Chances are, you’ve worn a pulse oximeter. It’s a nifty little device that gently clips to a small body part, typically the end of your index finger, and unobtrusively records your heart rate and oxygen saturation level. You get near instantaneous readings of each metric on the small LED screen and your providers use this information to record a snapshot of your vitals, to monitor your condition, or to help diagnose acute conditions, like a pulmonary embolism. Essentially, the device uses a red light and an infrared light to measure the oxygen levels in a patient’s blood. It turns out, though, it may not treat all patients equally. So, is your pulse oximeter racist?

A recent study that appeared in the New England Journal of Medicine demonstrated that Black patients see a hugely disproportionate rate of misleading readings compared to white patients. The study compared pulse oximeter readings in Black and white patients with results from arterial blood gas tests, which are done via blood draw. The researchers found that the pulse oximeter was three times as likely to return a higher O2 saturation rate than the blood gas test. This means that in those patients, their conditions were actually worse than what was being reflected on the oximeter. An inaccurate reading may lead to a doctor discharging a patient that should stay for observation, or a condition falling off the doctor’s differential diagnosis. It is not a stretch to recognize that these patients were headed towards worse outcomes if not for the results of their blood gas tests.

So, what gives? Darker skin pigment appears to provide less accurate readings, just as cold fingers and nail polish affect the ability of the tiny lights to make accurate measurements. Was this considered when the devices were being developed? And what sort of warnings do providers have?

These results may help to demonstrate some of the racial disparity in medical device development and, in turn, disparate treatment among racial groups. You may have read some of our prior coverage regarding the lower quality of care, generally, that populations of color receive in the United States.

This study comes fifteen years after some of the first questions were being asked about whether pulse oximeters were developed with populations that were not adequately diverse. If a device is meant to be used equally among all population groups, then why not test it that way? This inadequate use of testing populations becomes one of the pieces in the giant puzzle for why people of color receive lower quality of care, and have poorer outcomes on average.