FDA reviews evidence pulse oximeters less accurate on people with darker skin

The Medical Devices Advisory Committee of the U.S. Food and Drug Administration (FDA) recently met to review the reported inaccuracy of pulse oximetry in patients with darker skin.

The meeting conducted on Tuesday was aimed at providing relevant insights and recommendations while the FDA conducts its evaluation of pulse oximeters’ accuracy and overall performance.

During the meeting, members of the Anesthesiology and Respiratory Therapy Devices Panel looked into the devices’ reported inaccurate readings associated with skin color. To get a better assessment of the devices, the panel heard from patients, regulators, researchers and medical device developers.

Adm. Richardae Araojo, FDA associate commissioner for minority health, argued that understanding the performance of such devices is relevant in mitigating “any negative, unintended consequences for patients in different populations.”

Pulse oximeters, which estimate the amount of oxygen in the blood without blood samples, are usually placed on a patient’s fingertip. They use light beams to “estimate the oxygen saturation of the blood and the pulse rate.” By detecting the color of the patient’s blood, the device determines if it is highly oxygenated (bright red) or less so (blue or purplish).

If not calibrated well for darker skin tones, the device may give off inaccurate readings as the skin’s pigmentation could affect how its sensor absorbs the light.

On a person with dark skin, the device could read that oxygen levels are normal when they are actually low.

Dr. Owais Durrani, an emergency medicine physician, said he sometimes conducts a “walking” pulse oximeter reading on patients with darker skin to make up for the possible discrepancy.

“So having a patient walk for like five minutes while having a pulse ox on, and usually if they are at higher risk, what will happen is, their oxygen numbers might drop further,” Durrani said.

While the walking test has allowed him to check whether a standard pulse oximeter reading has overestimated oxygen levels, he hopes a new device can provide a more accurate oxygen level reading for all of his patients regardless of their skin color.

Meanwhile, some participants in the meeting also questioned whether the discrepancies in pulse oximeter readings between people with dark and light skin are even significant.

Invented in 1974 by Japanese bioengineer Dr. Takuo Aoyagi, the devices have been known to produce inaccurate measurements in patients with dark skin since the 1980s.

The FDA also issued a premarket guidance in 2013, recommending pulse oximeter manufacturers have “a range of skin pigmentation” represented in their clinical studies of the devices, including at least two “darkly pigmented subjects or 15% of the study group, whichever is larger.”

The more frequent use of pulse oximeters during the start of the COVID-19 pandemic has placed more attention on the issue of inaccurate readings for dark-skinned patients.

In Feb. 2021, the FDA warned against the limitations and inaccuracy “under certain circumstances” of pulse oximetry use. The notice was based on a report published in the New England Journal of Medicine focusing on the racial bias in pulse oximetry measurements.

In the U.S., groups are already conducting research on how to address the biases by either canceling out melanin’s effect on existing devices or developing entirely different methods to read oxygen levels.

For now, panel members have made suggestions as to what the FDA can do to correct the inaccuracies.

“I would suggest that FDA might want to consider a labeling change,” Northwestern University professor Dr. Murad Alam, a panel member, said during the meeting.

“In the meantime, it would allow the FDA the ability to investigate these products and give consumers some guidance as to how to use them – and have some power to actually, at the very least, compel the manufacturers to convey that simplified and expanded labeling to patients who will in fact be using these to try to save their own lives,” he added.

Featured Image via Mufid Majnun

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