Blood oxygen monitors miss symptoms of COVID-19 more often in patients of color


Blood oxygen monitors said hospitalized Asian, Black and Hispanic COVID-19 patients had higher blood oxygen levels than they actually were, according to a new study. Oxygen levels are an important indicator of the severity of a person’s COVID-19 case and the medications they are eligible for – and this overestimation meant it took black and Hispanic patients longer to get treatment necessary.

Pulse oximeters, the standard method used by clinics and hospitals to measure blood oxygen, work by sending red and infrared light through the fingertip and measuring the amount that is reflected back. (Hemoglobin, the blood protein that carries oxygen, absorbs more infrared light when it carries oxygen). For years, studies have shown that these devices don’t work as well on people with darker skin tones.

In this new study published in the journal JAMA internal medicine, a research team examined patients with COVID-19 in the Johns Hopkins Health System between March 2020 and November 2021. Just over 1,200 patients had oxygen levels checked by both heart rate oximeters and pulse and a more accurate blood test. In about 30% of Asian, Black, and Hispanic patients, the blood test showed low blood oxygen levels while the pulse oximeter indicated the levels were normal. This was only the case for 17% of white patients.

In a larger group of more than 6,600 patients, the research team found 1,903 patients in whom a model showed their oxygen levels would have dropped before the pulse oximeter showed it. In this group, black and Hispanic patients were more likely to have had delays in receiving treatments like remdesivir (which most hospitals only gave to patients with oxygen levels below 94%) or dexamethasone (which most hospitals only gave to patients on supplemental oxygen). ).

Of this group, 451 patients were never reported as eligible for treatment. More than half of these patients were black. It took black patients who eventually received treatments about an hour longer than white patients to be flagged as eligible.

Other research in recent years has come to similar conclusions. A study published in November 2021, for example, also showed that discrepancies between oxygen levels measured on a blood test and a pulse oximeter were more likely for nonwhite patients in hospitals than for white patients. Patients with this discrepancy were more likely to have organ problems and die in hospital. The Food and Drug Administration warned in February 2021 that pulse oximeter readings have “limits” and that skin color can affect readings.

But despite the well-documented shortcomings, there have been no major steps to correct the bias, the researchers wrote in an editorial accompanying the new study. “Hospitals and practitioners continue to purchase and use these devices despite their inaccuracy for non-white patients,” they said. It’s not an easy problem to fix, and pulse oximeters are a less accurate measure of blood oxygen overall. But hospitals and regulators should push to only allow devices that work the same on all skin tones, and doctors can adjust their treatment practices to recognize potential errors in their non-white patients.

“While device measurement error is real and based solely on optics, the decision to do nothing about a faulty device is a human decision, and one that can and should be corrected,” they said. they wrote.


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