Researchers warned an expert panel of the Food and Drug Administration on Tuesday that flawed readings on devices measuring oxygen levels in the blood — especially among Black and dark-skinned patients — might have contributed to deaths during the coronavirus pandemic. Panelists, in turn, urged the federal agency to raise accuracy standards and to alert doctors and consumers of the potential risks.

The devices that measure blood oxygen typically on the fingertip, known as pulse oximeters, can be cheap, small products sold over the counter or medical devices used in hospitals and clinics.

Decades before the pandemic, studies showed that they were less accurate on darker skin, often giving a healthy reading when blood tests showed more concerning levels.

But in recent years, experts said the flawed readings might have driven some of the racial and ethnic disparities exposed in studies reviewing access to Covid treatments. Authors of the studies emphasized that blood-oxygen levels were often a key factor in deciding who would receive certain medicines, oxygen therapies and even hospital beds at times when all were in short supply.

Dr. Amal Jubran, a pulmonary critical care doctor at Loyola Medicine in Chicago, one of the first physicians to identify the problem in 1990, testified on Tuesday that flawed readings were “hazardous” during the height of the pandemic.

They “most likely contributed to the several-fold greater number of deaths in Covid-19 in ethnic minority patients than in white patients,” Dr. Jubran told the panel.

The F.D.A. reviews prescription pulse oximeters and those used in hospitals under its so-called 510K program, which clears devices that are similar to existing ones — with some additional scrutiny. The over-the-counter versions are deemed “wellness” devices and are subject to virtually no agency oversight.

The accuracy concerns, which the agency flagged in 2021, led to a 10-hour meeting Tuesday of an F.D.A. advisory panel involving doctors and advisers. They did not formally vote on specific ways that the agency might address the issue, but several suggested measures like adding warnings to product labels and raising the bar manufacturers need to reach — in terms of correct readings — to get new devices approved. Doctors testifying to the panel also said studies gauging device performance on people with a range of skin tones and chronic medical conditions were needed.

Veverly Edwards, a community representative and the only African American on the panel of mainly white male doctors, called for manufacturers to be held accountable. She said Black people should have a sustained voice on the matter that also affects people of many ethnicities with dark skin.

“I guess my fear is that historically that the disparity in health care is like it never stops,” said Ms. Edwards, who is an assistant professor at the University of Memphis. “When you lump African Americans in with everyone else, we end up on the short end — because this started 30 years ago and here we are today addressing it.”

During the hearing, F.D.A. officials said the pulse oximeters used in hospitals were marketed based on studies of as few as 10 healthy people. And the devices that people buy online or at retail pharmacies are not scrutinized by the F.D.A.

Panelists agreed that the current rules were too lax for devices that had become a key driver of patient-care decisions, such as prescribing or ending the use of supplemental oxygen.

“That should be held to a very different standard,” said Dr. Hugh Cassiere, an adviser and critical care chief at North Shore University Hospital in New York. “We really need to tighten that up.”

Doctors who appeared before the panel cited a series of studies that showed how inaccurate readings from the devices used in hospitals affected people with darker skin during the pandemic and were associated with inadequate medical care.

One University of Michigan study found that the devices that squeeze the finger gave elevated readings in Black people when a blood test showed a lower rate, suggesting “hidden” hypoxemia, or significantly low blood oxygen. The discrepancy was found in nearly 12 percent of Black people and in nearly four percent of white people.

Dr. Ian Wong, a Duke University researcher, confirmed elevated levels of hidden hypoxemia in Black and Hispanic patients. He also told the panel that he found that all patients who had hidden hypoxemia had a risk of in-hospital death that was 70 percent higher than those with accurate readings.

Doctors at the Johns Hopkins University School of Medicine confirmed the disparity again and noted the result: Black and Hispanic patients were 29 and 23 percent less likely to be recognized as candidates for Covid treatments.

The studies were largely based on self-identified race, and researchers are still looking into the degree that melanin in the skin — which lends the darker pigmentation — affects pulse oximeter performance.

The findings underscore the importance of testing the devices on sick patients and those with a range of skin tones, said Dr. Eric Gartman, a Brown University assistant professor testifying for the American College of Chest Physicians. Currently those devices are tested in healthy people in a lab.

“We wouldn’t tolerate that in a medicine,” he said, “so I’m not sure we should tolerate that in a device, either.”

Dr. Jesse Ehrenfeld, president-elect of the American Medical Association and an anesthesiologist, testified that he wondered if the pulse oximeter he used on a patient Tuesday morning was going to be accurate.

“We need to take appropriate steps to remove the growing uncertainty around these devices and ensure the health and safety of the public,” he said.

Dr. Ehrenfeld said the F.D.A. should put specific warnings on devices that produce biased readings, make health providers aware of the limitations and increase testing of devices that were already cleared by the agency.

For the oximeters that people buy online or from retail stores, the lack of regulation is troubling, said one agency adviser, Dr. Murad Alam, a medicine professor at Northwestern University. People use them, he noted, to monitor oxygen levels at home and decide if they need urgent medical attention.

“This is a misclassification problem,” Dr. Alam said. “I don’t know how it happened, but this is not shampoo. So F.D.A. will need to find a way to regulate these.”

Advisers urged the agency to provide prominent warnings that the retail devices are not for medical use and are not approved by the F.D.A.

The agency said it was working with researchers from Stanford and the University of California, San Francisco, on real-world studies of device performance.