SANTA CRUZ – For years a growing chorus of research suggested that pulse oximeters, a clip-on blood oxygen measurement device made ubiquitous by the COVID-19 pandemic, may give inaccurate readings in darker-skinned patients.
However, experts say that until recently, little was known about the specific adverse clinical effects this potential bias could have.
Analyzing data from the COVID-19 pandemic, a study by Sutter Health found that the inability of a pulse oximeter to accurately read blood oxygen levels in black patients may have led to 4.5 hours of treatment delays, according to the supplier’s declaration.
Oakland-based Roots Community Health Center and UC San Francisco collaborated on the research work.
Study officials recently told the Sentinel that because COVID-19 treatment guidelines put a non-invasive fingertip device at the forefront of clinical threshold detection, its limitations may have had real ramifications.
One of the paper’s lead authors is Sylvia Sudat, an accomplished scientist and biostatistician from Sutter.
Sudat was raised in Santa Cruz County, graduated from Harbor High School, and spent most of her childhood in a lab in Scotts Valley, where her mother worked as a clinical lab scientist.
“I felt close to healthcare, but I also saw how difficult it can be to navigate, even with a family member working in healthcare,” he told the Sudat Sentinel, later adding that “the best care is fair care.”
Sudat, a senior biostatistician and scientist at the Center for Health Systems Research, and a principal member of the Sutter Health Institute for Advancing Health Equity and the Data Science team, said that while the device systematically overestimates blood oxygenation by 1% more in non-Black Hispanic patients, this seemingly small difference has profound implications.
“People said to me, ‘Well, it’s no big deal, why are you so excited about it?’ Sudat said. “When we talk about health care and human survival, small systematic differences matter and we need to take them seriously.”
In addition to delays in treatment, overestimation in black patients, according to Sutter Editionwas also associated with:
• Increased duration and less likelihood of receiving dexamethasone, a drug used to treat COVID-19.
• Less likely to be admitted to hospital.
• Less likely to receive additional oxygen treatment.
Sudat explained that the device detects oxygen levels by passing light through a finger. However, melanin – the natural pigmentation – absorbs some of this light, which systematically shifts the reading. The more melanin, the darker the skin tone.
“Because it’s a universal device, it doesn’t mean the same thing,” said Sudat. “It’s not just that it’s more variable or there’s just more inaccuracy, it (the measurement) has actually moved up, so basically the translation between what you see on the pulse oximeter and what’s actually going on in your blood, is different.”
Kristen Azar, the study’s senior author, said black patients were more likely to have arterial blood gases performed, which is the gold standard for measuring blood oxygen levels but is invasive and often painful.
She said clinicians may order the test as a confirmatory tool, especially if the symptoms a patient is showing are significantly different from the pulse oximeter reading.
“It was harder for clinicians to adequately treat those patients who were suffering from COVID-19, resulting in measurable treatment delays,” said Azar, “which contributes to structural racism in healthcare, regardless of the doctor’s intentions.”
Sutter’s study focused on patients outside of Santa Cruz and only those who had COVID-19 symptoms in the emergency department.
Still, the device is widely used in many medical settings, and Azar said the study has important implications for unconscious biases in healthcare technology and the industry as a whole.
“Awareness, awareness, awareness,” Azar said when asked about the practical applications of the study. “If you’re going in and this device might not mean the same to you as it does to others, just make sure you’re defending yourself. The same goes for doctors.”
As you can see, awareness is growing.
Last month, the Food and Drug Administration convened a team of experts to discuss “continuing issues” with your device.
According Associated Press reportIndustry experts hope the meeting will result in updated agency testing guidelines that include testing criteria and specific requirements for inclusion of people with different skin pigmentation.
The AP also reported that some companies selling pulse oximeters disagreed with the view that the devices are less accurate for patients of color. One CEO of medical device company Masimo said an internal review found no evidence of significant differences in accuracy among black patients.
Still, Azar and Sudat say the evidence is mounting, and this may just be “the tip of the iceberg.”
“We can’t sweep these differences we found under the rug just because we decided they weren’t important,” Sudat said. “We need to take them seriously and make sure that the devices we have enable our clinicians to properly care for patients, regardless of their skin color.”
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