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  • A recent study found that a key tool for reading blood oxygen can give inaccurate readings for Black and Hispanic patients.
  • Pulse oximeters are placed on a person’s finger and can help monitor how oxygenated their blood is.
  • These pulse oximeter readings can be key for monitoring people with COVID-19.

New research has found that pulse oximetry readings — a tool used to measure blood oxygen saturation levels and guide treatment options for COVID-19 — have been less accurate in Black, Asian and Hispanic patients.

The study, recently published in JAMA Internal Medicine, also found that Black and Hispanic patients were more likely to experience delayed or unrecognized eligibility for COVID-19 treatments.

The findings add to previous research suggesting that inaccurate pulse oximeter readings are more common among Black and Hispanic people, which can lead to life-threatening delays in treatment.

Evidence consistently shows that Black and Hispanic people are more likely to be hospitalized and die from COVID-19. Last year, the Food and Drug Administration (FDA) issued a warning that pulse oximeters may be less accurate in people with dark skin pigmentation.

“This and other studies show that pulse oximeter readings in persons with more pigmented skin can be lower than the readings of those with lighter skin. So, both providers and persons using pulse oximeter at home and for treatment interventions need to be aware of this difference when using this data,” says Dr. Laura Vaughan, an internal medicine physician and clinical assistant professor of primary care medicine and population health at Stanford Medicine.

The researchers evaluated the health data of 1,216 patients with oxygen saturation levels measured by two different tests — pulse oximetry and arterial blood gas — and found that oxygen levels were often overestimated among Asian, Black, and Hispanic patients.

Black patients’ oxygen saturation levels were overestimated by 1.2 percent compared to white patients. Hispanic patients’ levels were overestimated by 1.1 percent and Asian patients by 1.7 percent.

Black and Hispanic patients were also 29 percent and 23 percent less likely to be recognized for treatment eligibility compared to white patients.

The researchers also analyzed the data of over 6,500 patients with COVID-19 and, based on their findings, predicted that over 1,900 patients’ oxygen saturation levels were likely overestimated, leading to delays and failures in life-saving treatments.

“This study’s results suggest that for critical treatment decisions that rely on arterial oxygen saturation, use of pulse oximetry may be inadequate and produce opportunities for undertreatment and overtreatment irrespective of the patient’s race or ethnicity,” the researchers stated in the study.

Past research has identified racial biases in pulse oximeter readings.

A report published last year in JAMA Network Open found that inaccuracies in pulse oximeter readings increase the risk of death in Black patients.

Another study, published in Anesthesia & Analgesia, similarly found that pulse oximetry overestimates oxygen levels in people with darker skin pigmentation compared to those with lighter skin pigmentation.

Pulse oximeters — a device placed on a patient’s finger — are used to measure the amount of oxygen in red blood cells in emergency situations.

“Oxygen saturation gives information about the amount of oxygen carried in the blood. The pulse oximeter can estimate the amount of oxygen in the blood without having to draw a blood sample,” says Dr. Geraldine Finlay, a pulmonologist and senior deputy editor for Pulmonary and Critical Care Medicine at UpToDate at Wolters Kluwer, Health.

Healthy people’s oxygen saturation typically falls between 95 to 100 percent.

With COVID, oxygen levels are often the first sign of a downturn, according to Vaughan.

Many patients with COVID-19 experience low oxygen levels, which is a life-threatening condition that can cause difficulty breathing, chest pain, confusion, and a fast pulse.

Some patients with low oxygen levels, or hypoxemia, may remain asymptomatic, which can lead to rapid deterioration, according to Finlay.

COVID-19 patients with low oxygen levels should start oxygen therapy to boost their oxygen saturation to at least 90 percent, according to the Centers for Disease Control and Prevention.

Pulse oximetry has also been used to inform whether patients should begin more aggressive therapies, like the antiviral remdesivir or the corticosteroid dexamethasone, which were routinely given to patients with low oxygen levels during the pandemic.

“Some of the current hospital treatments guidelines use oxygen saturation to determine offering these treatments. Also, a delay in recognizing this decline can lead to delays in these treatments,” says Vaughan.

According to the FDA, multiple factors can impact the accuracy of pulse oximeter readings, including poor circulation, skin pigmentation, skin thickness, skin temperature, tobacco use, and fingernail polish.

Pulse oximeter readings only estimate a patient’s blood oxygen saturation. A pulse oximeter saturation of 90 percent may reflect an oxygen saturation of 86 to 94 percent, according to the FDA.

Healthcare providers should make diagnoses and treatment decisions based on multiple pulse oximeter readings to get a more accurate look at a patient’s oxygen saturation levels.

Vaughan says that healthcare providers need to be aware of the discrepancies in people with darker skin and factor this into their decisions to seek further evaluation and treatment.

“Hospitals should facilitate open discussion to help foster awareness among physicians and healthcare workers about the overreliance on oximetry for clinical decision-making. Care teams need to be armed with knowledge and awareness of how healthcare has left gaps and health disparities for Black patients,” says Finlay.

New research has found that pulse oximetry readings — a tool used to measure blood oxygen saturation levels and guide treatment options for COVID-19 — have been less accurate in Black, Asian and Hispanic patients. Due to these discrepancies, non-white patients are more likely to experience delays in life-saving treatments. Physicians hope healthcare providers factor in these findings when treating Black, Hispanic and Asian people with COVID.