Fingertip sensors for measuring blood oxygen have errors for people with darker skin

Rogan was immediately skeptical of the accuracy of the reading due to his mother’s history of chronic illnesses. He said he felt she needed oxygen because of the way she was breathing.

Rogan took his concerns to his mother’s cardiologist, whom he considers a friend of the family. But the doctor still hasn’t given her mother oxygen, pointing to the pulse oximeter reading.

It wasn’t until the cardiologist went on vacation that Rogan found another doctor willing to provide the oxygen treatment. Rogan said his mother immediately started feeling better. However, she is still recovering today.

“It’s something that I think needs to be carefully considered and evaluated by companies that make pulse oximeters,” said Rogan, who practices in Atlanta. “Why isn’t it working properly?” »

A pulse oximeter works by using a beam of light to detect oxygen carried in red blood cells after being attached to the fingertip or ear. It provides a reading of the oxygen saturation level, usually presented as a percentage, and a heart rate. Oxygen saturation values ​​are between 95% and 100% for most healthy people. Besides skin pigments, poor circulation, cold skin, and nail polish can interfere with the accuracy of readings.

In the early stages of the pandemic, health officials advised people to buy pulse oximeters over the counter monitor their oxygen levels without having to go to a health facility.

Following a previous study which was published in the New England Journal of Medicine in December 2020, the FDA issued a security communication in February 2021 warning against relying solely on pulse oximetry to determine oxygen levels.

On June 22, the FDA announced plans to hold a public meeting of the Medical Devices Advisory Committee to address concerns about the accuracy of pulse oximeters for darker-skinned patients.

Dr. Eddie Richardson Jr., owner of Lake Oconee Primary and Urgent Care Center and a hospitalist at Putnam General Hospital, both in Eatonton, is confident he used the sometimes necessary follow-ups to pulse oximetry with more of 250 coronavirus patients who he has seen throughout the pandemic.

“In my clinical practice, I’d say I’ve probably noticed a few discrepancies. But, while I was thinking about it, since O² (oxygen) was not our only indicator, we looked at CT scans, chest x-rays and tests and made clinical decisions based on that,” did he declare.

However, Richardson keeps in mind the “domino effect” that a disparity like that found in pulse oximetry can have in healthcare.

“If you don’t look for him, you won’t find him. If you don’t know these biases exist, you won’t be sensitive to them,” Richardson explained. “It only further underscores the racial and ethnic disparities in our healthcare system and the bias in how we treat patients in general.”

An alternative to pulse oximeters is an arterial blood gas (ABG) test, considered the “gold standard” for determining oxygen levels. But they require a painful blood draw and additional equipment, treatment, time and money.

Because of their availability and affordability, pulse oximeters “are fantastic for giving us a really good idea of ​​our patients’ oxygen saturation levels,” said Dr. Cecil Bennett, family physician at Newnan Family Medicine. Associates and Adjunct Professor at Morehouse. Medicine School. “This really is a relevant study that shows that even if done right, pulse oximeter calibration may not be best for people of color.”

Doctors say the implications of incorrect pulse oximeter readings in Georgia are wide, especially among black people.

ExploreStudy links racism and segregation to increased COVID deaths

“In areas of the country where there are high concentrations of minorities, these things are important. African Americans have a higher likelihood of being underdiagnosed across the board,” Bennett said. “It’s just another situation we find ourselves in where we depend on a device to give us accurate readings and we find out years later after COVID started that the device isn’t as accurate as we would do it like African Americans.

When Dr. Bonzo Reddick, director of the Department of Community Medicine at Mercer University School of Medicine, spoke to The Atlanta Journal-Constitution, he thought of the black and brown coronavirus patients who have been sent home but are returned to the hospital in worse condition.

“I had patients who were sent home because they were thought to be well enough to be cared for at home, and they ended up being readmitted to hospital later,” Reddick recalls. “It made me wonder if their oxygen levels were really normal the first time they were assessed or not.”

For other doctors, the focus on race in the report shows a missed opportunity within an important study.

Dr. Camara Phyllis Jones is a family physician, epidemiologist, and adjunct professor at Emory University’s Rollins School of Public Health and Morehouse School of Medicine. She has devoted much of her work to combating racism in medicine and in general.

Jones noted that the original study was based on the patients’ self-proclaimed race rather than their actual skin tones — a more variable measure that would apply to more people.

“They (the researchers) didn’t have skin tone, which would have been the perfect metric to really understand the flaws in pulse oximetry and how we use it now,” Jones observed. “They identified a significant problem and all they had was a self-identified ‘race’ as a proxy for a group of skin tones…. It’s about light absorption, so it has to do with skin tone.

She said the study’s focus on race fails to capture the biology surrounding the oximetry problem. “We have to let go of our notion of ‘race’ as something biological,” she said.

Jones, like many other doctors, believes that something needs to be done on a fundamental level regarding the problem in pulse oximeters.

“Structural racism often manifests itself in a lack of action in the face of need,” Jones noted. “Now we better see the pulse oximeter makers try to fix this problem they’ve known about since the New England Journal article in 2020.”


How to use a pulse oximeter

• When placing the oximeter on your finger, make sure your hand is warm, relaxed, and held below heart level. Remove any nail polish on that finger.

• Sit still and do not move the part of your body where the pulse oximeter is located.

• Wait a few seconds until the reading stops changing and shows a fixed number. Oxygen saturation values ​​are between 95% and 100% for most healthy individuals, but can sometimes be lower in people with lung problems.

• Check if the oxygen level is lower than previous measurements or decreasing over time. Changes or trends in measurements may be more significant than a single measurement.

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