In Feasibility Study for Large, Prospective, Real-World Trial, Masimo SET® Performed Accurately on Critically Ill Adult ICU Patients of All Skin Tones
The INSPIRE Trial Prospectively Assesses Pulse Oximeter Accuracy Using a Unique Real-world Study Design and in the Feasibility Study Showed No Clinically Significant Bias Between Patients with Light and Dark Skin Tones and No Occult Hypoxemia
Masimo (NASDAQ:MASI) today announced the findings of an exploratory analysis for a unique feasibility study published in CHEST Critical Care in which Dr. Andrew Goodwin and colleagues at the Medical University of South Carolina (MUSC) found that Masimo SET® pulse oximetry performed accurately among critically ill adult patients of all skin tones, including those with low perfusion requiring vasopressors – and reported zero occult hypoxemic events.1
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Masimo SET® Pulse Oximetry and RD SET® Sensors
Such accuracy studies are typically conducted in controlled laboratory conditions with healthy volunteers, or using retrospective data from hospitalized patients. For the first time, the authors demonstrated the feasibility of conducting a technically rigorous accuracy study inside a hospital environment where arterial blood saturation (SaO2) values invasively obtained at clinical discretion were compared with time-synchronized pulse oximetry saturation (SpO2) values. This unique design allowed SaO2-SpO2 accuracy comparisons to be made at time points that were clinically indicated – initiated by treatment teams in keeping with established practice, both during routine measurement and when spontaneous changes in a patient's condition necessitated a blood draw – which by definition are important moments to include in any rigorous evaluation of a pulse oximeter's accuracy in real-world use.
Once complete, the MUSC team's work will be the largest study of its kind to prospectively examine pulse oximetry performance and the frequency of occult hypoxemia among critically ill adults across the spectrum of light and dark skin tones in a real-world hospital environment. The findings are consistent with previous laboratory and retrospective hospital-based studies which demonstrated Masimo SET®'s accuracy on patients with both dark and light skin tones, even during low perfusion, without clinically significant bias between groups.2-5
In this analysis, the researchers demonstrated that the technically rigorous and methodologically sound approach of laboratory studies could be applied in a real-world clinical setting, using a unique design referred to as the Investigation of Skin Pigmentation Effect on Performance of Pulse Oximetry, or INSPIRE. Such technical rigor was evaluated using data collected from the first 50 of a planned 502 patients. In this dataset, they found that Masimo SET® pulse oximetry was accurate among patients of all skin tones—well within FDA specifications for laboratory studies—when compared with arterial blood samples. The modest median bias between SpO2 and SaO2 was not clinically significant, and nor was there a clinically significant difference between the median biases for light and dark skin tone patients.
The authors set out to design a study that would address the limitations and methodologic shortcomings often observed in other studies. These include self-reported race as a surrogate for skin pigmentation, retrospective designs that preclude detailed assessment, lag times between SpO2 and SaO2 collection, inability to specify or standardize sensors or device models, and failure to confirm adequate SpO2 signal quality. Laboratory studies performed in healthy volunteers, while technically rigorous, are often conducted without typical real-world accuracy confounders, such as patient motion, low perfusion related to underlying critical illness, medical comorbidities such as anemia, and more. Collectively, the authors note, these limitations "inhibit the ability to make conclusions about the impact of skin pigmentation on device accuracy." By contrast, INSPIRE was "designed to overcome these challenges while examining the clinically relevant outcome of occult hypoxemia [a condition in which dangerously low oxygen saturation is not reflected in pulse oximetry readings] in a population vulnerable to this diagnostic error."
In the present analysis, the researchers enrolled 107 adult patients at two ICUs within the MUSC main hospital from January to July 2024, which yielded a sample size of 50 patients who had at least one clinically indicated blood draw collected while the study team was present. Skin pigmentation was assessed using a validated noninvasive hand-held skin colorimeter, with patients grouped into dark and light skin tone categories based on individual topology angle (ITA). SpO2 readings were collected using Masimo RD SET® sensors connected to Rad-97® Pulse CO-Oximeters®.
From among the 50 patients and 84 blood samples in the sample size, the researchers found that 80 paired SpO2-SaO2 readings from 49 patients met their technical criteria for inclusion. The patients also met INSPIRE's skin pigmentation requirement, representing a wide range of ITA measurements and all 6 ITA categories. 26 of the 50 patients were classified as having dark skin pigmentation, with 41 data pairs from patients with dark skin tone and 39 from patients with light skin tone. 31 data pairs (39%) were collected from patients during low perfusion (< 1.4%).
The researchers found that, among the 49 patients and 80 data pairs, Masimo SET® pulse oximetry had overall accuracy of 1.47% root-mean-squared (ARMS*), in keeping with the FDA accuracy specification for Masimo RD SET® sensors in no motion and motion conditions, 1.5% ARMS, and significantly outperforming the industry-standard specification of 3% ARMS.6 The median bias between noninvasive SpO2 and invasive SaO2 was -0.6%, which is not clinically significant. There was a modest, statistically but not clinically significant, difference of 0.7% between the median bias for dark skin tone and light skin tone patients (-0.2% vs. -0.9%; p=0.0004). While nearly half of the data pairs were collected from subjects at risk of occult hypoxemia, zero occult hypoxemic events occurred.
The researchers concluded that the INSPIRE trial "can feasibly enroll critically ill patients across the full spectrum of skin pigmentation while facilitating precise data collection using standard-of-care workflows in an ICU setting," noting that "[t]hese data support the study's feasibility in a real-world clinical setting, and the appropriateness of the chosen methods."
Data collection for the full INSPIRE trial is still in progress. In the full study, the result of which the researchers hope to publish next year, they will investigate and analyze the effect of skin pigmentation on pulse oximeter accuracy across the complete dataset, including a comparison of occult hypoxemia rates between patients with dark and light skin tones.
Andrew Goodwin, M.D., Principal Investigator and Section Chief of Critical Care at MUSC, commented, "Masimo SET® was chosen for our INSPIRE trial because of its industry-leading accuracy. We are pleased to add to the growing body of evidence for pulse oximetry research in varying skin tones. Our feasibility study has demonstrated that we are closer to a definitive answer regarding how the Masimo SET® sensor performs in a real-world ICU environment. Although not yet definitive, our preliminary results suggest that Masimo SET® performs accurately on all skin tones."
Daniel Cantillon, M.D., Chief Medical Officer at Masimo, added, "The concern for dangerously overestimating blood oxygen levels with pulse oximetry is greatest among critically ill and poorly perfused patients with dark skin tone who are often moving. 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. We look forward to the results of the full study."
@Masimo | #Masimo
*ARMS accuracy is a statistical calculation of the difference between device measurements and reference measurements. Approximately two-thirds of the device measurements fell within +/- ARMS of the reference measurements in a controlled study.
References
- Travers A, Terry C, Merrell W, Heincelman M, Warden A, Goodwin A. INSPIRE: Feasibility of a Study Examining the Effect of Skin Pigment on Pulse Oximetry. CHEST Crit Care. 10 Sept 2025. DOI: 10.1016/j.chstcc.2025.100209.
- Sharma V, Barker S, Sorci R, Park L, Wilson W. Racial effects on Masimo pulse oximetry: impact of low perfusion index. J Clin Monit Comput. 19 Jan 2024. https://doi.org/10.1007/s10877-023-01113-2.
- Barker SJ, Wilson WC. Racial effects on Masimo pulse oximetry: a laboratory study. J Clin Monit Comput. 2023 Apr;37(2):567-574. https://doi.org/10.1007/s10877-022-00927-w.
- Foglia EE, Whyte RK, Chaudhary A, Mott A, Chen J, Propert KJ, Schmidt B. The Effect of Skin Pigmentation on the Accuracy of Pulse Oximetry in Infants with Hypoxemia. J Pediatr. 2017 Mar;182:375-377.e2. https://doi.org/10.1016/j.jpeds.2016.11.043.
- Marlar AI, Knabe BK, Taghikhan Y, Applegate RL, Fleming NW. Performance of pulse oximeters as a function of race compared to skin pigmentation: a single center retrospective study. J Clin Monit Comput. 2025 Feb;39(1):119-125. https://doi.org/10.1007/s10877-024-01211-9.
- FDA. Guidance for Industry: Pulse Oximeters for Medical Purposes - Non-Clinical and Clinical Performance Testing, Labeling, and Premarket Submission Recommendations. January 2025.
About Masimo
Masimo (NASDAQ:MASI) is a global medical technology company that develops and produces a wide array of industry-leading monitoring technologies, including innovative measurements, sensors, patient monitors, and automation and connectivity solutions. Our mission is to improve life, improve patient outcomes, reduce the cost of care, and take noninvasive monitoring to new sites and applications. Masimo SET® Measure-through Motion and Low Perfusion™ pulse oximetry, introduced in 1995, has been shown to outperform other pulse oximetry technologies in over 100 independent and objective studies, which can be found at www.masimo.com/evidence/featured-studies/feature. Masimo SET® is estimated to be used on more than 200 million patients around the world each year and is the primary pulse oximetry at all 10 top U.S. hospitals as ranked in the 2025 Newsweek World's Best Hospitals listing. Additional information about Masimo and its products may be found at www.masimo.com.
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This press release includes forward-looking statements as defined in Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, in connection with the Private Securities Litigation Reform Act of 1995. Forward-looking statements are statements other than statements of historical facts that address activities, events or developments that we expect, believe or anticipate will or may occur in the future. These forward-looking statements include, among others, statements regarding the outcome of future studies evaluating the real world performance of Masimo SET®; and other matters that do not relate strictly to historical facts or statements of assumptions underlying any of the foregoing. These statements are often identified by the use of words such as "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "on-going," "opportunity," "plan," "potential," "predicts," "forecast," "project," "seek," "should," "will," or "would," the negative versions of these terms and similar expressions or variations, but the absence of such words does not mean that a statement is not forward-looking. These forward-looking statements are based on current expectations about future events affecting us and are subject to risks and uncertainties, all of which are difficult to predict and many of which are beyond our control and could cause our actual results to differ materially and adversely from those expressed in our forward-looking statements as a result of various risk factors, including, but not limited to: the ability for clinical studies to recruit eligible participants; the ability for the investigator to collect meaningful data; the design of the clinical protocol; and other factors discussed in the "Risk Factors" section of our most recent periodic reports filed with the Securities and Exchange Commission ("SEC"), including our most recent Form 10-K and Form 10-Q, all of which you may obtain for free on the SEC's website at www.sec.gov. Forward-looking statements are not guarantees of future performance. Although we believe that the expectations reflected in our forward-looking statements are reasonable, we do not know whether our expectations will prove correct. All forward-looking statements included in this press release are expressly qualified in their entirety by the foregoing cautionary statements. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of today's date. We do not undertake any obligation to update, amend or clarify these statements or the "Risk Factors" contained in our most recent reports filed with the SEC, whether as a result of new information, future events or otherwise, except as may be required under the applicable securities laws.
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