New Study Investigates the Utility of Masimo ORi(TM), Oxygen Reserve Index, As an Indicator to Avoid Hyperoxia During General Anesthesia

Masimo (NASDAQ: MASI) announced today that in a study recently published in the Journal of Clinical Monitoring and Computing, researchers investigated the ability of Masimo ORi™ (Oxygen Reserve Index) to serve as a noninvasive indicator of the arterial partial pressure of oxygen (PaO₂) during general anesthesia, to help avoid hyperoxia.¹ ORi is an index of oxygenation in the moderate hyperoxic region (PaO₂ range of 100 to 200 mmHg). As an “index” with a scale between 0.0 and 1.0, ORi can be trended to notify clinicians of changes in a patient’s oxygen reserve.

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Masimo Root® with Radical-7® and ORi™ (Photo: Business Wire)

Dr. Keisuke Yoshida and colleagues at the Fukushima Medical University School of Medicine in Japan sought to evaluate whether ORi could provide continuous, noninvasive insight into avoiding excessive hyperoxia by comparing the relationship between PaO₂ and ORi during various oxygen administration conditions. They enrolled 20 patients scheduled for surgery requiring general anesthesia. ORi was measured using Masimo Root^® with the Radical-7^® Pulse CO-Oximeter^® and rainbow^® sensors. PaO₂ was measured using the Siemens RAPIDLab^® 1265 blood gas analyzer. For each patient, after inducing anesthesia, blood gas analysis to measure PaO₂ was performed four times, with ORi values recorded each time blood was drawn, providing 80 data sets. Initial analysis was performed with inspired oxygen concentration (FiO₂) set to 0.33, with the three subsequent analyses performed when ORi was around 0.5, 0.2, and 0, achieved by adjusting FiO₂.

For analysis, the researchers chose an upper PaO₂ threshold of 240 mmHg, based on a previous study that found a positive correlation between ORi and PaO₂ when PaO₂ < 240 mmHg.² They defined hyperoxemia as PaO₂ ≥ 150 mmHg. Using linear regression analysis, the researchers found a “relatively strong” positive correlation (r² = 0.706) between ORi and PaO₂ when PaO₂ was less than 240 mmHg. Using receiver operating characteristic (ROC) curve analysis, they calculated that the optimal cut-off ORi value to detect PaO₂ ≥ 150 mmHg was 0.21 (sensitivity 0.950, specificity 0.755). Using four-quadrant plot analysis, they found that ORi trended PaO₂ with a 100% concordance rate.

The researchers concluded that “Hyperoxemia can be detected by observing ORi of patients under general anesthesia, and thus unnecessary administration of high concentration oxygen can possibly be avoided.” They also noted, “ORi has unique characteristics reflecting the state of oxygenation in the hyperoxic range. The present study examined data under general anesthesia in the operating room, but ORi’s unique features can provide benefits not only in the operating room, but also in the ICU and other fields. In the future, in order to make the most use of ORi, further clinical study is required.”

As study limitations, the researchers noted the small number of subjects in the study. In addition, they noted, “It is plausible that a given patient’s factors (e.g. age, physique, body temperature, finger perfusion, hemoglobin concentration) affect their ORi value. Therefore, ORi might not reflect all changes in PaO₂.”

ORi has not received FDA 510(k) clearance and is not available for sale in the United States.

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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 patient outcomes and reduce the cost of care. Masimo SET^® Measure-through Motion and Low Perfusion™ pulse oximetry, introduced in 1995, has been shown in over 100 independent and objective studies to outperform other pulse oximetry technologies.³ Masimo SET^® has also been shown to help clinicians reduce severe retinopathy of prematurity in neonates,⁴ improve CCHD screening in newborns,⁵ and, when used for continuous monitoring with Masimo Patient SafetyNet™ in post-surgical wards, reduce rapid response team activations, ICU transfers, and costs.^6-8 Masimo SET^® is estimated to be used on more than 100 million patients in leading hospitals and other healthcare settings around the world,⁹ and is the primary pulse oximetry at 9 of the top 10 hospitals listed in the 2018-19 U.S. News and World Report Best Hospitals Honor Roll.¹⁰ Masimo continues to refine SET^® and in 2018, announced that SpO₂ accuracy on RD SET™ sensors during conditions of motion has been significantly improved, providing clinicians with even greater confidence that the SpO₂ values they rely on accurately reflect a patient’s physiological status. In 2005, Masimo introduced rainbow^® Pulse CO-Oximetry technology, allowing noninvasive and continuous monitoring of blood constituents that previously could only be measured invasively, including total hemoglobin (SpHb^®), oxygen content (SpOC™), carboxyhemoglobin (SpCO^®), methemoglobin (SpMet^®), Pleth Variability Index (PVi^®), RPVi™ (rainbow^® PVi), and Oxygen Reserve Index (ORi™). In 2013, Masimo introduced the Root^® Patient Monitoring and Connectivity Platform, built from the ground up to be as flexible and expandable as possible to facilitate the addition of other Masimo and third-party monitoring technologies; key Masimo additions include Next Generation SedLine^® Brain Function Monitoring, O3^® Regional Oximetry, and ISA™ Capnography with NomoLine^® sampling lines. Masimo’s family of continuous and spot-check monitoring Pulse CO-Oximeters^® includes devices designed for use in a variety of clinical and non-clinical scenarios, including tetherless, wearable technology, such as Radius-7^® and Radius™ PPG, portable devices like Rad-67™, fingertip pulse oximeters like MightySat^® Rx, and devices available for use both in the hospital and at home, such as Rad-97™. Masimo hospital automation and connectivity solutions are centered around the Iris^® platform, and include Iris Gateway™, Patient SafetyNet, Replica™, Halo ION™, UniView™, and Doctella™. Additional information about Masimo and its products may be found at www.masimo.com. Published clinical studies on Masimo products can be found at www.masimo.com/evidence/featured-studies/feature/.

ORi and RPVi have not received FDA 510(k) clearance and are not available for sale in the United States. The use of the trademark Patient SafetyNet is under license from University HealthSystem Consortium.

References

1. Yoshida K, Isosu T, Noji Y, Ebana H, Honda J, Sanbe N, Obara S, Murakawa M. Adjustment of oxygen reserve index (ORi™) to avoid excessive hyperoxia during general anesthesia. JCMC. 2019. https://doi.org/10.1007/s10877-019-00341-9.
2. Applegate R, Dorotta I, Wells B, Juma D, Applegate P. The relationship between oxygen reserve index and arterial partial pressure of oxygen during surgery. Anesth Analg. 2016;123:626–33. https ://doi.org/10.1213/ANE.00000 00000 00126 2.
3. Published clinical studies on pulse oximetry and the benefits of Masimo SET^® can be found on our website at http://www.masimo.com. Comparative studies include independent and objective studies which are comprised of abstracts presented at scientific meetings and peer-reviewed journal articles.
4. Castillo A et al. Prevention of Retinopathy of Prematurity in Preterm Infants through Changes in Clinical Practice and SpO₂ Technology. Acta Paediatr. 2011 Feb;100(2):188-92.
5. de-Wahl Granelli A et al. Impact of pulse oximetry screening on the detection of duct dependent congenital heart disease: a Swedish prospective screening study in 39,821 newborns. BMJ. 2009;Jan 8;338.
6. Taenzer AH et al. Impact of pulse oximetry surveillance on rescue events and intensive care unit transfers: a before-and-after concurrence study. Anesthesiology. 2010:112(2):282-287.
7. Taenzer A et al. Postoperative Monitoring – The Dartmouth Experience. Anesthesia Patient Safety Foundation Newsletter. Spring-Summer 2012.
8. McGrath SP et al. Surveillance Monitoring Management for General Care Units: Strategy, Design, and Implementation. The Joint Commission Journal on Quality and Patient Safety. 2016 Jul;42(7):293-302.
9. Estimate: Masimo data on file.
10. http://health.usnews.com/health-care/best-hospitals/articles/best-hospitals-honor-roll-and-overview.

Forward-Looking Statements

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. These forward-looking statements include, among others, statements regarding the potential effectiveness of Masimo ORi^™. 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: risks related to our assumptions regarding the repeatability of clinical results; risks related to our belief that Masimo's unique noninvasive measurement technologies, including Masimo ORi, contribute to positive clinical outcomes and patient safety; risks related to our belief that Masimo noninvasive medical breakthroughs provide cost-effective solutions and unique advantages; as well as other factors discussed in the "Risk Factors" section of our most recent reports filed with the Securities and Exchange Commission ("SEC"), which may be obtained for free at the SEC's website at www.sec.gov. 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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