New Peer-Reviewed Clinical Study Concludes that Masimo Rainbow SET Technology is Accurate in Noninvasively Detecting Both Carbon Monoxide and Methemoglobin Poisoning

January 9, 2007
Irvine, California January 9, 2007 - Masimo, the inventor of Pulse CO-Oximetry and Read-Through Motion and Low Perfusion pulse oximetry, reported that results of a human volunteer study published in the peer-reviewed journal, Anesthesiology, concluded Masimo Rainbow SET technology accurately and reliably detects both carbon monoxide and methemoglobin poisoning. The study's authors said that the accuracy of this technology in measuring methemoglobin "is approximately the same as the specified uncertainty of the (invasive) laboratory CO-oximeters," adding that Masimo Rainbow SET technology "represents a significant improvement in our oxygenation monitoring capability."1

The new study was led by Steven J. Barker, PhD, MD, who is the Chair of the Department of Anesthesiology at the University of Arizona and has recently joined Masimo's Board of Directors. Ten volunteers breathed 500 ppm carbon monoxide until their carboxyhemoglobin (hemoglobin contaminated by carbon monoxide) levels reached 15%, and ten different volunteers received 300 mg of intravenous sodium nitrite to induce methemoglobin, a dysfunctional form of hemoglobin that starves tissues of oxygen. All subjects were instrumented with arterial cannulas and six Masimo Rainbow SET-enabled monitoring devices. Arterial blood was analyzed by three laboratory CO-Oximeters, and the resulting carboxyhemoglobin and methemoglobin measurements were compared with the corresponding pulse oximeter readings. The results showed the Masimo Rainbow SET technology measured carboxyhemoglobin with an uncertainty of ?2% within the range of 0-15%, and it measured methemoglobin with an uncertainty of ?0.5% within the range of 0-12%.

The University of Arizona researchers concluded that Masimo Rainbow SET technology "seems to be a major advance in pulse oximetry. It is the first commercially produced pulse oximeter to use multiple wavelengths of light, and we have found it to be capable of detecting and measuring both methemoglobin and carboxyhemoglobin."

The Arizona study reinforces clinical studies presented at last month's American Association of Respiratory Care (AARC) Congress in Las Vegas. Studies released at the AARC highlighted the significant clinical benefits to be gained by noninvasively screening patients for carbon monoxide poisoning using the "rapid," "inexpensive" and "reliable" Masimo Rainbow SET Pulse CO-Oximetry technology.

In one study released at the AARC, which included more than 5,000 patients, a research team led by Dr. Robert Partridge and Dr. Gregory Jay of Rhode Island Hospital at Brown University Medical School concluded that the use of Masimo Rainbow SET as a noninvasive test for carbon monoxide toxicity (COT) can effectively and efficiently be performed at ED triage, and that "unsuspected COT may be identified using noninvasive COHb screening and the prevalence of COT may be higher than previously recognized."2

Additionally, a group of researchers at the Erlanger Health System in Chattanooga, TN used the Masimo Rainbow SET technology to assess CO levels on 136 patients who presented to the outpatient pulmonary lab for arterial blood gas (ABG) draws to evaluate patient's smoking history as well as 21 patients who presented with burns and inhalation injuries in the ED who also received ABGs.?They concluded that the technology was "quite reliable at detecting elevated CO levels in patients presenting to the pulmonary lab or emergency department."3
?BR>About Masimo
Masimo develops innovative monitoring technologies that significantly improve patient care-helping solve "unsolvable" problems. In 1995, the company debuted Read-Through Motion and Low Perfusion pulse oximetry, known as SET, and with it virtually eliminated false alarms and increased pulse oximetry's ability to detect life-threatening events. More than 100 independent clinical studies have confirmed that Masimo SET technology allows clinicians to accurately monitor blood oxygen saturation in critical care situations-establishing the technology as the "gold standard" pulse oximetry and substantially contributing to improved patient outcomes. In 2005 Masimo introduced Masimo Rainbow SET Pulse CO-Oximetry, which, for the first time, noninvasively monitors the level of carbon monoxide and methemoglobin in the blood, allowing early detection and treatment of potentially life-threatening conditions. Masimo, founded in 1989, has the mission of "Improving Patient Outcome 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

Tom McCall
Masimo Corporation

1 Measurement of Carboxyhemoglobin and Methemoglobin by Pulse Oximetry, A Human Volunteer Study: Steven J. Barker, Ph.D., M.D., Jeremy Curry, M.D., Daniel Redford, M.D., Scott Morgan, B.S.: Anesthesiology 2006; 105:1-1

2 Non-Invasive Carboxyhemoglobin Monitoring: Screening Emergency Department Patients for Carbon Monoxide Exposure.?Partridge R, Chee KJ, Suner S, Sucov A, Jay G.?Department of Emergency Medicine, Rhode Island Hospital, Brown Medical School, Providence, RI.

3 Evaluation of a New Pulse CO-Oximeter: Noninvasive Measurement of Carboxyhemoglobin in the Outpatient Pulmonary Lab and Emergency Departments.?Layne T, Snyder C, Brooks D, Enjeti.?Pulmonary Physiology Department, Erlanger Health System, Chattanooga, TN.

Masimo, SET, Signal Extraction Technology, Radical, Radical-7, Rad57, APOD, and Improving and Reducing Cost of Care by Taking Noninvasive Monitoring to New Sites and Applications are registered trademarks of Masimo Corp. Rainbow, SpCO, SpMet and Pulse CO-Oximeter are trademarks of Masimo Corp.