Racial Bias in Pulse Oximetry Measurement Among Patients About to Undergo Extracorporeal Membrane Oxygenation in 2019-2020: A Retrospective Cohort Study

Abstract

Background: Pulse oximeters may produce less accurate results in non-White patients.

Research question: Do pulse oximeters detect arterial hypoxemia less effectively in Black, Hispanic, and/or Asian patients than in White patients in respiratory failure and about to undergo extracorporeal membrane oxygenation (ECMO)?

Study design and methods: Data on adult patients with respiratory failure readings 6 h before ECMO were provided by the Extracorporeal Life Support Organization registry. Data was collected from 324 centers between January 2019 and July 2020. Our primary analysis was of rates of occult hypoxemia-low arterial oxygen saturation (Sao₂ ≤ 88%) on arterial blood gas measurement despite a pulse oximetry reading in the range of 92% to 96%.

Results: The rate of pre-ECMO occult hypoxemia, that is, arterial oxygen saturation (Sao₂) ≤ 88%, was 10.2% (95% CI, 6.2%-15.3%) for 186 White patients with peripheral oxygen saturation (Spo₂) of 92% to 96%; 21.5% (95% CI, 11.3%-35.3%) for 51 Black patients (P = .031 vs White); 8.6% (95% CI, 3.2%-17.7%) for 70 Hispanic patients (P = .693 vs White); and 9.2% (95% CI, 3.5%-19.0%) for 65 Asian patients (P = .820 vs White). Black patients with respiratory failure had a statistically significantly higher risk of occult hypoxemia with an OR of 2.57 (95% CI, 1.12-5.92) compared with White patients (P = .026). The risk of occult hypoxemia for Hispanic and Asian patients was equivalent to that of White patients. In a secondary analysis of patients with Sao₂ ≤ 88% despite Spo₂ > 96%, Black patients had more than three times the risk compared with White patients (OR, 3.52; 95% CI, 1.12-11.10; P = .032).

Interpretation: Compared with White patients, the prevalence of occult hypoxemia was higher in Black patients than in White patients about to undergo ECMO for respiratory failure, but it was comparable in Hispanic and Asian patients compared with White patients.

Keywords: ECMO; hypoxemia; oxygen; pulse oximetry; racial bias.

Graphical abstract

Figure 1

Flow diagram for the creation of study cohort. Racial and ethnic categories (as defined by the Extracorporeal Life Support Organization) with fewer than 400 observations were excluded. The excluded groups were as follows: Middle Eastern or North African (n = 131), Native American (n = 55), Native Pacific Islander (n = 10), Multiple (n = 149), Other (50), and Unknown (n = 125). ECMO = extracorporeal membrane oxygenation; Sao₂ = arterial oxygen saturation; Spo₂ = peripheral oxygen saturation.

Figure 2

Difference between Spo₂ and Sao₂ against the mean of Sao₂ across different races and ethnicities. Bland-Altman plots were produced using the following command in Stata version 16.1 [blandaltman Spo₂ Sao₂]. See e-Appendix 1 for complete analytic code. Sao₂ = arterial oxygen saturation; Spo₂ = peripheral oxygen saturation.

Figure 3

Prevalence of Sao₂ of ≤ 88% despite Spo₂ of 92% to 96% across different races and ethnicities. Sao₂ = arterial oxygen saturation; Spo₂ = peripheral oxygen saturation.