Pulse oximeters routinely overestimated levels of oxygen in the blood in darker-skinned Covid patients, leading to delays in treatment and hospital readmissions, according to a research article published on Thursday.

The research focused on the first years of the coronavirus pandemic, when patients overwhelmed hospitals. At the time, blood-oxygen levels were a key factor in deciding which patients wound up in limited hospital beds and received treatment.

Researchers from Baylor College, Johns Hopkins University and HCA Healthcare reviewed the cases of about 24,500 patients whose blood-oxygen levels were first measured with a pulse oximeter via a fingertip and whose blood was then drawn and tested to further examine those levels.

These researchers and other experts have raised concerns that the pulse oximeter readings via fingertip of people with darker skin pigment often show flawed results. The issue has already led to reviews by federal regulators, with some efforts underway to determine how to produce more accurate readings.
ImageA close-up view of a Black person’s hand resting on a blue hospital blanket, their ring finger in a pulse oximeter.

Why It Matters: The readings influence patient care.

Pulse oximeter readings are used routinely and help inform doctors in shaping medical care for any number of illnesses, including heart failure, sleep apnea and respiratory conditions. A normal reading for a patient in good health should be an oxygen saturation level in the blood of about 95 percent or higher. If the readings are falsely high, patients may look fine on paper — but they may not get the level of care they need.

The patients in the study released Thursday in JAMA Network Open were the ones researchers would have expected to have fared the best: Their doctors saw the need to take a more precise measure of their blood-oxygen levels. (Most patients’ fingertip reading is never double-checked with a blood draw.)

Patients with a fingertip pulse-oximeter reading of 94 percent or more but whose blood tests showed lower levels were deemed to have an unrecognized need for Covid therapy. Black patients were found to be nearly 50 percent more likely than white patients to have their condition go undetected. Hispanic patients were 18 percent more likely than white patients to have an unrecognized need.

Patients with unrecognized needs, regardless of race, experienced delays of roughly an hour that translated into a 10 percent higher risk of delayed Covid treatment. They were also more than twice as likely to be readmitted to the hospital.

The new study did not include patients whose oxygen levels might have mistakenly appeared normal via the pulse oximeter but had no follow-up blood test, and perhaps were sent home even though they might have been seriously ill.

“That’s the patient population that we’re really truly concerned about,” said Dr. Ashraf Fawzy, a study author who is a Johns Hopkins assistant professor and intensive care physician.
Background: Flaws could lead to great health disparities.

The Food and Drug Administration approves the type of fingertip pulse oximeter used in hospitals and sold by prescription. The agency issued a safety communication about the flaws in early 2021. And it held a hearing in the fall before an expert panel, with researchers outlining studies pointing to the role the device might have in deepening health disparities for patients with darker skin tone.

The agency approved those devices through its so-called 510(k) program, which clears devices that are similar to existing ones — with some additional scrutiny. The program has been criticized over the years because the standards for clearing devices are typically lower than those for the agency’s approval of new drugs.

During the hearing in November, the F.D.A. noted that the pulse oximeters sold over the counter are subject to even less oversight, prompting agency advisers to call for warnings to consumers who use the devices to gauge their own respiratory health.
What’s Next: The F.D.A. promises further review.

The F.D.A. has not announced a major change in how it oversees pulse oximeters, but it said on Thursday that it planned to publish a discussion paper to get feedback on the issue and convene another meeting with experts to discuss potential approaches.

“It is a high priority for the agency to ensure that oximetry device performance is equitable and accurate for all U.S. patients,” the agency said in a statement.

Some work has also begun to design a better pulse oximeter.

For now, though, Dr. Fawzy said doctors should trust their overall impression of a patient’s condition when taking a pulse-oximeter reading into account.

“It’s important for us to recognize that this device may lead to clinical decisions that are inaccurate,” he said, “or that we may be under-treating certain people or under-recognizing their needs.”