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Study Finds Masimo PVI Beneficial in Identifying Patients At-Risk for Developing Anesthesia-Induced Hypotension

Researchers Show Linkage Between Pre-Anesthesia PVI Levels and the Magnitude of Blood Pressure Reduction During Anesthesia Induction

IRVINE, Calif., May 21, 2010 /PRNewswire via COMTEX/ --Masimo (Nasdaq: MASI), the inventor of Pulse CO-Oximetry(TM) and Measure-Through Motion and Low Perfusion pulse oximetry, announced today that a new clinical study published in the May 2010 issue of Acta Anaesthesiologica Scandinavica shows that Masimo pleth variability index (PVI) can be used to help clinicians assess risk for mean arterial pressure (MAP) decreases and subsequent hypotension during anesthesia administration. Researchers concluded that PVI may be "useful to identify patients at high risk for developing severe hypotension during anesthesia induction", allowing "anesthesiologists to adopt preventive measures to ensure greater patient safety."(1,2)

Hypotension (abnormally low blood pressure) during anesthesia induction is a common event that can deprive tissues of adequate oxygen delivery. Severe or sustained hypotension can result in brain, heart, and organ damage -- making prompt identification and treatment during the induction period critically important. The ability to properly identify patients at-risk for hypotension could help anesthesiologists to plan preventive strategies to reduce patient risk and ensure safer inductions. Anesthesia-induced hypotension is linked to both patient volume status and vascular tone, and previous studies have shown PVI's association with these physiologic changes.

In the study, researchers from the Osaka City University Medical School in Japan measured PVI (via the Masimo Radical-7 Pulse CO-Oximeter), heart rate (HR), and blood pressure [systolic blood pressure (SBP), diastolic blood pressure (DBP), and MAP] in 76 healthy adult surgical patients at 30-second intervals before and during anesthesia induction (bolus administration of 1.8 mg/kg propofol and 0.6 mg/kg rocuronium). Analysis demonstrated that HR, SBP, DBP, and MAP were significantly decreased after anesthesia administration by 8.5%, 33%, 23%, and 26%, respectively. Pre-anesthesia PVI, which ranged from 7 to 28 with a mean value of 16 +/- 5.5, correlated significantly (r -0.73) with the decrease in MAP. Researchers found that a pre-anesthesia PVI value >15 successfully predicted a decrease in MAP of >25 mmHg with 79% sensitivity, 71% specificity, 73% positive predictive value, and 77% negative predictive value. According to researchers, PVI represents an "easy to perform, noninvasive, and inexpensive method for predicting patients who may develop severe hypotension."

PVI may show changes that reflect physiologic factors such as vascular tone, circulating blood volume, and intrathoracic pressure excursions. PVI is available as part of Masimo Rainbow SET Pulse CO-Oximetry--a breakthrough noninvasive monitoring platform capable of measuring multiple blood constituents that previously required invasive procedures, including: total hemoglobin (SpHb(R)), oxygen content (SpOC(TM)), carboxyhemoglobin (SpCO(R)), methemoglobin (SpMet(R)), PVI(R), and acoustic respiration rate (RRa(TM)), in addition to oxyhemoglobin (SpO2), pulse rate (PR), and perfusion index (PI).

(1) Tsuchiya, M., Yamada, T., and Asada, A. "Pleth Variability Index Predicts Hypotension During Anesthesia Induction." Acta Anaesthesiologica Scandinavica. May 2010, vol. 54, issue 5, pages 596-602. Available online here.

(2) This specific utility of PVI has not been reviewed by the US FDA.

About Masimo

Masimo (Nasdaq: MASI) develops innovative monitoring technologies that significantly improve patient care--helping solve "unsolvable" problems. In 1995, the company debuted Measure-Through Motion and Low Perfusion pulse oximetry, known as Masimo SET(R), which virtually eliminated false alarms and increased pulse oximetry's ability to detect life-threatening events. More than 100 independent and objective studies demonstrate Masimo SET provides the most reliable SpO2 and pulse rate measurements even under the most challenging clinical conditions, including patient motion and low peripheral perfusion. In 2005, Masimo introduced Masimo Rainbow SET(R) Pulse CO-Oximetry(TM), allowing noninvasive and continuous monitoring of blood constituents that previously required invasive procedures, including total hemoglobin (SpHb(R)), oxygen content (SpOC(TM)), carboxyhemoglobin (SpCO(R)), methemoglobin (SpMet(R)), and PVI(R), in addition to SpO2, pulse rate, and perfusion index (PI). In 2009, Masimo introduced Masimo Rainbow SET(R) Acoustic Monitoring(TM), the first-ever noninvasive and continuous monitoring of acoustic respiration rate (RRa(TM)). Masimo's Rainbow platform offers a breakthrough in patient safety by helping clinicians detect life-threatening conditions and helping guide treatment options. Founded in 1989, Masimo has the mission of "Improving Patient Outcomes and Reducing Cost of Care by Taking Noninvasive Monitoring to New Sites and Applications." Additional information about Masimo and its products may be found at

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 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 PVI will be useful in predicting anesthesia-induced hypotension in all surgical patients, and risks related to our belief that Masimo Rainbow SET Pulse CO-Oximetry noninvasive measurements (specifically SpHb, PVI, and SpO2) will provide sufficient sensitivity and specificity to help clinicians proactively monitor and manage hemoglobin, fluid and oxygen saturation levels more appropriately and conservatively for all patients, 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 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 forward-looking 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.

    Media Contacts:
    Dana Banks
    Masimo Corporation
    (949) 297-7348

Masimo, SET, Signal Extraction Technology, Improving Outcomes and Reducing Cost of Care by Taking Noninvasive Monitoring to New Sites and Applications, Rainbow, SpHb, SpOC, SpCO, SpMet, PVI, RRa, Radical-7, Rad-87, Rad-57,Rad-9, Rad-8, Rad-5,Pulse CO-Oximetry and Pulse CO-Oximeter are trademarks or registered trademarks of Masimo Corporation.

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