Pulse oximeters are designed to provide valuable medical information about patients by measuring oxygen saturation in red blood cells, yet, inaccurate readings from these devices likely cost lives during the COVID-19 crisis. This problem isn't unique to the pandemic, however. New research in JAMA Pediatrics evaluating data from 2016 to 2021 showed "that pulse oximetry overestimated arterial oxygen saturation in children of Black or African American race."
It's time to reevaluate how we incorporate cultural awareness into medical practice so we can safely conduct medical monitoring of all our patients.
Oftentimes it's a good thing when patients take charge of their own health using remote devices, as they did when the COVID-19 pandemic started -- but only if a knowledgeable professional is at the other end to monitor, evaluate, and interpret the device's readings. That professional needs to know the full context of the patient's health -- from their baseline oxygen levels to their skin tone -- so they know when they might be seeing questionable oxygen saturation readings and need to bring the patient in for further evaluation.
All pulse oximeters are not created equal, nor are they all approved by FDA. There's also a long list of factors that interfere with the readings, something that professionals and non-professionals may not know.
Clipped to fingers, toes, or earlobes, pulse oximeters need light to pass through the patient's skin to measure whether a patient's oxygen level is high enough to keep cells "healthy," typically above 89%. It's quick and non-invasive.
Our patients may not know that the readings they see at home are only "reasonably" accurate, or that light from a pulse oximeter doesn't pass as well through dark (melanin-rich) skin, leading to inaccurately high oxygen saturation readings. Patients also may not be aware that most pulse oximeters give a reading 2% over or 2% under what their saturation would be if obtained by a more invasive, but more accurate, arterial blood gas.
The device has other limits too: thick skin, cold fingers and toes, nail polish, poor lighting, and a patient's smoking status can all interfere. Patients using pulse oximeters without this information -- and without medical guidance -- may not seek lifesaving care when their oxygen levels are, in reality, dangerously low.
Unfortunately, these problems can also be a blind spot for practitioners, as they are overlooked in medical training and practice. We've already seen the impact.
One study says the biases in pulse oximeters "were associated with greater occult hypoxemia [extreme low oxygen saturation] in Asian, Black, and non-Black Hispanic patients with COVID-19, which was associated with significantly delayed or unrecognized eligibility for COVID-19 therapies among Black and Hispanic patients." This is another massive, unacceptable hit to some of the communities that experienced the pandemic's highest death rates.
Tools to reduce colorism in the use of medical devices may help medical professionals determine when to consider skin tone in pulse oximeter readings and treatment. For example, the Monk Skin Tone Scale offers a palette of 10 skin tones (up from the previous six) to cover a wide range of communities and backgrounds. By itself, however, this approach doesn't solve the biases in pulse oximeters. A project called Open Oximetry has developed a collaborative effort to improve access to accurate pulse oximeters worldwide by sharing data and developing new standards and technologies for oximeter validation. The FDA has acknowledged the limits of the devices, too, and convened its outside experts to review data on them last fall.
Such initiatives come too late for those whose medical care was compromised -- or not administered at all -- because of inaccurate readings. It does no good for those who can't afford the best quality devices or the extra costs for continuous monitoring. It also doesn't help those who don't have information about the device's limits or know when to consult a medical professional.
We have a chance to change that moving forward by ensuring health professionals have the medical and cultural knowledge to adjust pulse oximetry readings when necessary, especially when patients are using the devices at home. Additionally, because people may buy pulse oximeters outside of the recommendation or care of a health professional, it's essential that pulse oximeter manufacturers prominently publicize the FDA's warning: "multiple factors can affect the accuracy of a pulse oximeter reading, such as poor circulation, skin pigmentation, skin thickness, skin temperature, current tobacco use, and use of fingernail polish."
Simply having a pulse oximeter in the home is not sufficient. It is not the same as medical care.
However, if we add wider patient understanding and professional knowledge to continuous professional monitoring, we have a chance to gather information and intervene in a way that can save lives.
Anthony M. Szema, MD, is director of the International Center of Excellence in Deployment Health and Medical Geosciences, and clinical professor of medicine in the Division of Pulmonary and Critical Care in the Division of Allergy/Immunology at Northwell Health in New York.