome was analyzed with multivariable logistic regression. AUT50 (odds ratio, 1.05; 95% confidence interval; 1.01-1.08; p = 0.015) was shown to be an independent risk factor (along with age, chronic kidney disease, and cardiopulmonary bypass time) of adverse outcomes. In cardiac surgical patients who received interventions to correct decreases in rSO₂, increased severity of intraoperative decrease in rSO₂ as reflected by AUT below an absolute value of 50% was associated with a composite of adverse outcomes, implicating the importance of cerebral oximetry to monitor the brain as an index organ.