Cause, effect, and remediation of melanin-associated bias in pulse oximetry

Black patients are at greater risk than White patients for occult hypoxemia due to a melanin-associated bias in ${\mathrm{SpO}}_2$ readings from commercially available pulse oximeters that employ polychromatic light sources.

We aim to demonstrate how melanin-associated inaccuracies in commercially available pulse oximeters increase the likelihood of occult hypoxemia for all patients and how monochromatic light sources could minimize melanin-associated occult hypoxemia.

Published values of mean error ( $M$ $[{\mathrm{SpO}}_2-{\mathrm{SaO}}_2]$ ) and uncertainty (SD $[{\mathrm{SpO}}_2-{\mathrm{SaO}}_2]$ ) for Black and White patients were used to analytically model the risk of occult hypoxemia. Mean errors and uncertainties were also estimated for hypothetical patients with no skin melanin, which are directly comparable to values for pulse oximeters employing monochromatic light sources.

The analytically predicted risk of occult hypoxemia for Black patients relative to White patients was 2.1, consistent with published empirical findings. Oximeters unaffected by melanin in the skin would have smaller mean errors and uncertainties than current oximeters, significantly reducing the risk of occult hypoxemia in both Black patients (83% reduction) and White patients (65% reduction).

Because everyone has melanin in their skin, the use of monochromatic light sources in pulse oximeters could significantly reduce the risk of occult hypoxemia for everyone.