View all news

Masimo Announces Recent Study Monitoring Methemoglobin Levels During Administration of Inhaled Nitric Oxide


IRVINE, Calif.--(BUSINESS WIRE)--Feb. 21, 2017-- Masimo (NASDAQ: MASI) announced today the findings of a recent study conducted on children admitted to a Ugandan hospital with fever and malaria, in which Masimo’s noninvasive measurement SpMet® was used to monitor methemoglobin (MetHb) levels. One group of children with severe malaria was selected to receive inhaled nitric oxide (iNO) treatment as an adjunct to intravenous therapy while a placebo group received room air. Both of these groups were monitored with SpMet.1

Red blood cells containing hemoglobin can become oxidized in the presence of certain drugs and compounds, including nitric oxide, changing it to methemoglobin (MetHb), which impairs the oxygen-carrying capacity of blood. When MetHb levels rise, headache, respiratory distress, cyanosis, and finally death may occur. A 2004 study conducted at Johns Hopkins Hospital reported that 20% of the patients tested, from neonates to geriatrics, had elevated MetHB caused by the side effects of 40 drugs given to patients in hospitals, including nitric oxide. Three patients nearly died and one patient died from elevated MetHb during the study period.2

An estimated 1.2 million people die from malaria annually worldwide, with a mortality rate of 8-20% in children with severe malaria.3 In the Ugandan study, Dr. Andrea Conroy and colleagues at Jinja Regional Referral Hospital assessed an adjunctive therapy for malarial patients: the administration of inhaled nitric oxide (iNO) – but as iNO is absorbed by the body, it “induces MetHb in a dose-dependent manner.” Noting that “[t]here are no reliable estimates of methemoglobinemia in low resource clinical settings,” but seeking to “evaluate whether iNO could improve clinical recovery…in a cohort of children with severe malaria,” the investigators chose to monitor MetHb levels during treatment with a Masimo Rad-57® Pulse CO-Oximeter® with noninvasive SpMet monitoring.

The investigators in Uganda selected 180 children admitted to the hospital with severe malaria between 2011 and 2013 to receive either iNO (n=88) or a placebo, room air (n=92), in conjunction with standard anti-malarial treatment. MetHb levels were measured on a four-hourly basis following gas initiation, using Masimo SpMet. Between gas initiation and the first check with SpMet, MetHb levels rose from an average of 1.8% to 4.1% for the iNO group but stayed the same (1.7% to 1.8%) in the placebo group. MetHb levels typically plateaued within 12-24 hours of receiving iNO. Gas was withdrawn for 31 children (placebo: 12; iNO: 19; p=0.13).

The researchers stated that “we were able to evaluate the variability in MetHb responses within subjects and the frequency of methemoglobinemia prompting study gas discontinuation. Despite the high doses of iNO administered, study gas was temporarily discontinued only five times for MetHb >10% (all children in the iNO group). We were able to re-start study gas for all children that had a MHb measurement that exceeded 10% once the MetHb returned to <7 % without having the MetHb exceed 10% again. It was not necessary to wean children off iNO, in contrast to studies administering iNO to neonates with hypoxic respiratory failure, as we did not observe any rebound effects (e.g. worsening oxygenation) following discontinuation of study gas.”

The authors concluded that, “Hospitalized children with evidence of impaired oxygen delivery, metabolic acidosis, anemia, or malaria were at risk of methemoglobinemia. However, we demonstrated high-dose iNO could be safely administered to critically ill children with severe malaria with appropriate MHb monitoring.”

Joe Kiani, Founder and CEO of Masimo, stated, “It’s great to see that our invention of continuous methemoglobin monitoring has allowed these clinicians to study the outcomes of administering iNO treatment. We hope to continue developing monitoring technologies that help to address such public health crises.”

SpMet monitoring is not intended to be used as the sole basis for making diagnosis or treatment decisions. It is intended to be used in conjunction with other clinical tools, including signs and symptoms and laboratory blood tests.

@MasimoInnovates | #Masimo


  1. Conroy et al. Methemoglobin and nitric oxide therapy in Ugandan children hospitalized for febrile illness: results from a prospective cohort study and randomized double-blind placebo-controlled trial. BMC Pediatrics. (2016) 16:177. DOI 10.1186/s12887-016-0719-2.
  2. Ash-Bernal et al. Acquired methemoglobinemia: A retrospective series of 138 cases at 2 teaching hospitals. Medicine. October 2004;83(5)265-73. DOI 10.1097/
  3. Murray et al. Global malaria mortality between 1980 and 2010: a systematic analysis. Lancet. 2012;379(9814):413-31.

About Masimo

Masimo (NASDAQ: MASI) is a global leader in innovative noninvasive monitoring technologies. Our mission is to improve patient outcomes and reduce the cost of care by taking noninvasive monitoring to new sites and applications. In 1995, the company debuted Masimo SET® Measure-through Motion and Low Perfusion™ pulse oximetry, which has been shown in multiple studies to significantly reduce false alarms and accurately monitor for true alarms. Masimo SET® has also been shown to helps clinicians reduce severe retinopathy of prematurity in neonates,1 improve CCHD screening in newborns,2 and, when used for continuous monitoring in post-surgical wards, reduce rapid response activations and costs.3,4,5 Masimo SET® is estimated to be used on more than 100 million patients in leading hospitals and other healthcare settings around the world. 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®), and more recently, Pleth Variability Index (PVi®) and Oxygen Reserve Index (ORi™), in addition to SpO2, pulse rate, and perfusion index (PI). Studies with SpHb have shown reductions in unnecessary blood transfusion*,6,7 and when used with PVi, reductions in length of hospital stay8 and 30- and 90-day mortality.9 In 2014, Masimo introduced Root®, an intuitive patient monitoring and connectivity platform with the Masimo Open Connect™ (MOC-9™) interface, enabling other companies to augment Root with new features and measurement capabilities. Masimo is also taking an active leadership role in mHealth with products such as the Radius-7™ wearable patient monitor, iSpO2® pulse oximeter for smartphones, and the MightySat™ fingertip pulse oximeter. Additional information about Masimo and its products may be found at Published clinical studies on Masimo products can be found at

*Clinical decisions regarding red blood cell transfusions should be based on the clinician’s judgment considering, among other factors: patient condition, continuous SpHb monitoring, and laboratory diagnostic tests using blood samples.


  1. 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.
  2. 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;338.
  3. 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.
  4. Taenzer AH et al. Postoperative Monitoring – The Dartmouth Experience. Anesthesia Patient Safety Foundation Newsletter. Spring-Summer 2012.
  5. 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.
  6. Ehrenfeld JM et al. Continuous Non-invasive Hemoglobin Monitoring during Orthopedia Surgery: A Randomized Trial. J Blood Disorders Transf. 2014. 5:9. 2.
  7. Awada WN et al. Continuous and noninvasive hemoglobin monitoring reduces red blood cell transfusion during neurosurgery: a prospective cohort study. J Clin Monit Comput. 2015 Feb 4.
  8. Thiele RH et al. Standardization of Care: Impact of an Enhanced Recovery Protocol on Length of Stay, Complications, and Direct Costs after Colorectal Surgery. JACS (2015). doi: 10.1016/j.jamcollsurg.2014.12.042.
  9. Nathan N et al. Impact of Continuous Perioperative SpHb Monitoring. Proceedings from the 2016 ASA Annual Meeting, Chicago. Abstract #A1103.

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 SpMet®. 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 SpMet, contribute to positive clinical outcomes and patient safety; 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 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.

Source: Masimo

Evan Lamb

Multimedia Files:

Categories: Press Releases
View all news