The Pulse Ox Paradox

By Brooke Wheeler 

You may have read recently about the Masimo vs. Apple lawsuit in the news – a $1.2 billion dollar company suing a $400 billion company over a bit of technology called pulse oximetry. Pulse oximetry tells you how much oxygen is in your blood. It’s something your Apple Watch can do (the crux of the intellectual property lawsuit) and also the job of a small plastic device that can be clipped on a finger or toe in the hospital or bought to monitor your or a loved one’s blood oxygen at home. 

Pulse oximeters are small devices that are a multi-billion-dollar business – expected to keep growing 6% to 9% each year. Anyone can buy one in a drugstore or online; they range from $10 to around $60. But there’s a big problem: It turns out they often don’t work right for people of color. 

Vital signs of trouble 

Pulse oximeters are relied on as an essential healthcare tool. They’re used in hospitals and at home for millions of people to see if their bodies are getting enough oxygen – a necessity if you’re just out of surgery, have asthma or COPD, or an illness like Covid or pneumonia. They’re used on high-risk newborns, cancer patients, and people with heart disease – and the latter is still the number-one cause of death in the United States. 

But their skyrocketing rate of use during the height of Covid highlighted how—while this small device is crucial for health—it can often fail people with darker skin tones, putting them at risk of their low oxygen levels going undiagnosed. It’s because of how pulse oximeters measure blood oxygen: by shining light through your skin. 

A pulse oximeter – often shortened to pulse ox in clinical settings – sends both red light and infrared light through your finger or toe to a sensor on the other side of your finger or toe. Oxygenated proteins in your bloodstream absorb a certain amount of this light. The sensor measures how much light has been absorbed as it passes through your blood vessels and tissues. It's then calculated as a percentage to show your oxygen saturation, or O2 sat. 

But anything that reduces the waves of light can affect the accuracy of the reading. And studies have found that pigment in skin can change how much light gets through to the sensor – and result in a false reading that shows results closer to normal when a person may actually have low oxygen levels (called hypoxia). This is a dangerous inequity that the FDA has been grappling with since 2021, when they issued a safety warning about the limitations of pulse oximeters to patients and healthcare providers. 

Our DEIA commitment 

Diversity, Equity, Inclusion, and Accessibility are crucial aspects of the way we craft our content at WebMD Ignite. We're continuously analyzing the best ways to make our content respectful and inclusive to all people. Part of that means recognizing barriers to equitable medical care. The pulse oximeter problem is a barrier of equity for patients of color. 

Our editorial and clinical teams are producing new content to address the pulse oximeter problem across our products so we can help patients and their caregivers with information and guidance. Meanwhile, we continue to monitor the FDA’s guidelines and see how the pulse oximeter inequity problem is addressed. 

Our mission in action

Our mission at WebMD Ignite is to revolutionize the healthcare ecosystem by driving action, championing education, and connecting at every touchpoint along the health journey. And everyone at our organization works together to make this happen 

To learn more about the pulse oximeter issue, view these resources below: 

• Pulse Oximeter Market 
• Skin Pigmentation Influence on Pulse Oximetry Accuracy: A Systematic Review and Bibliometric Analysis 
• Racial Bias in Pulse Oximetry Measurement 
• Racial Disparities in Pulse Oximeter Device Inaccuracy and Estimated Clinical Impact on COVID-19 Treatment Course 
• Pulse Oximeter Accuracy and Limitations: FDA Safety Communication 
• Approach for Improving the Performance Evaluation of Pulse Oximeter Devices Taking Into Consideration Skin Pigmentation, Race and Ethnicity 
• November 1, 2022: Anesthesiology and Respiratory Therapy Devices Panel of the Medical Devices Advisory Committee Meeting Announcement