A new observational study at Vanderbilt University Medical Center found that pulse-oximetry readings of patients with non-white skin may vary from commonly applied standards, raising concerns about a potential impact on critical care. The study is part of a continued focus at Vanderbilt on identifying and addressing disparities in healthcare.
The new study is a secondary analysis of the recently published PILOT (Pragmatic Investigation of Optimal Oxygen Targets) trial, which focused on oxygen titration in mechanically ventilated patients, and seeks to understand whether pulse oximetry is less accurate for patients with brown or black skin compared to white patients.
The laboratory blood gas (Sao2) test is considered oxygen titration’s “gold standard,” said Kevin P. Seitz, M.D., a clinical fellow at Vanderbilt and lead author of the study. Laboratory tests take time, however, “and sticking patients for arterial blood samples is painful,” he added.
The most common alternative is to use a pulse oximeter, which shines an LED light through the skin and provides a continually updated estimate of oxygen saturation. The device was widely introduced in the United States in the 1980s, and since that time some medical professionals have raised concerns about its accuracy for all patients, especially those with darker skin. As use of the devices became more common throughout the COVID 19 pandemic, further concerns were raised.
A December 2020 letter to the New England Journal of Medicine by Michael Sjoding, M.D. and others from the University of Michigan Medical School, entitled “Racial Bias in Pulse Oximetry Measurement,” first alerted the medical community and the FDA to the seriousness of the issue.
Seitz explains: “Their research letter concluded that if a patient who is Black has a normal pulse oximeter reading, they are more likely than a white patient to have a dangerously low oxygen saturation when you measure it with a lab test.”
As a result, researchers began re-examining data to confirm the pigmentation effect and to understand what might be done about it.
“There’s obviously a focus on reducing disparities in medicine right now,” said Matthew W. Semler, M.D., an assistant professor of medicine and biomedical informatics at Vanderbilt and lead investigator on the PILOT trial.