Impact of Racial Differences in Hypoxia Distribution on the Measured Prevalence of Occult Hypoxemia by Pulse Oximeters

Background

Racial differences in pulse oximeter accuracy increasingly have become recognized. However, previously published literature has not examined the extent to which underlying racial differences in levels of hypoxemia, such as those arising from differential testing, disease recognition, and treatment, may confound previously observed differences in pulse oximetry measurement.

Research Question

The presented study examined the extent to which underlying differences in arterial oxygen saturation (Sao₂) drive previously observed racial differences in pulse oximetry occult hypoxemia measurement.

Study Design and Methods

Analysis was completed as a secondary data analysis of two existing databases. Data were reanalyzed from the previously published Veterans Affairs (VA) Patient Database (2013-2019) and the Extracorporeal Life Support Organization (ELSO) registry (2019-2020). Patients included general ward and critically ill patients. We compared the measured burden of occult hypoxemia (ie, Sao₂ < 88%, with peripheral capillary oxygen saturation ≥ 92%) when standardizing for population-level distributions of Sao₂ vs when standardizing the sensitivity at each Sao₂.

Results

Black patients showed a higher likelihood of occult hypoxemia when compared with White patients in both data sources (Veterans Affairs Patient Database, 18.8% vs 14.9%; Extracorporeal Life Support Organization registry, 14.6% vs 7.0%). The distribution of Sao₂, to an extent, does change the measured occult hypoxemia rates; however, large racial differences were persistent after standardizing based on underlying Sao₂ distributions.

Interpretation

Underlying differences in Sao₂ distributions were observed in the analyzed data. Such differences point to ongoing differentials in care; however, even when accounting for Sao₂ distributions, differential detection of hypoxemia by race persisted in pulse oximeters in contemporary use.