Pulse Oximeters Infrequently Tested by Manufacturers on Diverse Sets of Subjects

Manufacturers increasingly but still infrequently follow Food and Drug Administration guidance that recommends testing pulse oximeters on participants with a range of skin pigmentations, according to a new study led by researchers at the Johns Hopkins Bloomberg School of Public Health.

The FDA made the recommendation in 2013, following reports that pulse oximeters—devices that measure blood-oxygen levels by shining light through the skin—can be less accurate when used on people with dark skin and that undetected low oxygen levels are more common in non-white patients. This puts patients with darker skin at risk for missed symptoms and potential misdiagnoses.

In the new study, the researchers analyzed publicly available FDA clearance summaries from manufacturers of FDA-regulated pulse oximeters before and after the FDA’s guidance. They found only a quarter of the summaries since 2016 include language suggesting compliance, up from just 4.1% before the guidance was issued.

The FDA ‘clears’ medical devices that are sufficiently similar to devices that have already been approved by the FDA. Pulse oximeters intended for use in medical decision making or monitoring, whether at home or in a clinical setting, go through this FDA pathway. They became even more widely used during the COVID pandemic, as many people bought them for home use.

The findings are described in a peer-reviewed research letter published online December 30 in JAMA. On January 6, the FDA announced updated draft guidance for manufacturers on pulse oximeters. The FDA’s new draft guidance includes recommendations for manufacturers to include larger numbers of participants with a range of skin tones in their testing.

“Our findings underscore the limits of voluntary guidance alone for solving bias in pulse oximeters,” says study lead author Kadija Ferryman, PhD, an assistant professor in the Bloomberg School’s Department of Health Policy and Management and the Berman Institute of Bioethics. “The FDA’s new draft guidance is a step in the right direction, but others, including manufacturers, health care organizations, and other organizations committed to patient safety can contribute to addressing this bias.” 

In a companion Viewpoint published December 30 in JAMA, Ferryman and colleagues describe bias in pulse oximetry as a “wicked problem” with no easy solutions. 

Pulse oximeters gauge the proportion of oxygen-carrying red blood cells in a patient’s bloodstream by shining light of two wavelengths through the patient’s finger and comparing the differential absorbance of those wavelengths. Now standard tools in clinical settings, pulse oximeters are especially useful in monitoring and assessing the care needs of patients who may have dangerously low levels of blood oxygenation (hypoxemia) due to heart or lung conditions, including COVID-19.

Clinicians since the 1990s have been reporting that pulse oximeters often give false readings in people with dark skin. Such reports eventually led the FDA to issue a guidance in 2013 for oximeter manufacturers that they include in their studies “subjects with a range of skin pigmentations, including at least two darkly pigmented subjects or 15% of your subject pool, whichever is larger.” 

In their new analysis, Ferryman and colleagues examined manufacturers’ adherence to this recommendation. The researchers searched an FDA database containing the agency’s product clearance summaries for pulse oximeters, identifying and retrieving a total of 767 oximeter clearance summaries for the period 1996-2024. They then compared the frequency of summaries containing any of 17 search terms relating to race, ethnicity or skin color in the pre-guidance period 1996–2012, the period 2013–2015 around the time of the guidance, and the post-guidance period from 2016 to 2024.

They found that 17 of the 412 documents from the pre-guidance period (4.1%), 12 of 87 (13.8%) from around the guidance period, and 67 of the 268 documents (25.0%) from the post-guidance period contained one or more of their search terms. This suggested that the FDA’s guidance did have an impact, but only a small one—the vast majority of post-guidance summaries made no reference to the skin tone issue or to tests with diverse subjects.

Examining the search term-containing summaries, the researchers also observed that they broadly lacked a standardized framework for assessing skin tone variation, often describing test subjects’ skin simply as “dark” or “light,” or making reference only to their ethnic or racial background.

The draft guidance issued on January 6 is open for comments until March 10.

“Adherence to FDA Guidance on Pulse Oximetry Testing Among Diverse Individuals, 1996–2024” was written by Kadija Ferryman, Deidra Crews, Emmanuel Drabo, Theodore Iwashyna, Odia Kane, and John Jackson.

“Addressing Racial and Ethnic Bias in Pulse Oximeters—A Wicked Problem” was written by Carmel Shachar, Emmanuel Drabo, Theodore Iwashyna, and Kadija Ferryman.

The study was funded by a Nexus Research Award from Johns Hopkins University. 

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Media contacts: Kate Sam ksam2@jh.edu or Kris Henry khenry39@jhu.edu