The doctors and nurses did not believe that Tomisa Starr was having trouble breathing.
Two years ago, Starr, 61, of Sacramento, California, was in the hospital because of a spike in her blood pressure. She has multiple chronic health conditions, including heart failure, and uses an oxygen tank at home.
But her request for supplemental oxygen while in the hospital was denied, Starr said, because readings from a pulse oximeter on her finger incorrectly indicated she was getting enough air on her own.
Starr, who is Black, said she told the health care team about research showing that the devices, which measure blood oxygen levels, may not work as well in people with darker skin and may make these patients appear healthier than they actually are. are.
Their reaction was shocking, according to Starr.
“The provider wanted to know, ‘Who told you that?’” she said. “Here I am in the hospital and have to defend myself as if I were in court.”
The skepticism Starr says he received from doctors about possible false pulse oximeter readings in black Americans is not unique.
“I lecture about this all the time to doctors who should know the research, and they are always impressed,” says Dr. Hugh Cassiere, an intensive care physician at South Shore University Hospital in New York. “This device has built-in racial disparities that have been ignored for years.” Cassiere is also leading a committee of independent experts, convened by the FDA, to investigate the pulse oximetry issue.
Potential problems with the measuring equipment have been known for decades. The FDA began developing guidelines for manufacturers to address the problems in 2013, but little has been done since then.
It wasn’t until the pandemic that the real dangers for Black patients became apparent. In 2021, the Food and Drug Administration warned about erroneous pulse oximeter readings on dark skin.
Last week, the FDA issued draft guidance for manufacturers to dramatically expand skin color varieties when testing their devices and show that they work equally for all skin pigments.
Historically, companies have not had to include a significant number of dark-skinned people in pulse oximeter studies.
“Frankly, the way we measured it was inconsistent and not done in a very valid or systematic way,” the head of the FDA’s Center for Devices and Radiological Health, Dr. Michelle Tarver, previously in an interview with NBC News. the draft guideline was released.
Cassiere expressed support for the new recommendations. “This is light years ahead of the 2013 guidelines,” he said.
The Food and Drug Administration does not approve or authorize all pulse oximeters on the market. Devices marketed for “general wellness” among hikers, cyclists or other athletes who want to estimate their blood oxygenation, for example, are unregulated and should never be used to diagnose or monitor health problems, the FDA said.
Pulse oximeters specifically intended for medical use fall under the purview of the FDA. It is these device manufacturers that the agency is targeting with its draft guidelines.
How pulse oximeters work
The gold standard and most accurate way to test whether someone has normal oxygen levels is to insert a needle into someone’s wrist and draw blood.
An arterial blood draw, as it is called, is invasive and painful. But it also gives doctors a vital clue as to how well a patient’s lungs are functioning, providing insight into which patients should be hospitalized and given supplemental oxygen or other treatment.
Pulse oximeters came onto the market in the 1980s as a simple and painless alternative. The device shines a light through the fingertip and searches for oxygen-rich blood. The more light absorbed, the better, in theory.
But that light is also absorbed by melanin, or pigment, in the skin. As a result, black and brown people are more likely to get pulse oximeter readings that show the oxygen saturation in their blood is higher than it actually is. That is, they may have trouble getting air despite normal pulse oximeter results.
The potential for racial disparities in pulse oximetry was first revealed in a study published 34 years ago. “That should have gotten the FDA’s attention,” Cassiere said.
It was largely ignored.
“I went to medical school at Howard University, which is a historically black university, and this was never brought up – never in training, never in practice,” says Dr. Noha Aboelata, founder and chief operating officer of Roots Community Health in Oakland, California. “I never knew anything about it until the first year of the pandemic.”
The light bulb moment
They were Dr. Thomas Valley and his colleagues at the University of Michigan who reignited rumors of the discrepancy in 2020 when they were swamped with Covid patients. The vast majority of the sickest patients were black.
“We started noticing that the numbers on the screen for pulse oximeters didn’t match what we were seeing in arterial blood,” Valley said. “We went from room to room to room and saw that these numbers didn’t look quite right.”
The team believed it was an anomaly caused by Covid – a brand new virus the world had never seen before.
“It wasn’t until a few months later that a light bulb went off,” Valley said. “This is not a Covid problem. This is a ‘skin color problem’.”
His team published its findings on racial bias in pulse oximeter readings in December 2020. It was this study, published in the prestigious New England Journal of Medicine, that Starr alerted her doctors to.
While there is no direct link between erroneous pulse oximeter readings and Covid deaths, additional research has found that people of color were more likely to die from Covid than white people.
The apparent differences go beyond Covid treatment.
The erroneous pulse oximeter readings for patients of color “may prevent Black patients from being candidates for advanced therapies” such as heart pumps or heart transplants, said Sarah Adie, associate director of innovation at the University of Michigan Health’s Frankel Cardiovascular Center. She co-authored a study published in 2024 that found that unreliable pulse oximeter readings could limit how Black patients with heart failure qualify for these potentially life-saving procedures.
Valley published additional research showing that a majority of pulse oximeter studies showed a bias toward people with darker skin tones.
Is skin pigmentation the ultimate problem with pulse oximeters? Maybe, maybe not.
“The question everyone wants to know now is: which devices work equally well, regardless of skin pigment?” said dr. Michael Lipnick, an anesthesiologist at the University of California, San Francisco. His team is analyzing results from more than fifty pulse oximeters in an attempt to answer that question.
Under close supervision, UCSF researchers attach a variety of pulse oximeters to study the participants’ fingers, then lower their oxygen levels to a point where the devices should signal a problem.
They expected that some devices – cheaper ones perhaps – would perform poorly overall.
That is not necessarily the case. “Some devices perform equally well regardless of skin pigment, while others do not,” Lipnick said. “We don’t understand why.”
Measures of how well a person circulates oxygenated blood through the body, called perfusion, may also play a role. That is not a condition specific to skin color. It may well take years for the team to understand the differences in pulse oximeter readings and why some perform poorly on people of color.
Delays in answers – or action – are not well received by doctors who treat predominantly black patients.
“We thought there was going to be some kind of drastic action,” said Aboelata of Oakland’s Roots Community Health. “Given the diversity of the country we have, how can we ever have a medical device that only works well on white skin?”
The Roots clinic has sued thirteen companies that make or sell pulse oximeters.
So far, Medtronic has agreed to warn hospitals in California that their devices may produce higher readings for patients with darker skin. Four other companies, Veridian Healthcare, Compass Health Brands, Gurin Products and Zewa, have agreed to add warning labels for California consumers.
But patients like Starr still rely on pulse oximeters, knowing they can produce erroneous results. She has no other choice, she said. “They’re all I have.”