Pulse Oximeters Fail With Darker Skin Tones

Due to a widely used medical device’s inaccurate readings for darker skin tones, large numbers of Black and Latino patients were and continue to be subjected to critical delays in receiving potentially lifesaving treatments for COVID-19. A study made public in JAMA Internal Medicine reports that pulse oximeters, a common diagnostic tool used in COVID treatment, were prone to producing faulty results for Black, Latino, and Asian American patients—compared to consistently accurate reading for white patients. The main inaccuracy of the devices was in determining that patients of color were healthier than they actually were.

“Not only less accurate but, in particular, more optimistic,” said Dr. Tianshi David Wu, an assistant professor of pulmonary medicine at Baylor College of Medicine in Texas and co-lead author of the study. “In this study, we found that minority patients appeared healthier than they really were based on this bias in pulse oximetry.” Appropriate COVID care was therefore much harder to obtain, as health providers making treatment determinations based on oximeter readings might have thought their patients were exaggerating their intense symptoms. Patients of color were and are “having their need for treatment recognized at a later time than white patients,” as it was put by co-lead author Dr. Ashraf Fawzy, a professor of medicine at The Johns Hopkins University School of Medicine in Baltimore.

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Pulse oximeters assess the way the skin absorbs light in order to determine oxygen levels in the blood. Studies have shown that darker skin or even dark nail polish can render readings erroneous. Claims of racial bias in pulse oximeter functionality date back to the 1990s, and a report published in the early days of the COVID pandemic found that Black individuals are much more likely to receive false readings from the devices.