Pulse oximeters are inaccurate in people with darker skin, studies suggest. Now the FDA is reviewing.
A Food and Drug Administration panel discussed Tuesday several studies that found pulse oximeters may give less accurate readings for people with darker skin tones.
The studies found the devices, which are used to measure a person’s blood oxygen level, register higher oxygen level readings in people with darker skin tones, according to the FDA.
The devices were critical in making care decisions for COVID-19 patients at the height of the pandemic, leading many experts to believe that their unreliability contributed to the pandemic’s disproportionate toll on communities of color, which have seen higher mortality rates.
But studies that cast doubt on the the devices’ effectiveness on people with darker skin date back decades, long before the pandemic.
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COVID ‘brought everything to the forefront’
The problem had been identified as early as 1990 by Amal Jubran, a pulmonologist at Loyola University Medical Center in Illinois.
“It never got any traction, then the COVID pandemic brought everything to the forefront,” Jubran told USA TODAY.
That was in part because health care providers had a work-a-around available if they suspected someone’s oxygen levels were low despite healthy oximeter readings, according to Steven Gay, a clinical professor of internal medicine in the University of Michigan Medical School’s pulmonary and critical care division.
They could instead use an arterial blood gas test, which is considered the gold standard and requires drawing blood from the artery, Gay said.
But the pandemic overwhelmed hospitals and strained resources. Blood gas tests became scarce at many facilities, causing a greater reliance on the oximeters, Gay said.
“We were in a situation of doing the very best we could with what had available to us,” Gay told USA TODAY.
Study nudges FDA
It wasn’t until Gay and his colleagues treating patients at the University of Michigan Hospital early in the pandemic began to notice discrepancies between oximeter and blood gas test results in darker skinned patients.
“We realized, ‘oh my gosh,’ in the past there had been prior work showing that the pulse oximeter was less accurate in darkly pigmented patients,” Michael Sjoding, a fellow University of Michigan clinical professor, told USA TODAY. “What was described in these older studies might still be happening.”
That led to a 2020 study by Gay, Sjoding and their colleagues that found in one analysis that 11.7% of Black patients registered higher than accurate oxygen levels on pulse oximeters compared to 3.6% of white patients.
The study prompted the FDAto issue an advisoryin February of last year warning patients and providers to consider the limitations and “risks of inaccuracy” in pulse oximeters.
A 2022 study by Jubran and a colleague published in the peer-reviewed European-Respiratory Journalfound that inaccurate oximeter readings in darker skinned patients remained “unchanged” in 32 years.
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The Centers for Disease Control and Prevention recommended oxygen therapy for patients who registered oxygen saturation levels lower than 90%.
Patients in the University of Michigan study who received inaccurate oximeter readings posted saturation levels of 92% to 96%, when their levels were actually 88%, meeting the 90% or below threshold for oxygen therapy set by the CDC.
Pulse oximeters clasp around a finger tip and use light to measure oxygen in the blood. The general hypothesis is that darker skin pigmentation interferes with the passage of light, rendering inaccurate results, Jubran said. That’s why the FDA, for example, recommends removing any nail polish before using an oximeter.
The problem is believed to impact both FDA-approved oximeters used by healthcare professionals and over-the-counter versions available to the public. The FDA does not regulate the latter.
No timeline for recommendations
Tuesday’s meeting was just the first step in the FDA’s review process on the pulse oximeters.
After hearing from experts, the panel will deliberate how to develop testing oximeters to best ensure accuracy for all skin pigmentations, and whether pulse oximeters should be labeled with warnings about their limitations, according to an executive summary of the FDA panel meeting.
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Its task is to ultimately present recommendations for the FDA to vote on.
An FDA spokesperson told USA TODAY said the agency considered the issue a “high priority,” but offered no timeline on the process.
Sjolding said it was key to continue spreading awareness on the oximeters’ limitations across the medical community.
For consumers who might rely on oximeters at home, Sjolding said it may be wise to take note of your oxygen level before you get sick.
“If your reading is normally 98% and now it’s dropped down to 93%,” Sjolding said. “That’s a big drop and even though it may [appear to] be normal, it might not be normal.”