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

Chest. 2022 Apr;161(4):971-978. doi: 10.1016/j.chest.2021.09.025. Epub 2021 Sep 27.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Extracorporeal Membrane Oxygenation*
  • Humans
  • Hypoxia / diagnosis
  • Hypoxia / etiology
  • Oximetry / methods
  • Oxygen
  • Racism*
  • Respiratory Insufficiency* / diagnosis
  • Respiratory Insufficiency* / therapy
  • Retrospective Studies


  • Oxygen