If you have dark skin, you will run out of pulse oximeters.

Over the last two years, pulse oximeters have become an important tool for tracking the health of COVID-19 patients.

A small device is clipped to your finger to measure the amount of oxygen in the patient’s blood. However, ever-increasing evidence shows that the device can be inaccurate when measuring oxygen levels in people with dark skin.

A study Published on Monday only adds to this concern.

Researchers analyzing pre-pandemic health data also found that these measurements resulted in color patients receiving less oxygenation than white patients.

“We were fooled by the pulse oximeter,” said the lead author of the study. Dr. Leo Anthony SeriMIT Institute for Computational Physiology, Clinical Research Director and Principal Investigator.

“We were given the false impression that the patients were okay, and what we showed in this study was that they were giving them less oxygen than they needed.” He says.

These cool discoveries bring the urgency to educate patients and healthcare professionals about the shortcomings of pulse oximeters, and to design new models that work reliably regardless of someone’s skin color. ..

Doctor fights to take care of his son

It was last September that Dr. Sandra Ruby Gordon saw how a flaw in this device could affect his family.

Looby-Gordon, a doctor at the Boston Medical Center, finds himself over the phone with a triage nurse in a Florida hospital and claims that he needs to admit his son, who was very ill with COVID-19, to the hospital. did.

“Well, yeah, he looks short of breath,” Ruby Gordon remembers the nurse saying, “But his oxygen levels are good.”

The nurse was based on reading this from a pulse oximeter clipped to his finger, but this rating did not feel right to Looby-Gordon.

She hung up with the nurse and talked to another doctor at the medical center.One of them reminded her Articles for 2020 In New England Journal of Medicine The pulse oximeter display tends to be inaccurate for people with dark skin.

“In addition, my son-which sounds strange-is a very dark, very dark complexion,” says Looby-Gordon.

Sure enough, when her son later underwent a more invasive test to measure blood oxygen, it showed that his oxygen levels were actually dangerously low.

He was admitted to the hospital, treated, and eventually recovered from COVID-19. However, Looby-Gordon says that most patients in their situation are unaware of the shortcomings of pulse oximeters.

Even herself, a black doctor, wasn’t fully aware of how misleading the device could be, she says.

Investigation reveals device shortcomings

If anything, the pandemic highlights this long-standing problem with pulse oximeters.

research Release last month According to scientists at John’s Hopkins University, inaccurate pulse oximeter results could not identify black and hispanic patients who needed COVID-19 treatment such as steroid dexamethasone or antiviral remdecibir. Is shown.

COVID-19 Colored race through the crisis Experienced The rate of hospitalization and death from COVID-19 is higher than that of Caucasians. MIT’s Celi says it’s impossible to know how much the pulse oximeter contributed to the disproportionate effect of COVID-19 on people of color, but he believes it played a role. increase.

And this issue points to a bigger issue regarding how medical devices are researched and approved. “The method of evaluating medical products is based primarily on trials in Caucasians,” says Celi.

FDA guidance In order to approve the pulse oximeter, clinical trials should include at least two darkly pigmented individuals, or 15% of the subject pool, whichever is greater. However, some doctors and scientists say that is not enough, especially because the range of skin tones is so wide.

Several manufacturers of pulse oximeters — Edwards Life Sciences, fields When Nonyne — Proprietary version of the device claims to actually provide accurate results that take skin color into account.

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In 2021 Editorial In response to the New England Journal of Medicine According to the article, Masimo Corp.’s CEO explains how many discrepancies between the results of that study and their own internal studies, such as sickle cell disease and cardiovascular problems that affect blacks disproportionately. I suggested that hypothesis.

Scientists look for a solution

Scientists and engineers are increasingly working on new technologies that could revolutionize pulse oximeters, so they work the same for dark-skinned people.

Rutendo Jakachira, a PhD student at the Optical Laboratory at Brown University, explains how the pulse oximeter works.

“When you put your finger in this groove, the LED on the top shines on your finger,” says Jakachira. The device can then calculate the patient’s oxygenation by calculating the amount of light absorbed by hemoglobin in the blood.

“That’s the key to the problem seen in people with dark skin,” he says. Kimani Tusan, Professor of Electrical and Computer Engineering, Biomedical Engineering, and Mechanical Engineering at Brown University. “We assume that the only absorber of light energy is hemoglobin.”

But in reality, skin pigmentation also absorbs light, he says. Also, for people with dark skin, readings from a pulse oximeter can overestimate the amount of oxygen in the blood.

Toussaint stands next to a table full of technology that wants to solve the problem.

“I don’t call this a device yet,” he says.

Unlike current pulse oximeters, devices that are not yet sufficient use polarization that is not absorbed by skin pigmentation. If it works, Toussaint says it will partner with the manufacturer to reduce everything to a device that can be sold.

At Tufts University Valencia Comson We are working on addressing this issue using a different approach.

Her device uses the same type of light as the pulse oximeter currently available, but includes a technique that can measure a person’s skin tone (the darker the skin, the higher the level of melanin. Become).

“In the presence of higher levels of melanin, we can send more light, so melanin is not a entanglement factor that obscures our results,” said an associate professor of electrical and computer engineering. One Coombon says.

Black, Koomson, talks about the pulse oximeter, and now the ongoing efforts to redesign it point to the need for greater diversity in engineering and medicine.

“We are shaped by our environment, who we are, and our identity,” she says. “It tells us what kind of research is being done. It is the people doing the research who decide what kind of research is going on.”

Coombson and other scientists are also urging the Food and Drug Administration to take steps to address the problem.

“If the patient is at home and not closely monitored in the hospital, we need to make sure that these numbers are as accurate as possible so that we can make a clinical assessment,” the two said. The Emergency Medicine Society that I sent letter To the FDA about the problem of pulse oximeters.

Distributors are starting to respond.

Last winter, the FDA warning Skin pigmentation and other factors can affect pulse oximeter results. Now it is funding the research in question, Gather expert advisors Later this year, we’ll discuss how to make sure your device is accurate for everyone.

Despite years of publication on this issue, Koomson says it’s not as well known as it should be.

She says that racists, the national heritage of pseudo-scientific research, are wary of scientists exploring physical differences between people of different races.

“People are afraid to talk about physical differences because they don’t want to look discriminatory,” says Koomson. “But I think we need to discuss aspects that affect people’s health and the care they receive.”

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