Pulse Oximeter Devices Have Higher Error Rate in Black Patients--New study

Pulse oximeters are one of the most commonly used tools in medicine. The small devices, which resemble a clothespin, measure blood oxygen when clipped onto a fingertip, and they can quickly indicate whether a patient needs urgent medical care.

Health providers use them when they take vital signs and when they evaluate patients for treatment. Ever since the pandemic started, doctors have encouraged patients with Covid to use them at home.

But in Black patients, the devices can provide misleading results in more than one in 10 people, according to a new study.

The findings, which were published last week as a letter to the editor of a top medical journal, sent ripples of dismay through the medical community, which relies heavily on the devices to decide whether to admit patients or send them home. ...

“I think most of the medical community has been operating on the assumption that pulse oximetry is quite accurate,” said Dr. Michael W. Sjoding, an assistant professor of internal medicine at the University of Michigan Medical School and lead author of the new report, which appeared in the New England Journal of Medicine. “I’m a trained pulmonologist and critical care physician, and I had no understanding that the pulse ox was potentially inaccurate — and that I was missing hypoxemia in a certain minority of patients.” ...

Dr. Philip Bickler, the director of the hypoxia research laboratory at University of California, San Francisco, which tests the performance of pulse oximeters, said the simplest way to explain the inaccuracies in patients with darker skin is that the pigment “scatters the light around, so the signal is reduced. It’s like adding static to your radio signal. You get more noise, less signal.” (Dark nail polish also reduces the accuracy, as do cold fingers.) ...