The device used to measure blood oxygen levels can give inaccurate readings for Black patients, making levels appear better than they actually are.

As hospitals struggle to prioritize patients during the pandemic, one of the very medical tools they rely on to determine care gives incorrect oxygen-level readings in Black patients.

COVID-19 often causes a dangerous drop in blood oxygen levels in patients. Black Americans, who have also been dying from COVID at a higher rate than white people, can now add healthcare technology to the list of things that can contribute to adverse outcomes and medical racism.

“Unfortunately, discrimination exists in systems meant to protect well-being or health,” notes the Centers for Disease Control (CDC). “Discrimination, which includes racism, can lead to chronic and toxic stress and shapes social and economic factors that put some people from racial and ethnic minority groups at increased risk for COVID-19.”

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A recent study in The New England Journal of Medicine revealed that healthcare technology, specifically pulse oximeters used to determine oxygen levels, is not immune from contributing to racial health disparities.

The pulse oximeter is a device placed on the fingertip to measure the amount of oxygen in the blood. Because one of the most telling symptoms of COVID-19 is shortness of breath, oxygen level readings are a vital sign in hospitals and healthcare settings. 

Dr. Michael Sjoding, lead researcher and pulmonologist, noticed inconsistencies in the device’s oxygen readings compared to when blood is drawn directly from an artery among darker-skinned patients. Sjoding, along with colleagues, studied this phenomenon and made a startling discovery. Pulse oximeters gave darker-skinned patients readings that were much higher than the actual oxygen levels determined by further testing. “We found this happened much more often in patients who were Black. Basically, about three times more often,” he told NPR

The discriminatory design of the device is to blame. The pulse oximeter reads oxygen levels by passing light through the skin to see blood. They were initially developed, calibrated, and tested on white people. The failure of these devices to properly read Black patients’ oxygen levels has been a known issue for more than 20 years, but the need to address it has become crucial recently.

Nurses, doctors, and other healthcare workers often use oxygen readings to determine the next clinical steps. Across the US, hospitals are overwhelmed with a record number of COVID patients. Without enough beds, space, and ventilators, hospital staff are forced to make tough decisions and prioritize who gets care—and ultimately, who lives or dies. 

Despite the reading, Black patients can make doctors aware of their difficulty breathing, but studies show that Black people aren’t taken seriously when they share their pain and discomfort with doctors. 

Patients at higher risk for COVID symptoms can also use a pulse oximeter at home to monitor their breathing. It can be purchased over the counter without a prescription, with many patients relying on its results to determine when to seek emergency medical care.