The small devices clamp onto a patient's finger and measure oxygen levels in blood. During the pandemic, they've been used by people at home and in hospitals to monitor COVID-19 patients as the virus attacks the lungs, often leading to a drop in oxygen levels.
"The devices may be less accurate in people with dark skin pigmentation," The U.S. Food and Drug Administration said in a statement on Friday.
Black patients are nearly three times as likely to have dangerously low blood oxygen levels go undetected by pulse oximetry compared with white patients, the FDA said, citing December research.
Pulse oximeters use infrared light beams to estimate the oxygen saturation of the blood and pulse rate, and darker skin pigment may absorb some of that light and alter results.
"Melanin is a primary light absorber in the skin, and it's going to absorb the light. This abounds more in individuals with darker skin," Dr. Panagis Galiatsatos, an assistant professor in the Division of Pulmonary & Critical Care Medicine at Johns Hopkins, told ABC News. "These devices were evaluated on a certain population. It doesn't take into account confounders like darker skin. We'd love to calibrate for darker skin variations -- it's just never been done before."
He said these devices appear to be just another example of health care disparities that result from when studies are too focused on a homogenous group.
Pulse oximeters are popular because they're a painless way to measure blood oxygen levels. Other factors that affect the accuracy of pulse oximeters include skin temperature and thickness, tobacco use and the use of fingernail polish.
Galiatsatos warned patients who use pulse oximeters at home to closely monitor their symptoms and call a doctor if they experience trouble breathing.
"It's crucial because if there's low oxygen that's untreated, it'll result in organ failure," he said.
The FDA is now reviewing the effects of skin pigmentation on the accuracy of these devices. Similarly, the Centers for Disease Control and Prevention updated its coronavirus clinical guidance to flag that skin pigmentation may adversely affect results.
However, this issue isn't new.
"Racial disparities in health care stem from a wide variety of factors, and it is particularly disturbing that racism may be embedded in key clinical tools," the lawmakers said in a statement.
They noted that sales of pulse oximeters skyrocketed during the pandemic even though studies from 2005, 2007 and 2020 found that the devices "provide misleading measures of blood oxygen levels to patients of color."
The health disparity comes as the pandemic already has disproportionately affected communities of color.
According to CDC data, Native Americans are nearly four times more likely to be hospitalized for COVID-19 compared with non-Hispanic whites. Black and Hispanic individuals are twice as likely to die from COVID-19 as white Americans and three times more likely to be hospitalized with the virus.