Authors: Starnes, Joseph R. et al.
Anesthesiology, August 29, 2025. DOI: 10.1097/ALN.0000000000005738
This prospective study investigated how skin tone affects the accuracy of near-infrared spectroscopy (NIRS) measurements in children undergoing cardiac catheterization. Although prior evidence shows that pulse oximetry tends to overestimate oxygen saturation in patients with darker skin tones, the influence of skin pigmentation on NIRS performance has been less well characterized.
The study enrolled 110 patients under 21 years of age. Each participant’s skin tone was quantified objectively using spectrophotometry and categorized by individual typology angle (ITA). Regional cerebral oxygen saturation readings from a Medtronic INVOS 5100C NIRS monitor were compared with mixed venous oxygen saturation obtained during catheterization. Statistical analysis using multivariable linear regression assessed the relationship between ITA and NIRS bias.
Results demonstrated that darker skin tones significantly increased the negative bias of NIRS measurements. Patients with ITA categories 5–6 (darkest skin) had a mean bias of –12.8%, compared to –2.5% for intermediate tones (ITA 3–4) and +0.3% for light tones (ITA 1–2). The difference in bias between the darkest and lightest categories exceeded 13%, a statistically and clinically meaningful discrepancy. ITA remained an independent predictor of measurement error in multivariable models (coefficient 0.173, p<0.001).
The findings indicate that current NIRS technology underestimates regional oxygen saturation in individuals with darker skin, mirroring disparities already documented with pulse oximetry. Such systematic bias could contribute to unequal clinical decision-making and outcomes, particularly in pediatric cardiac care.
What You Should Know:
NIRS monitoring using the INVOS 5100C system demonstrates significant skin tone–related bias, with darker skin tones leading to underestimation of oxygen saturation compared to invasive mixed venous measures. These results underscore the urgent need for improved device calibration and validation standards to ensure equitable performance across all skin tones.
Thank you to Anesthesiology for publishing this important work advancing awareness of racial and technological inequities in perioperative monitoring.