Abstract:

Darker skin pigmentation appears to cause underestimation of regional oxygen saturation (rSO_2) 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 rSO_2 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 rSO_2 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 rSO_2 while controlling for various perioperative variables. The role of mean pre-bypass rSO_2 for predicting 30-day mortality was evaluated via multiple logistic regression, and the threshold for rSO_2 was selected by maximizing F1 score. There were 4267 patients included. Compared to Caucasian patients, the unadjusted difference in mean pre-bypass rSO_2 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 rSO_2 readings less than 2% were observed between racial groups. Mean pre-bypass rSO_2 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 rSO_2 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 rSO_2 is associated with increased 30-day mortality at a higher threshold than previously reported and was not significantly impacted by self-reported race.