Study finds pulse oximeters at Johns Hopkins shifted from overestimating to underestimating oxygen, with larger errors in patients of color

A retrospective analysis of five years of pulse‑oximeter data from Johns Hopkins Hospital shows a shift in measurement bias.

Earlier research documented that the devices tend to overestimate oxygen saturation in people with darker skin, potentially masking hypoxia.

The new study reports that, at higher oxygen levels, the same devices began to underestimate saturation across all patients, with the magnitude of error still greater for patients of color.

These findings highlight that inaccuracies are not limited to skin tone alone and suggest a need for improved sensor technology and calibration standards.