OPINION: Are Pulse Oximeters Ultimately Harmful To Black Medical Patients?
As I walked through the intensive care unit at Chicago’s Rush University Medical Center during the initial surge of the COVID pandemic as a pulmonary and critical care physician, I kept asking myself the same question: Why are the Black patients dying?
Our hospital was full of COVID-19 patients, but why were the sickest patients who were dying from severe disease Black? My observations were not unique to our hospital, the CDC reports show that compared to White people, Black people had 2.3 times the hospitalization rate and 1.7 times the death rate. The CDC specifies that “race and ethnicity are risk markers for other underlying conditions that affect health, including socioeconomic status, access to health care, and exposure to the virus related to occupation e.g., frontline, essential and critical infrastructure workers.” Hence, the structural racism that is embedded in our healthcare system results in worse outcomes for minority populations.
But that wasn’t a complete answer to the question. Could it be that the inaccurate measurement of oxygen levels in Black patients is a culprit?
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Most complications caused by COVID-19 leading to hospitalization were related to a patient’s lungs which would ultimately cause the patient to require oxygen in various forms of support, including the ventilator in the most severe cases. A patient’s oxygen level determines if they would be discharged from the emergency room, admitted to the hospital, or transferred to the intensive care unit. Later when treatment options became available, their oxygen level would determine if the patient were a candidate for specific, life-saving therapies. As a result, accurate oxygen information is crucial.
Pulse oximeters are routinely used to estimate oxygen levels in a patient’s blood by clipping onto a body part, most commonly the patient’s finger. However, recent studies have revealed serious limitations to the pulse oximeter, including inaccuracy in patients with darker skin pigmentation.
A letter published in the New England Journal of Medicine concluded that patients that were identified as Black were three times more likely to have inaccurate oxygen levels measured by pulse oximeters compared to White patients. Consequently, a Black patient with low oxygen levels may not get the care needed because the oximeter reading is normal. Also, a recent study published by the American Medical Association showed that Black and Hispanic patients were more likely to experience delay receiving therapy for COVID-19.
The U.S. Food and Drug Administration has recognized this limitation and issued a safety alert to address the ongoing concern of the inaccuracy in those with darker skin pigmentation. While there are new devices under development, like one at Brown University, to assess the inaccuracy in people with darker skin, until such devices are available for widespread use, doctors and patients must be aware of this issue.
Discrepancies with the pulse oximeter is not the first-time medical devices have provided inaccurate information for people of color. For years the spirometer, a device used to measure lung function, has been based on stereotypes. Samuel Cartwright, a plantation physician who enslaved Black people created his own spirometer and arbitrarily noted a 20 percent racial difference in lung function – denoting that black people had lower lung function that white people without scientific basis.
Since that time, White has been the standard of normal for lung function testing. Race correction has been used through a correction factor or standards specific to a population that have been accepted by professional societies. Because race is entered by a respiratory therapist when obtaining testing, some patients are misclassified. Stated race/ethnicity is a subjective assessment and is not a reliable or valid measure. Additionally, when race correction is used, abnormalities of lung function are missed in black patients. Race correction has been used when interpreting pulmonary function testing since the creation of the device.
The use of medical devices that harm Black patients through inaccuracy deserves the urgent attention of the medical profession. Acknowledging the limitations of devices such as pulse oximeters in darker pigmented individuals and understanding the racism behind the interpretation of spirometry are crucial.
While developing new devices that account for differences in skin color and removing race correction in medical testing are steps in the right direction, we have so much work to do to address the damage done from hundreds of years of systemic racism that has been perpetuated in medicine.
Dr. Abhaya Trivedi is an Assistant Professor of Medicine in the Division of Pulmonary and Critical Care at Rush University Medical Center and a Public Voices Fellow with the OpEd Project. She serves as the Associate Program Director for the Pulmonary/Critical Care Training Program.