Pulse oximeters more likely to be inaccurate in people with darker skin

https://www.eurekalert.org/pub_releases/2020-12/mm-u-rbo121120.php

 

News Release 16-Dec-2020
Michigan Medicine - University of Michigan

 

Thousands of times a day, doctors and nurses use a small device called a pulse oximeter--which fits on the end of a patient's finger to measure the percentage of oxygen in the blood--to help them make vital treatment decisions. However, a new study by Michigan Medicine researchers finds that the pulse oximeter may be less accurate in Black patients than in White patients.

"These results really surprised all of us," says Michael Sjoding, M.D., assistant professor of internal medicine in the division of pulmonary and critical care medicine. As he and his colleagues cared for critically ill patients with COVID-19, a significant percentage of whom were Black, they noted a reoccurring discrepancy between readings from the pulse oximeter and a measurement from an arterial blood gas, which measures oxygen saturation directly through a blood test.


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Black patients were three times as likely to have a significant discrepancy in these readings. Twelve percent of the time, when Black patients had a pulse oximeter reading in this safe range, their actual saturation on an arterial blood gas was below 88%. In white patients, this discrepancy occurred three percent of the time.

"Many studies have examined health disparities between White and Black patients, with most determining Black patients have worse outcomes than White patients. What these studies often lack are reasons to explain these differences," says study co-author Thomas Valley, M.D., Assistant Professor in the Division of Pulmonary and Critical Care Medicine in the Department of Internal Medicine at the University of Michigan. "Our findings may provide one key explanation."

The findings raise a number of important questions about the management of patients in the hospital. Sjoding notes that there has been a departure from using the more invasive arterial blood gas measurements in favor of the simpler, less invasive pulse oximeter to determine whether a patient is getting enough oxygen. Knowing that pulse oximeter readings may be inaccurate will "absolutely affect therapy," he says. "I was caring for critically ill patients in the Intensive Care Unit when I first ran this analysis. The next day I started to rethink all my management strategies."

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