Racial and Ethnical Discrepancy in Hypoxemia Detection in Patients on Extracorporeal Membrane Oxygenation

Objective: To determine whether there is racial/ethnical discrepancy between pulse oximetry (SpO) and oxygen saturation (SaO) in patients receiving extracorporeal membrane oxygenation (ECMO).

Methods: This was a retrospective observational study at a tertiary academic ECMO center with adults (>18 years) on venoarterial (VA) or venovenous (VV) ECMO. Datapoints were excluded if oxygen saturation ≤70% or SpO-SaO pairs were not measured within 10 minutes. The primary outcome was the presence of a SpO-SaO discrepancy between different races/ethnicities. Bland-Altman analyses and linear mixed-effects modeling, adjusting for prespecified covariates, were used to assess the SpO-SaO discrepancy between races/ethnicities. Occult hypoxemia was defined as SaO <88% with a time-matched SpO ≥92%.

Results: Of 139 patients receiving VA-ECMO and 57 patients receiving VV-ECMO, we examined 16,252 SpO-SaO pairs. The SpO-SaO discrepancy was greater in VV-ECMO (1.4%) versus VA-ECMO (0.15%). In VA-ECMO, SpO overestimated SaO in Asian (0.2%), Black (0.94%), and Hispanic (0.03%) patients and underestimated SaO in White (-0.06%) and nonspecified race (-0.80%) patients. The proportion of SpO-SaO measurements considered occult hypoxemia was 70% from Black compared to 27% from White patients ( < .0001). In VV-ECMO, SpO overestimated SaO in Asian (1.0%), Black (2.9%), Hispanic (1.1%), and White (0.50%) patients and underestimated SaO in nonspecified race patients (-0.53%). In linear mixed-effects modeling, SpO overestimated SaO by 0.19% in Black patients (95% confidence interval, 0.045%-0.33%,  = .023). The proportion of SpO-SaO measurements considered occult hypoxemia was 66% from Black compared with 16% from White patients ( < .0001).

Conclusions: SpO overestimates SaO in Asian, Black, and Hispanic versus White patients, and this discrepancy was greater in VV-ECMO versus VA-ECMO, suggesting the need for physiological studies.