Introduction

Recent groundbreaking research presented at the American College of Cardiology (ACC) 2025 Annual Scientific Sessions has revealed unsettling disparities in the accuracy of pulse oximeters based on skin pigmentation. The EquiOx study, a comprehensive real-world investigation involving critically ill adults, found significant differences between pulse oximeter estimates of blood oxygen saturation levels and traditional arterial blood measurements, raising alarm bells for healthcare providers.

Study Design

The study employed a rigorous approach, enrolling 631 patients with an average age of 62 from the Zuckerberg San Francisco General Hospital's intensive care unit between 2022 and 2024. Participants represented a diverse demographic: one-quarter identified as White, another quarter as Hispanic, one-fifth as Black, and one-fifth as Asian. Skin pigmentation was meticulously measured using the Monk Skin Tone Scale alongside objective assessments of melanin content with a spectrophotometer.

Findings

In a striking finding, while the overall pulse oximeter readings tended to underestimate blood oxygen levels, those with darker skin pigmentation frequently experienced less negative bias and a higher risk of overestimation. This indicates that pulse oximeters, a staple in emergency care settings for monitoring oxygen levels, do not deliver consistent accuracy across different skin tones. Dr. Carolyn Hendrickson, an associate professor of medicine at the University of California, San Francisco, highlighted that this could lead to critical health risks, especially if a patient with dangerously low oxygen saturation goes undetected due to false reassurances provided by these devices.

Clinical Implications

Interestingly, the study noted that around 20% of pulse oximeter observations produced an overestimation of oxygen saturation, particularly among individuals with darker skin tones. This has profound implications for clinical decision-making, as accurate blood oxygen readings are crucial for determining treatment options, including the necessity for supplemental oxygen or hospitalization.

Contextual Background

During the COVID-19 pandemic, this topic gained traction as healthcare providers noted that pulse oximeter inaccuracies potentially led to false comfort for critically ill patients. Investigators accounted for over 30 variables that could influence blood oxygen levels, including demographics, medical history, and physical characteristics. Despite these controls, the trends indicating a bias towards underestimations in blood oxygen readings remained consistent, with darkly pigmented individuals still at a higher risk of overestimation.

Call for Future Research

The findings spotlight an urgent need for future research that includes a more representative sample of patients with darker skin tones and examines how pulse oximeter accuracy varies at lower oxygen saturation levels. Dr. Hendrickson emphasized the critical distinction between race as a social construct and skin pigmentation, advocating for the integration of skin pigment data in clinical settings to ensure equitable health outcomes.

Conclusion

As this vital research unfolds, it calls into question the reliability of pulse oximeters—commonly used in both hospital settings and home care—urging healthcare providers to rethink protocols that rely heavily on these devices for monitoring patients' oxygen status, especially among populations that may be disproportionately affected. With a growing understanding of health disparities, it is essential that advancements in medical technology adequately address the needs of all patients, promoting fairness in healthcare practices.