What’s the Deal With Pulse Oximeters?

Here’s what to know about devices that can measure blood oxygen saturation

Pulse oximeters measure the percentage of your red blood cells that are carrying oxygen by beaming different wavelengths of light into your finger after it’s clipped on. Photo: Smith Collection/Gado/Getty Images

People showing up at the ER with suspected Covid-19 tend to have an especially concerning symptom, explained emergency room physician Dr. Richard Levitan in the New York Times this month: Pneumonia caused by Covid-19 comes with dangerously low oxygen levels that sometimes go unnoticed. This symptom is known as “silent hypoxia,” wrote Levitan, “‘silent’ because of its insidious, hard-to-detect nature.”

The silence is worrying because it means people might be suffering from Covid-19 pneumonia without even knowing it. To detect silent hypoxia early enough to get treated for Covid-19 pneumonia, Levitan said people could use a home pulse oximeter, a small device for measuring blood oxygen saturation that can be purchased at a pharmacy.

That’s not to say that you should go out and buy one immediately. As one San Francisco physician noted in The Guardian, they “aren’t necessary” for people who are healthy and don’t have other Covid-19 symptoms. In Quartz, an interventional pulmonologist said there “is no good role” for a pulse oximeter if you’re a person who is healthy and doesn’t have supplemental oxygen on hand. Pulse oximeters are normally recommended for people with chronic lung disease who have to monitor…