Story at a glance
- New research sheds light on the widespread discrepancies of pulse oximeter accuracy among patients of color.
- The devices are used in both veterans and commercial hospitals.
- Authors caution increased clinician awareness is currently the only solution to mitigate the problem.
Throughout the COVID-19 pandemic, calls for increased vigilance when using pulse oximeters to measure blood oxygen levels were common, as research indicated these devices may not be as accurate among individuals with darker skin.
However, some argued the inaccurate readings might be contained to extremely sick individuals in intensive care units and that low blood pressure or other factors may play a role in the discrepancies.
To better determine the pervasiveness of inaccurate readings, researchers at the University of Michigan conducted a study on patients within the Veterans Health Administration, the nation’s largest integrated health system. Pulse oximeters are used to measure low blood oxygen or hypoxemia, a hallmark of severe COVID-19 and certain lung or heart conditions.
Data from more than 100 hospitals revealed that within this system alone, there could have been more than 75,000 instances each year where low blood oxygen was missed in a Black veteran but might have been caught if the devices worked as well as they did in white patients, explained lead study author Valeria Valbuena in a press release.
Missed hypoxemia is associated with worsened disability and higher mortality.
“That has to mean something to someone, at the very least to ensure our veterans are getting the care they deserve after serving their country,” Valbuena continued. “It is just not fair that we are using devices that don’t work as well for Black veterans as for white veterans.”
Researchers compared blood oxygen measurements taken via pulse oximeter with those of arterial oxygen saturation, measured in arterial blood gas, among patients not in intensive care.
Electronic medical record data from 2013 to 2019 were assessed. Each patient’s readings were taken within 10 minutes of each other.
Overall “Black patients had higher odds than white patients of having occult hypoxemia [unrecognized low oxygen levels] noted on arterial blood gas but not detected by pulse oximetry,” researchers wrote. “This difference could limit access to supplemental oxygen and other more intensive support and treatments for black patients.”
White veterans had a 15.6 percent probability of occult hypoxemia, compared with 16.2 percent in Hispanic or Latino veterans, and 19.6 percent in Black veterans.
In patients who received one reading earlier in the day and an additional reading later, those made in white patients were also more consistent with each other than those from Black patients, suggesting the same trust cannot be placed in pulse oximeter readings over time for Black patients, said co-author Thomas S. Valley in a statement.
“Even if the pulse [oximeter] agreed with the earlier blood draw, later pulse [oximeter] measurements might miss low blood oxygen levels in Black patients,” Valley added.
In an effort to address the discrepancies, the Food and Drug Administration plans to hold a meeting of the Medical Devices Committee later in 2022. Currently, increased awareness of the issue among providers remains the only option of mitigating this problem.
Because the Veterans Health Administration uses the same pulse oximeters as commercial hospitals, authors caution results are likely generalizable to the wider public.