Pulse oximeter readings more likely to be inaccurate in Black vs. white patients
New data published in The New England Journal of Medicine suggest potential racial bias in pulse oximetry measurement.
In two cohorts, including patients receiving supplemental oxygen in the hospital and patients in ICUs, Black patients had nearly three times the frequency of occult hypoxemia undetected by pulse oximetry compared with white patients, researchers reported.
“Given the widespread use of pulse oximetry for medical decision-making, these findings have some major implications, especially during the current COVID-19 pandemic,” Michael W. Sjoding, MD, assistant professor of internal medicine in the division of pulmonary and critical care medicine at the University of Michigan Medical School, and colleagues wrote. “Our results suggest that reliance on pulse oximetry to triage patients and adjust supplemental oxygen levels may place Black patients at increased risk for hypoxemia.”
The study included 1,609 adults (1,333 white, 276 Black) who received oxygen supplementation at the University of Michigan Hospital from January to July and 8,392 adults (7,342 white, 1,050 Black) in ICUs at 178 U.S. hospitals from 2014 to 2015. Researchers analyzed 10,789 pairs of measures of oxygen saturation by pulse oximetry and arterial oxygen saturation in arterial blood gas. Researchers tested for occult hypoxemia, defined as arterial oxygen saturation less than 88% despite an oxygen saturation of 92% to 96% on pulse oximetry.
Among the inpatients who received oxygen supplementation and had an oxygen saturation of 92% to 96% on pulse oximetry, researchers observed an arterial oxygen saturation less than 88% in 88 of 749 arterial blood gas measurements in Black patients (11.7%; 95% CI, 8.5-16) and in 99 of 2,778 measurements in white patients (3.6%; 95% CI, 2.7-4.7).
In the multicenter ICU cohort, results were similar and showed an arterial blood gas oxygen saturation less than 88% in 160 of 939 measurements in Black patients with an oxygen saturation of 92% to 96% on pulse oximetry (17%; 95% CI, 12.2-23.3) and in 546 of 8,795 measurements in white patients (6.2%; 95% CI, 5.4-7.1), according to the results.
The researchers noted that not all Black patients with a pulse oximetry reading of 92% to 96% had occult hypoxemia. “However, the variation in risk according to race necessitates the integration of pulse oximetry with other clinical and patient-reported data,” the researchers wrote.
The data raise important questions about the management of patients in the hospital, according to the researchers. Sjoding said in a press release 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 said in the release.
“I think we’re going to have to be more cautious about whether Black patients are truly getting that amount of oxygen they need,” Sjoding said in the release. “We may need to pay more attention to arterial blood gas results to confirm that the patient is getting enough oxygen.”
Inaccurate pulse oximeter readings may have implications in outpatient care as well, Sjoding said. Device makers may need to make additional changes to ensure that all patients receive an accurate reading, he said in the release.