Regional cerebral oximetry is consistent across self-reported racial groups and predicts 30-day mortality in cardiac surgery: a retrospective analysis

J Clin Monit Comput. 2021 Apr;35(2):413-421. doi: 10.1007/s10877-020-00487-x. Epub 2020 Feb 21.

Abstract

Darker skin pigmentation appears to cause underestimation of regional oxygen saturation (rSO2) for certain cerebral oximetry devices. This presents a risk of triggering unindicated interventions and may limit its utility for predicting adverse outcomes. Our goal was to quantify the impact of self-reported race on oximetry measurements during cardiac surgery and elucidate whether race has a mediating role in the association of rSO2 with mortality. Data was extracted from our department's data warehouse for adult patients who underwent on-pump cardiac surgery between June 2014 and June 2018. Intraoperative rSO2 was recorded every 15 s throughout all cases. After grouping patients by self-reported race, multiple linear regression modeling was utilized to assess the association between race and mean pre-bypass rSO2 while controlling for various perioperative variables. The role of mean pre-bypass rSO2 for predicting 30-day mortality was evaluated via multiple logistic regression, and the threshold for rSO2 was selected by maximizing F1 score. There were 4267 patients included. Compared to Caucasian patients, the unadjusted difference in mean pre-bypass rSO2 was - 0.6% (95% CI - 1.3 to 0.04) for African American patients, - 1.8% (- 2.7 to - 0.9) for Asian patients, 0.1% (- 0.8 to 1.0) for Hispanic patients, - 1.6% (- 3.0 to - 0.4) for Indian/South Asian patients, and - 1.4% (- 3.7 to 0.9) for Pacific Islander patients. After adjusting for perioperative variables, differences in rSO2 readings less than 2% were observed between racial groups. Mean pre-bypass rSO2 under 63% was an independent predictor of higher 30-day mortality risk (OR: 2.86, CI 1.39 to 5.53, p = 0.003), and the interaction variable between rSO2 and race was not statistically significant (p = 0.299). Cerebral oximetry measurements are more consistent across racial groups than previously reported, supporting its utility for intraoperative monitoring and risk stratification. Pre-intervention rSO2 is associated with increased 30-day mortality at a higher threshold than previously reported and was not significantly impacted by self-reported race.

Keywords: Cardiac anesthesia; Mortality; Near-infrared spectroscopy; Oximetry; Risk assessment; Skin pigmentation.