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

Abstract

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.