Masimo pulse oximetry found accurate across all skin tones in real-world ICU study

Masimo announced findings from an exploratory analysis of the INSPIRE feasibility study, published in CHEST Critical Care, showing that Masimo SET pulse oximetry performed accurately among critically ill adult patients of all skin tones, including those with low perfusion requiring vasopressors. The study, led by Andrew Goodwin and colleagues at the Medical University of South Carolina (MUSC), reported zero cases of occult hypoxemia—an undetected drop in blood oxygen levels.

Unlike previous accuracy studies conducted under controlled laboratory conditions or using retrospective hospital data, the INSPIRE study was carried out in a real-world hospital environment. Researchers compared arterial blood saturation (SaO₂) values, obtained invasively during routine care, with time-synchronized pulse oximetry readings (SpO₂). The study included 50 patients drawn from a larger planned cohort of 502, representing a full range of skin pigmentation based on validated colorimeter measurements.

Masimo SET demonstrated an overall accuracy of 1.47% root-mean-squared (ARMS), outperforming the typical industry benchmark of 3% ARMS and meeting FDA standards for motion and low-perfusion conditions. The modest median bias between SpO₂ and SaO₂ values—less than 1%—was not clinically significant, and there was no meaningful difference between results for light- and dark-skinned patients. Nearly 40% of the samples were collected during low perfusion, yet no occult hypoxemia events occurred.

Goodwin said the results “demonstrate that we are closer to a definitive answer regarding how the Masimo SET sensor performs in a real-world ICU environment.” Daniel Cantillon, M.D., chief medical officer at Masimo, added: “We’re highly encouraged to see no occult hypoxemia events so far and that the unique INSPIRE study design can prospectively measure that performance in a real-world setting. The reported findings continue to demonstrate top-in-class accuracy.”

Data collection for the full 502-patient study is ongoing.

Pulse oximetry and the equity challenge

Pulse oximeters, which measure blood oxygen saturation noninvasively, became a critical tool during the COVID-19 pandemic—but concerns about their accuracy across different skin tones have persisted. Studies have shown that conventional pulse oximeters can overestimate blood oxygen levels in patients with darker skin, potentially leading to missed cases of hypoxemia. According to a 2022 study in JAMA Internal Medicine, Black patients were nearly three times as likely as white patients to have undetected low oxygen levels when pulse oximetry was used alone.

Regulators and clinicians have pushed for greater scrutiny of device performance across diverse populations. In 2024, the U.S. Food and Drug Administration convened a public meeting to discuss how skin pigmentation, motion, and perfusion affect pulse oximeter readings, emphasizing the need for more inclusive testing protocols.

Masimo’s INSPIRE trial represents a step toward addressing those concerns by using a prospective, real-world approach with rigorous data collection and objective skin-tone measurement. If its full results continue to show parity across pigmentation groups, the findings could help rebuild clinician confidence in pulse oximetry accuracy and inform future device standards.

As the study progresses, researchers hope it will set a new benchmark for how clinical accuracy studies are designed and evaluated, ensuring that life-saving monitoring tools perform equally well for all patients.