COVID: Is the pulse oximeter inaccurate for black and Hispanic patients?

Inaccurate pulse oximetry measurements in black and Hispanic COVID-19 patients in the United States are associated with significant delays in treatment or ineligibility for specific treatments, Johns Hopkins Medical and Baylor College of Medicine. A new study by.

Although it has been a concern for decades, awareness of overestimation of oxygen levels in patients with dark skin tones by inaccurate pulse oximeter measurements increased during the COVID-19 pandemic. rice field. New research, Announced at JAMA Internal Medicine on TuesdayMore and more studies are investigating racial and ethnic prejudices and discrepancies, and their impact on treated patients.

According to co-lead author Dr. Tianshi David Wu, among the more surprising findings was the fact that about 25% of people should have received more aggressive treatment, but not, and the majority of those individuals. There was the fact that was black or Hispanic. In addition, pulse oximeters did not identify oximetry values ​​below 94% for most people, more than half of whom were black.

In a telephone interview with CTVNews.ca on Monday, Wu, an assistant professor of lung and critical care at Baylor University, said, “Health and racial disparities and the social determinants of COVID-19 results are well explained. I have. “

“People who identify themselves as racial or ethnic minorities are more likely to die from COVID-19, and we speculate that this type of technical prejudice may essentially contribute to some aspect of the difference. doing.”

Wu and his colleagues want to investigate this issue in the context of COVID-19 because of its relevance to the treatment of COVID-19 and how widely used pulse oximeters are around the world. Was there.

“Unlike other diseases, the severity and COVID classification depends on pulse oximetry or oxygen saturation,” Wu said.

“Therefore, the treatment decisions we make are overly dependent on the oxygen saturation value … and we cannot pass the hospitalization without measuring the oxygen saturation with a pulse oximeter.”

Wu has shown that the National Institutes of Health and other international guidelines are all eligible based on the diagnosis of severe COVID-19 or low pulse oximetry levels, along with prescribing information for drugs such as remdesivir and dexamethasone. Said.

A retrospective cohort study that collected data from five hospitals within the John’s Hopkins Health System found that arterial oxygen saturation in Asian, black, and Hispanic individuals was continuously overestimated.

“Comparing pulse oximetry measurements to arterial oxygen saturation, at least one unidentified value compared to about one-third of patients in each race or minority group and less than one-fifth of Caucasian patients. There was a hypoxic episode of “,” the author wrote in a study. Hypoxia is when the tissue does not have enough oxygen.

“In addition, there are statistics on systematic failures to identify black and Hispanic patients who may be eligible for COVID-19 treatment and recognition of recommended thresholds for starting treatment for black patients compared to white patients. I found that it was significantly delayed. “

How does a pulse oximeter work and why can it be inaccurate?

Pulse oximetry is a non-invasive method of monitoring the amount of oxygen in a person’s blood and can quickly detect changes in these oxygen levels. This has become a particularly useful tool in determining patient care during a pandemic, with recommendations for hospitalization and approval of specific drugs based on specific thresholds measured by an oximeter.

Other body parts, such as ear lobes, may also be used, but the device usually clips to the finger. First developed in Japan in the 1970s, this device typically works by sending LED light to the skin at two different wavelengths and analyzing the amount of light absorbed at those wavelengths and passed to the other side. increase. Melanin, a pigment found in dark skin, tends to absorb more light through the skin.

By the late 1980s, this device had become more commonly used in certain medical settings, but as early as 1989, when obtaining appropriate measurements in dark-skinned patients. Researchers have reported that the problem has increased significantly. According to a 1990 study, pulse oximetry measurements appear to be nearly 2.5 times less accurate in black patients, and calibration data comes primarily from white patients, making them reliable. Researchers speculate that it is low.

A letter from a team of physicians at the University of Michigan School of Medicine, published in the New England Journal of Medicine in December 2020, spotlights this known problem and how differences in pulse oximeter measurements increase the risk for black patients. I did. Specifically, their study found that in two large cohorts, black patients had three times as much latent hypoxemia as white patients.

Latent hypoxemia is when arterial oxygen saturation is less than 88%, even though pulse oximetry readings are 92-96%.

In an article published in the annual report of intensive care in January this year, Dr. The researchers behind the 1990 study, Martin Tobin and Amal Jubran, said:

“Inaccuracies in pulse oximetry in black patients are another example of how medical information generated in Caucasians (and for Caucasians) contributes to lower clinical outcomes in color patients. “They added.

JAMA survey results

The authors of the Johns Hopkins / Baylor study found that overestimation of oxygen levels may be associated with early reduction of treatment or premature discharge of inpatients, or with delay or withholding of treatment. He said it could, or else it could help shorten the duration of the illness. It slows its progress or reduces the chance of death.

Of the 7,126 patients with COVID-19 analyzed in the JAMA study, latent hypoxemia occurred in 30.2% of Asians, 28.5% of blacks, and 29.8% of non-Black Hispanics. Among Caucasian patients, it was 17.2 percent.

Researchers have found that the risk of black patients is 29% lower and that of non-black Hispanic patients is 23% lower in the risk of therapeutic eligibility recognition. A total of 451 patients, or 23.7%, were not admitted to treatment. 54.8 percent of those patients were black.

Of the remaining 1,452 patients (76.3%) who were ultimately qualified, black patients had a median delay of one hour longer than white patients.

The use of pulse oximeters has also moved beyond hospital settings, especially during pandemics, and is becoming more affordable and more used at home. Wu and his colleagues expressed concern about how it affects the speed at which patients seek professional care and how they assess their illness.

“Black individuals who test positive for COVID-19 in an outpatient setting are not advised or delayed to seek care based on false reassurance from regular pulse oximetry measurements. May decide, “the author wrote in the paper.

“Such a scenario was reflected in the overestimation of black patients who were not recognized for their eligibility for treatment with remdesivir and dexamethasone.” They said that this problem was associated with other problems such as pneumonia and acute respiratory distress syndrome. He added that it may also be involved in the treatment of respiratory disorders and the determination of triage.

Some of the study’s limitations included the fact that the race and ethnicity used in the study were self-reported, so researchers measured differences in skin tone within each race or ethnic group. Or couldn’t explain. Researchers also said the results may not be generalized to healthy or less severe people. They also say that the use of oxygen saturation thresholds and drug eligibility is an incomplete estimate of the actual delay in treatment, as other factors such as drug availability are also involved. Said.

“Pulse oximetry has become a fundamental tool in diagnostic, triage, and management decisions in the acute care environment, but the lack of device accuracy in certain populations has been recognized and emphasized for decades. It has been, but has not been properly investigated or addressed. In the 2020 Safety Communication by the US Food and Drug Administration, “the researchers write.

In the short term, it’s important to spread the word to raise awareness about this issue, and Wu says the threshold for measuring oxygen saturation should be more liberal.

But in the long run, he and his colleagues believe that the solution needs to change technology to accommodate different skin tones. “Technology fixes … are certainly feasible. It hasn’t been done yet,” he said.

“With this prejudice against such an important tool, it is a difficult position for frontline physicians and clinicians to face.”