Faulty Pulse Oximetry Readings Delayed COVID-19 Care For Minority Groups

Pulse oximeters often showed inaccurate blood oxygen readings for Asian, Black, and Hispanic patients resulting in delayed COVID-19 care for these populations during the pandemic, according to a new study.

Published in JAMA Internal Medicine, the study included clinical data from five referral centers and community hospitals in the Johns Hopkins Health System. Data from patients with COVID-19 who self-identified as Asian, Black, Hispanic, or White were included in the study.

Researchers identified patients with occult hypoxemia, that is, patients with oxygen saturation levels of less than 88 percent in arterial blood (SaO2) and concurrent pulse oximetry (SpO2) readings between 92 percent and 96 percent. They then compared the proportion of patients with occult hypoxemia by race and ethnicity.

Of 7,126 patients with COVID-19, 1,216 Asian, Black, and Hispanic and 460 White individuals had 32,282 concurrently measured oxygen saturation levels in arterial blood and by pulse oximetry. Nineteen Asian, 136 Black, and 64 Hispanic patients had occult hypoxemia compared with 79 White patients.

Compared with White patients, pulse oximetry readings overestimated oxygen levels in arterial blood by an average of 1.7 percent among Asian, 1.2 percent among Black, and 1.1 percent among Hispanic patients.

"This was associated with systematic misclassification of patient oxygenation status based on racial or ethnic self-identification," the researchers wrote.

Around one-third of patients from each racial or ethnic minority group had at least one unidentified episode of hypoxia compared with fewer than one-fifth of White patients.

Further, the study shows that Black and Hispanic patients were less likely to be recognized as eligible for COVID-19 treatment compared with White patients. A total of 451 patients (23.7 percent) did not have their treatment eligibility recognized at all during the study, most of whom were Black (54.8 percent) and Hispanic (27.1 percent).

Among the 1,452 patients who were eventually deemed eligible for COVID-19 treatment, the median time until they were recognized as eligible was highest for Asian (7.7 hours) and Black patients (7 hours), followed by Hispanic patients (5 hours) and White patients (5.3 hours).

The researchers noted several limitations to their study, including that self-reported race and ethnicity, which is not usually collected in clinical settings, was used as a surrogate marker for skin tone, making it impossible for researchers to account for heterogeneity in skin tones within each group.

But the study does make a case for examining inaccuracies in pulse oximetry readings as a "potential explanation for disparities in COVID-19 outcomes." It may also have implications for monitoring and treating other respiratory illnesses.

Several studies have shown racial biases exist in pulse oximetry readings. Research published last year revealed greater variability in oxygen saturation levels measured by pulse oximetry in patients who self-identified as Black, followed by Hispanic, Asian, and White. The Food and Drug Administration even issued a safety communication about pulse oximetry use in February 2021.

In addition, a recent study shows that despite their widespread use during the COVID-19 pandemic, programs using pulse oximeters to monitor COVID-19 patients at home produced similar benefits to programs that did not.