Masimo O3® Regional Oximetry and SedLine® Brain Function Monitoring Power Two Investigations into Postoperative Delirium Presented at IARS

May 1, 2018


Masimo (NASDAQ: MASI) announced today the use of Masimo technologies – O3® regional oximetry and SedLine® brain function monitoring – in two abstracts presented at the 2018 Annual Meeting of the International Anesthesia Research Society (IARS). Both studies investigated links between postoperative delirium and particular biomarkers.

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Masimo Root® Patient Monitoring and Connectivity Platform with SedLine® Brain Function Monitoring an ...

Masimo Root® Patient Monitoring and Connectivity Platform with SedLine® Brain Function Monitoring and O3® Regional Oximetry (Photo: Business Wire)

In the first study1, Dr. Aymen Benkreira and colleagues sought to identify a possible link between venous congestion from right ventricular failure and postoperative delirium after cardiac surgery. As a proxy for venous congestion, they investigated whether there was a link between portal vein pulsatility (evaluated by point-of-care Doppler ultrasound) and postoperative delirium and associated features. In addition to daily cognitive and delirium evaluations for five consecutive days, the patients were evaluated for asterixis and bilateral cerebral oximetry values using Masimo O3. Of the 145 adult patients enrolled in the study, an abnormal cognitive status was identified in 36.9% of assessments and portal vein pulsatility in 42.3% of assessments. The researchers found significant associations between portal pulsatility and:

  • the development of cognitive dysfunction (odds ratio of 2.10, confidence interval of 1.25-3.53, p=0.005)
  • the development of asterixis (OR of 2.23, CI of 1.13-4.41, p=0.02)
  • a more than 15% decrease in cerebral oximetry values from pre-operative baseline (OR of 2.23, CI of 1.12-4.71, p=0.02).

The researchers concluded, “This data presents for the first time an association between an objective sign of portal hypertension of cardiac origin and delirium in cardiac surgery patients. This suggests that delirium may have a congestive origin in some patients.”

In the second study2, Reine Ibala and colleagues sought to identify EEG biomarkers that could aid clinicians in preemptively identifying patients at risk for postoperative delirium. Such biomarkers – particular alpha and beta band oscillatory dynamics that may reflect the robustness of cortical circuits underlying cognitive processes – are commonly present in patients with clinically diagnosed cognitive impairment (dementia). The researchers theorized that there might be a link between dementia and postoperative delirium and thus also between postoperative delirium and cognitively normal patients whose EEG data exhibit similar biomarkers under anesthesia. They analyzed EEG data, collected using Masimo SedLine brain function monitoring, from 24 patients (21 cognitively normal, 3 with dementia). Analysis demonstrated a significant association between EEG point estimates for alpha/beta power and dementia (odds ratio of 1.43, 95% confidence interval of 1.14 to 1.79). Postoperative delirium for cognitively normal patients was associated with “visually evident decreased alpha/beta power,” passing the threshold of statistical significance.

The researchers concluded, “Decreased alpha/beta oscillation power during sevoflurane general anesthesia is strongly associated with known cognitive impairment. This dynamic may be used to develop principled neurophysiological-based approaches to aid the preemptive identification and care targeting of vulnerable patients. Cognitively normal patients who developed postoperative delirium demonstrated a similar neurophysiological profile – but to a lesser extent – compared to patients with dementia to suggest that postoperative delirium may be more closely associated with sub-clinical cognitive impairment than previously appreciated.”

SedLine brain function monitoring helps clinicians monitor the state of the brain under anesthesia with bilateral acquisition and processing of four leads of electroencephalogram (EEG) signals. Next Generation SedLine, recently released, features an enhanced signal processing engine, driving a variety of performance improvements, and an enhanced Multitaper Density Spectral Array (DSA). Next Generation SedLine can be used simultaneously with O3 regional oximetry on the Root® patient monitoring and connectivity platform for a more complete picture of the brain. O3 may help clinicians monitor cerebral oxygenation of adult and pediatric patients in situations in which pulse oximetry alone may not be fully indicative of the oxygen in the brain.

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  1. Benkreira A, Beaubien-Souligny W, Denault A, and Mailhot T. Postoperative delirium and hepatic venous congestion: a prospective study. Proceedings from the 2018 IARS Annual Meeting, Chicago, Illinois. #1470.
  2. Ibala R, Hahm, E, Maher S, Nebreda M, Garcia E, Nozari A, and Akeju O. Decreased EEG alpha/beta power during sevoflurane general anesthesia is associated with pre-existing cognitive impairment. Proceedings from the 2018 IARS Annual Meeting, Chicago, Illinois. #1173.

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. 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 help clinicians reduce severe retinopathy of prematurity in neonates,1 improve CCHD screening in newborns,2 and, when used for continuous monitoring with Masimo Patient SafetyNet™* 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,6 and is the primary pulse oximetry at 17 of the top 20 hospitals listed in the 2017-18 U.S. News and World Report Best Hospitals Honor Roll.7 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®), and more recently, Oxygen Reserve Index (ORi™), in addition to SpO2, pulse rate, and perfusion index (Pi). 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

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

*The use of the trademark Patient SafetyNet is under license from University HealthSystem Consortium.


  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;Jan 8;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. Estimate: Masimo data on file.

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 SedLine® and O3®. 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 SedLine and O3, 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 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, 949-396-3376