Pulse oximetry might overestimate blood oxygen in Black children

Key takeaways:

• Pulse oximetry readings in Black pediatric patients overestimated their blood oxygen levels compared with white peers.
• The results suggest a common medical device misleads clinicians.

A study found that pulse oximetry overestimated the blood oxygen levels in Black children more often than in white children, according to results published in in JAMA Pediatrics.

According to researchers from The Children’s Hospital of Philadelphia and University of Pennsylvania “several studies using large retrospective electronic health record data sets have found that pulse oximetry may overestimate actual blood oxygen levels in Black patients with hypoxemia more often than in white patients.”

“If true, a commonly used medical device could systematically mislead clinicians to undertreat hypoxemia in Black patients, a flaw with substantial implications for health care equity and outcomes,” they wrote in the new study.

The researchers compared values of arterial blood oxygen saturation (SaO₂) and pulse oximetry (SpO₂) in Black and white children, which they measured via a “pediatric cardiac catheterization laboratory, where SpO₂ is captured at 1-minute intervals in the [electronic health record] and is able to be linked to arterial blood gases processed immediately via co-oximeter.”

Among 774 patients aged between 1 and 17 years, 201 were identified as Black or African American. The authors noted that they included only cases where SaO₂ was measured from “a location reflective of systemic arterial saturation,” such as the descending aorta, femoral artery or systemic ventricle.

The researchers measured occult hypoxemia, defined as a measure of less than 92% SpO₂ as test for Sao₂ less than 88%, in their patients and then calculated bias and accuracy root mean square for pulse oximetry accuracy.

Ultimately, they found among patients with true hypoxemia, 12% of Black patients vs. 4% of white patients had false-negative results, whereas in patients with peripheral oxygen saturation levels suggesting normoxemia (SpO₂ 92%), 5% of Black patients vs. 1% of white patients had true hypoxemia (Sao₂ < 88%).

“Results of this cross-sectional study using data from a highly controlled clinical environment with tightly coupled Sao₂ and SpO₂ values suggest that pulse oximetry overestimated arterial oxygen saturation in children of Black or African American race,” the researchers wrote.

The authors also noted that discrepancies have been attributed to light absorption properties of melanin, which they said was an “imperfect proxy for skin pigmentation, with the inherent assumption that Black or African American patients had darker skin and more melanin than white patients.”

“Future studies in children should prospectively evaluate the association between SpO₂ and SaO₂ with reliable, direct measurement of skin pigmentation,” they wrote.

The study was accompanied by an editorial co-authored Keyaria D. Gray, DO, of the department of pediatrics at Duke University School of Medicine, and Hamsa L. Subramaniam, PhD, MPH, and Erich S. Huang, MD, PhD, of the San Francisco-based Verily Life Sciences.

“Although technologic refinement will undoubtedly yield solutions for the issue of bias in oximetry, inclusiveness must become a broad imperative in our regulatory frameworks — both in the initial approval of devices and in how we surveil real world application of technology,” they wrote. “It is virtually inevitable that unanticipated biases will arise, and we must develop systematic real-world processes to identify and correct them.”

References:

Gray KD, et al. JAMA Pediatr. 2023;doi:10.1001/jamapediatrics.2023.0077.

Ruppel HR, et al. JAMA Pediatr. 2023;doi:10.1001/jamapediatrics.2023.0071.