Throughout the COVID-19 pandemic, pulse oximeters have been a common tool to measure blood oxygen levels through patients’ fingertips. However, experts at the Food and Drug Administration are now calling for changes to the devices based on growing evidence that they’re less accurate when used on darker skin.

The agency held a panel to discuss the issue this week, flagging yet another health disparity in need of attention. Experts on the panel called on the agency to improve how it tests the devices, as well as to apply better labeling to raise awareness about potential inaccuracies.

“The performance of medical devices needs to be well understood to mitigate any negative, unintended consequences for patients in different populations,” Richardae Araojo, FDA associate commissioner for minority health, said during the meeting.

Pulse oximeters aim to detect the color of blood by sending light through a person’s fingertip; red blood is linked to high oxygen levels, while blue or purple blood has lower oxygen. However, when the devices aren’t adjusted to non-white skin tones, absorption of the light may be different, causing inaccurate numbers.

In an executive summary, the FDA noted that a 2020 report found that pulse oximeters were less accurate in patients with darker skin tones. Since then, further studies have found that among people with darker skin, there’s an increased risk of missing hypoxemia diagnosis (or levels of blood oxygen that are too low), as well as delayed treatments and poorer patient outcomes.

Another study found that pulse oximeters over-estimated blood oxygen levels among Asian, Black and Hispanic patients. Citing the COVID-19 pandemic as an example, such an occurrence could lead to fewer patients getting the treatment they need.

These inaccuracies were also “associated with a systemic failure to identify Black and Hispanic patients who were qualified to receive COVID-19 therapy and a statistically significant delay in recognizing the guideline-recommended threshold for initiation of therapy,” the authors wrote.

The current FDA review of these devices typically relies on small studies that enroll few patients of color and they’re ultimately not the best examples of how pulse oximeters play out in real clinical settings.

The FDA panelists concluded that the agency should tighten up regulations in order to reduce the rate of inaccuracies from 3% to 2% or 1.5%.

Despite evidence showing racial bias in pulse oximeters existing for years, many manufacturers of the devices have defended their accuracy, arguing they meet current FDA standards.

But the tide may be turning on that front. 

At the FDA panel, several device manufacturers including Medtronic and Masimo, which develop pulse oximeters, admitted that the companies could do better. 

“We acknowledge more can be done to enhance accuracy and promote health equity,” chief medical officer of Medtronic’s Patient Monitoring Sam Ajizian said, according to STAT News.

An area where the FDA may struggle with control, however, lies in consumer pulse oximeters that are used at home — a trend that became more common during the pandemic. Pharmacies or online stores often sell pulse oximeters for $10 to $25, but they’re not as tightly regulated as medical-grade ones.

The panelists suggested the FDA could require manufacturers to have devices read a range of numbers, rather than a specific number that’s inaccurate and could mislead patients. 

They also recommended warning labels on devices that would urge people to seek medical attention if they have symptoms that are contradicted by a number on the oximeter that provides a false sense of security.