Masimo touts study showing its pulse oximeters are effective across skin tones regardless of perfusion levels

About a week after the FDA convened its latest meeting to discuss strategies for reducing racial biases in widely available pulse oximetry technology, Masimo has released new study data suggesting that such measures won’t be needed for its own blood oxygen sensors.

The new results build on previous analyses of the same data set, comprising 39 Black patients and 36 white patients who repeatedly used Masimo’s SET pulse oximeters—alongside arterial blood gas measurements for comparison—between 2015 and 2021, for a total of more than 7,000 paired readings.

And, as with the study’s previous findings, according to Masimo’s announcement late last week, the latest round of results uphold the company’s claim that its pulse oximeters churn out readings with no significant difference in quality based on a user’s skin tone.

In the latest retrospective analysis, the study’s investigators paid particular attention to each patient’s perfusion pressure, denoting how effectively blood is being pushed throughout the body. They separated the participants into “normal perfusion” and “low perfusion” groups based on their perfusion index (Pi) values.

Overall, among those with normal perfusion, Masimo’s devices returned blood oxygen readings that differed from the comparative arterial blood gas measurements by an average of just 0.18%. Broken down by race, the Black participants’ readings differed from the comparisons by an average of -0.26%, while the white subjects saw a difference of -0.12%.

In the low perfusion group, meanwhile, the average difference between the paired readings was 0.48%, which shook out to a 0.91% average fluctuation for white patients with low perfusion and a difference of just 0.19% for the subset’s Black participants.

“Masimo SET pulse oximeters with RD SET sensors are accurate for individuals of both Black and White races when Pi is normal, as well as during conditions when Pi is low,” the study’s authors concluded, adding that the accuracy levels of their findings were “well within FDA standards.”

They did note that “this study was conducted in healthy volunteers during well-controlled laboratory desaturations, and results could vary under certain challenging clinical conditions,” but added that the confounding factors they’d controlled for—including abnormal hemoglobin species—“were similar (statistically the same) between Black and White groups.”

The new analysis comes a little over a year after Masimo first reported results from the 75-patient cohort. In November 2022, it published study data calculating how its SET devices had performed among Black and white patients without taking perfusion levels into account.

That analysis concluded that, overall, the Black participants’ readings differed from the benchmark arterial blood gas measurements by an average of 1.42%, compared to 1.35% for the white patients.

The Masimo executives leading the study said at the time that the company’s pulse oximeters are able to avoid the significant racial bias of competing devices because they were developed and validated using “nearly equal numbers” of subjects with dark and light skin tones and because the SET devices contain additional signal processing engines on top of the traditional red and infrared light-based mechanism of other pulse oximeters.