FDA Warns That Pulse Oximeters Are Less Accurate on Darker Skin

Devices used to assess Covid-19 patients have serious limitations

New concerns about the accuracy of pulse oximeters have thrust the medical devices back into the spotlight. In the early days of the pandemic, they garnered a lot of attention because of their ability to detect some early warning signs of Covid-19.

These devices, which clip onto the index finger like a clothespin, use light to measure the level of oxygen in a person’s blood. A low oxygen reading may be an early sign that a person’s respiratory system is impaired due to Covid-19. Some people use these devices at home, but they’re also used in hospitals and doctors’ offices to decide what kind of care a person needs. That’s why a new report from the Food and Drug Administration is so concerning.

On February 19, the FDA released a document warning that pulse oximeters “may be less accurate in people with dark skin pigmentation.” The report is based on the results of a study published in the New England Journal of Medicine last December showing a disproportionate number of discrepancies in the blood oxygen measurements of Black people. The researchers, led by Michael Sjoding, MD, a pulmonary specialist at the University of Michigan Medical School, came to this conclusion by comparing measurements made by pulse oximeters with those made using a more accurate technique.

Dana G Smith wrote about Sjoding’s research in the Coronavirus Blog when it was published last year. “Skin pigment, specifically melanin, can interfere with light transmittance through the skin, making the reading less accurate,” she wrote. Sjoding raised concerns that an inaccurate measurement in an emergency setting — say, one that shows a person’s blood oxygen is higher than it actually is — could lead that person to be deprioritized for treatment or given less supplemental oxygen. The new FDA guidance aims to alert medical professionals and at-home users to the limitations of pulse oximeters so they can adjust their reliance on these devices accordingly.

Addressing the issue that led to limitations, however, will take a more coordinated effort. “Like so many drugs and medical devices,” Smith writes, “the pulse oximeter was developed and calibrated on white people, and, as a result, it does a poor job of reading information from people with darker skin tone.”

Read the full story in the Coronavirus Blog:

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A blog from Medium for Covid-19 news, advice, and commentary.

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