Pulse Oximetry & Racial Bias

The Full Story

This page is focused on the bias of pulse oximetry which measures oxygen and the implications for sleep disorder testing and treatment.

Note: Do NOT discontinue any treatment based on information on this page and site. Consult with your physician BEFORE you make any changes to your treatment.

Introduction:

What is Pulse Oximetry and Why Does it Matter?

Pulse oximeters estimate blood oxygen saturation (SpO₂) using light absorption through the skin. Accurate readings are essential for:

Diagnosing and monitoring sleep apnea
Managing heart failure, COPD, and pneumonia
Determining need for oxygen therapy or hospitalization
Monitoring during anesthesia or critical care

In sleep medicine, oxygen levels determine apnea severity, treatment eligibility, and even insurance coverage for CPAP machines or oxygen support.

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The Problem: Skin Tone Affects Accuracy

Pulse oximeters work by shining light through the skin to estimate blood oxygen levels (SpO₂), but melanin—present in higher amounts in darker skin—can interfere with this light absorption, leading to falsely high readings. This discrepancy means that people with darker skin tones are more likely to have low oxygen levels go undetected, a condition known as occult hypoxemia.

Key Studies:

Sjoding et al. (2020, New England Journal of Medicine)
- This landmark study analyzed paired pulse oximeter and arterial blood gas readings and found that Black patients had nearly three times the frequency of occult hypoxemia (SpO₂ >92% on pulse ox but PaO₂ <88 mm Hg on arterial blood gas) compared to white patients.
- “In two large cohorts, Black patients had significantly higher odds of occult hypoxemia not detected by pulse oximetry.”
Fawzy et al. (2022, JAMA)
- A retrospective study of patients hospitalized with COVID-19 found that pulse oximetry overestimated oxygen saturation in Black, Hispanic, and Asian patients, resulting in delayed or reduced delivery of supplemental oxygen, and ultimately contributing to worse clinical outcomes.
- “Compared with white patients, Black and Hispanic patients had lower odds of timely identification of eligibility for COVID-19 therapies and higher odds of unrecognized need for supplemental oxygen.”
Valbuena et al. (2022, BMJ)
- This study confirmed that racial and ethnic discrepancies in pulse oximeter readings are associated with delays in care. Black and Hispanic patients were more likely to have hypoxemia that went undetected, resulting in delayed recognition and treatment.
- “Racial and ethnic disparities in the accuracy of pulse oximetry led to differences in clinical outcomes.”

Why Is This A Problem

1. Delayed or Missed Diagnosis

Hypoxemia (low oxygen levels in the blood) can go undetected in patients with darker skin tones because pulse oximeters may provide falsely high readings
This can result in delays in initiating life-saving treatments, such as oxygen therapy or mechanical ventilation

2. Inequities in Care

Patients with undiagnosed or underestimated hypoxemia may receive less aggressive treatment or be deprioritized for care
These inaccuracies can exacerbate existing health disparities, particularly in respiratory conditions like COVID-19, asthma, or chronic obstructive pulmonary disease (COPD)

3. Worsened Clinical Outcomes

Inaccurate readings can lead to under-treatment, which may result in poorer health outcomes, such as organ damage, prolonged illness, or even death, especially in acute conditions like pneumonia or sepsis

4. Disparities in Research and Trials

Clinical trials and studies relying on pulse oximetry for patient monitoring might inadvertently include inaccurate data for participants with darker skin tones, skewing results and potentially leading to ineffective or biased medical guidelines

5. Erosion of Trust

Recognition of racial bias in medical devices like pulse oximeters can undermine trust in healthcare systems, particularly among historically underserved populations

6. Economic and Systemic Costs

Misdiagnosis or delayed care can increase healthcare costs due to longer hospital stays, more intensive interventions, or litigation related to inadequate treatment

Addressing the Bias

Efforts to address this issue include:

Improving the design and calibration of pulse oximeters to ensure accuracy across all skin tones
Educating clinicians about the limitations of these devices and encouraging supplemental methods for assessing oxygen levels
Implementing policies that require more rigorous testing of medical devices in diverse populations

The goal is to mitigate these biases to ensure equitable healthcare for all patients.

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History of Skin Bias in Pulse Oximetry: This Isn't A New Problem

Sleep physicians have been aware of pulse ox bias for years. Yet, despite its wide usage, this issue has received little attention outside sleep medicine and critical care. Until the COVID-19 pandemic forced a spotlight on disparities, pulse oximetry bias remained largely ignored in primary care, cardiology, and public health.Even today, most pulse oximeters on the market are not calibrated for darker skin tones, and there are no standard regulatory guidelines requiring skin-tone-inclusive testing. The following is a concise timeline of the evolving awareness:

1980s -1990s: The initial development and testing of pulse oximeters predominantly involved individuals with lighter skin tones. Researchers observed variations in accuracy among different skin types, but these findings were not widely acknowledged or addressed during this period
Early 2000s: Research began to reveal that pulse oximeters exhibited reduced accuracy in individuals with darker skin pigmentation. A notable study published in Anesthesia & Analgesia in 2005 indicated that these devices often overestimated oxygen saturation levels in patients with darker skin
2010s: The topic received increased attention in academic literature, although it remained insufficiently recognized in clinical settings. Studies conducted during this decade consistently validated the discrepancies in pulse oximetry readings related to skin pigmentation
2020: The COVID-19 pandemic underscored the essential function of pulse oximetry in monitoring oxygen saturation. A landmark study published in The New England Journal of Medicine in December 2020 provided compelling evidence that pulse oximeters were more likely to overlook hypoxemia in Black patients compared to their white counterparts. This research ignited widespread discourse regarding racial bias in medical devices

Cardiac and Sleep Implications

In Sleep Medicine

Misleading oximeter readings may underestimate apnea severity, leading to underdiagnosis or denial of CPAP coverage in communities of color
Sleep studies often use oxygen desaturation events to score apnea severity, so bias in this measurement can result in missed or downplayed diagnoses

In Cardiology and Critical Care

Patients of color may be under-treated for hypoxemia-related heart failure or arrhythmias
Delayed oxygen therapy can contribute to longer hospital stays, greater cardiac strain, and higher mortality
During anesthesia or sedation, oxygen monitoring is essential—inaccurate readings increase perioperative risk

Why This Matters for Underserved Populations

Communities already facing barriers to care, including Black, Hispanic, Indigenous, and uninsured patients, are more likely to rely on pulse oximetry in outpatient or home settings due to limited access to labs or specialists. When these readings are inaccurate:

Sleep apnea may go undiagnosed or undertreated
Oxygen therapy may be withheld
Symptoms may be dismissed as anxiety or fatigue
Patients may deteriorate at home, increasing risk of emergency events or death

This bias further entrenches existing health disparities in cardiovascular disease, respiratory conditions, and sleep disorders.

What Can Be Done

For Patients:

If you’re Black, Hispanic, or have darker skin and are undergoing a sleep study or oxygen monitoring, ask how your care team is accounting for pulse oximetry bias
If you’re using a home pulse oximeter, be aware that a reading of 92–94% may not reflect your true oxygen level. Advocate for arterial blood gas testing or additional monitoring if you’re symptomatic
Push for sleep studies that evaluate symptoms alongside oxygen data, not just tech thresholds

For Providers and Health Systems:

Screen for sleep disorders based on symptoms, not just oximetry data
Include a question about skin tone bias in quality reviews of sleep studies and post-op care
Advocate for FDA regulations requiring racially inclusive testing and transparency from pulse oximeter manufacturers
Educate clinicians across specialties, not just pulmonologists or sleep physicians, on this critical issue

Conclusion

Pulse oximetry bias is not just a technical flaw, it’s a systemic barrier to accurate diagnosis and safe treatment for communities of color. It affects sleep care, heart health, and even survival in critical situations. Until this bias is widely acknowledged and addressed, it will continue to contribute to preventable disparities in outcomes. At the Sleep Equity Project, we’re committed to raising awareness, promoting better standards, and empowering patients to advocate for equitable care.