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Broad-linewidth sources result in a skin-tone bias in noninvasive optical measurement of oxygen saturation

Year: 2026
Type: article
Abstract: Significance: Pulse oximeters overestimate arterial oxygen saturation in patients with darker skin tones, potentially increasing rates of occult hypoxemia. The emission of broad-linewidth light-emitting diodes (LEDs) has been proposed as a possible cause for this melanin-dependent bias. Aim: This letter utilizes a physics-based model to investigate if the spectral bandwidth of light sources contributes to melanin-dependent measurement biases. Approach: Pulse oximetry measurements were simulated across varying melanin concentrations and source bandwidths using a hybrid diffusion theory and Monte Carlo model. Epidermal melanin absorption was modeled with transmissive filters on the surfaces of an infinite slab representing bulk tissue. Results: Simulations demonstrate that pulse oximeter calibration curves depend on melanin concentration when broad-linewidth LEDs are utilized. Conversely, calibration curves remain independent of melanin when employing monochromatic laser diodes (LDs). Conclusion: Spectral coloring from broad-linewidth LEDs contributes to the skin-tone bias observed in pulse oximetry. Although updating calibration methods for different skin tones is a potential approach, adopting monochromatic LDs could alternatively eliminate this spectral-coloring contribution to the bias.
DOI: 10.1117/1.jbo.31.7.070501
Institution: Tufts University
Language: English
Open Access status: gold
Estimated APC paid: $1,675
OpenAlex ID: W7167807068
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