New Study Suggests That Masimo SedLine® Brain Function Monitoring May Aid Early Identification of Patients at Risk of Developing Postoperative Delirium

Masimo (NASDAQ: MASI) today announced the findings of a prospective study published in Anesthesia & Analgesia in which Dr. Claudia Spies and colleagues investigated the relationship between parameters derived from electroencephalogram (EEG) spectra, measured using Masimo SedLine^® Brain Function Monitoring, and postoperative delirium (POD) in older patients undergoing elective surgery. The researchers found that the incidence of POD correlated with several spectral dynamics, in particular spectral edge frequency (SEF), suggesting that such EEG-based markers may help in early identification of patients at risk of developing POD.¹

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Masimo Root® with SedLine® Brain Function Monitoring (Photo: Business Wire)

POD is a frequent complication in geriatric patients, often associated with worse short- and long-term outcomes and long-term cognitive dysfunction. Noting that the incidence of POD is associated with prolonged EEG burst suppression during general anesthesia, the researchers sought to investigate whether specific preoperative, preexisting EEG signatures might be related to a higher risk of developing POD.

The investigators enrolled 237 patients ≥ 65 years scheduled for elective surgery of at least 60 minutes at the Charité-Universitätsmedizin Berlin (Campus Virchow Klinikum and Campus Mitte) between November 2014 and December 2016. Using Masimo Root^® with SedLine, frontal EEGs were recorded from before induction of anesthesia until return of consciousness. The researchers used the SedLine data to analyze a variety of EEG-derived parameters, including SEF (the frequency below which 95% of the power in the EEG is located), Patient State Index (a processed EEG parameter related to the effect of anesthetic agents), and duration of burst suppression, and also performed multitaper spectral analyses to calculate overall frontal power spectra across various frequency bands. Screening for POD was performed twice every day until the seventh day after surgery (or until hospital discharge) based on a variety of standard criteria, including the Nursing Delirium Screening Scale and Confusion Assessment Method. Patients with one or more positive screenings were classed as POD patients, and the remaining ones as NoPOD patients.

Of the 237 patients, 41 (17%) developed POD. The researchers found that two aspects of the preoperative EEG of POD patients was associated with lower values: SEF (POD group: 13.1 ± 4.6 Hz; NoPOD group: 17.4 ± 6.9 Hz; p = 0.002) and γ-band power (POD: -24.33 ± 2.8 dB; NoPOD: -17.9 ± 4.81 dB). Postinduction absolute α-band power was also significantly lower: POD: -7.37 ± 4.52 dB; NoPOD: -5 ± 5.03 dB. In POD patients, the ratio of preoperative to postinduction SEF was ~1; in NoPOD patients it was > 1, indicative of a slowing EEG with loss of consciousness. Finally, POD was independently associated with preoperative SEF (p = 0.025, odds ratios = 0.892, 95% CI 0.808 – 0.986), preoperative γ-band power (p = 0.029, OR = 0.568, 95% CI 0.342 – 0.944) and SEF ratio (p = 0.009, OR = 0.108, 95% CI (0.021 – 0.568).

The researchers concluded, “Lower preoperative SEF, absence of slowing in EEG while transitioning from preoperative state to unconscious state, and lower EEG power in relevant frequency bands in both these states are related to POD development. These findings may suggest an underlying pathophysiology and might be used as EEG-based marker for early identification of patients at risk to develop POD.”

The authors also noted, “Preoperative spectral EEG signatures and reduced EEG dynamics at loss of consciousness are associated with the development of POD in older patients, where changes in EEG signatures are most likely related to reduced GABA-ergic neuronal activation in POD patients. These findings can be described as predisposing EEG factors for POD, which might be used as a potential EEG-based marker for early identification of patients at risk to develop POD.”

David Drover, MD, Professor of Anesthesiology at Stanford Health Care, commented, “This study not only further supports existing knowledge but expands our understanding of how brain function monitoring can help clinicians improve postoperative outcomes in the elderly patient.”

Postoperative delirium is an acute state of mental confusion characterized by alterations in attention, consciousness, and disorganized thinking. A common and serious complication, POD afflicts up to 60% of patients after major surgery,^2-5 is most common in the elderly,^2-5 and occurs in up to 91% of the critically ill.⁶ POD is associated both with worse short- and long-term outcomes and higher costs,^3,6-9 and numerous medical bodies—including the American Society of Anesthesiologists (ASA), the United Kingdom National Institute for Health and Care Excellence, the American Geriatric Society, and the American College of Surgeons—have made the prevention of POD a public health priority.^10-13 The ASA’s Brain Health Initiative, dedicated to minimizing the impact of pre-existing cognitive deficits and optimizing the cognitive recovery and perioperative experience for adults 65 years and older undergoing surgery, describes POD as a “major public health issue.”¹⁴ The incidence of POD has been associated both with preoperative vulnerabilities and—of key importance to studies such as this—the cumulative duration of intraoperative EEG burst suppression. As numerous studies have found, processed EEG monitoring during surgery, by helping clinicians minimize the duration of burst suppression, may lower the rate of POD.^15-19

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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.²⁰ Masimo SET^® has also been shown to help clinicians reduce severe retinopathy of prematurity in neonates,²¹ improve CCHD screening in newborns,²² and, when used for continuous monitoring with Masimo Patient SafetyNet™ in post-surgical wards, reduce rapid response team activations, ICU transfers, and costs.^23-26 Masimo SET^® is estimated to be used on more than 200 million patients in leading hospitals and other healthcare settings around the world,²⁷ and is the primary pulse oximetry at 9 of the top 10 hospitals as ranked in the 2021-22 U.S. News and World Report Best Hospitals Honor Roll.²⁸ 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 Masimo Hospital Automation™ platform, and include Iris^® Gateway, iSirona™, Patient SafetyNet, Replica™, Halo ION™, UniView^®, UniView :60™, and Masimo SafetyNet™. 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. Koch S, Windmann V Chakravarty S, Kruppa J, Yürek F, Brown E, Winterer G, Spies C. Perioperative Electroencephalogram Spectral Dynamics Related to Postoperative Delirium in Older Patients. Anesth Analg. Dec 2021. 13(6):1598-1607. DOI: 10.1213/ANE.000000000000005668..
2. Lipowski ZL. Delirium in the elderly patient. N Engl J Med. (1989) 320:578–82. doi: 10.1056/NEJM198903023200907.
3. Khadka J, McAlinden C, Pesudovs K. Cognitive trajectories after postoperative delirium. N Engl J Med. (2012) 367:30–9. doi: 10.1056/NEJMoa1112923.
4. Inouye SK, Westendorp RG, Saczynski JS. Delirium in elderly people. Lancet. (2014) 383:911–22. doi: 10.1016/S0140-6736(13)60688-1.
5. Bin Abd Razak HR, Yung WY. Postoperative delirium in patients undergoing total joint arthroplasty: a systematic review. J Arthroplasty. (2015) 30:1414–7. doi: 10.1016/j.arth.2015.03.012.
6. Salluh JI, Wang H, Schneider EB, Nagaraja N, Yenokyan G, Damluji A, et al. Outcome of delirium in critically ill patients: systematic review and meta-analysis. BMJ. (2015) 350:h2538. doi: 10.1136/bmj.h2538.
7. Inouye SK. The dilemma of delirium: clinical and research controversies regarding diagnosis and evaluation of delirium in hospitalized elderly medical patients. Am J Med. (1994) 97:278–88. doi: 10.1016/0002-9343(94)90011-6.
8. Crocker E, Beggs T, Hassan A, Denault A, Lamarche Y, Bagshaw S, et al. Long-term effects of postoperative delirium in patients undergoing cardiac operation: a systematic review. Ann Thoracic Surg. (2016) 102:1391–9. doi: 10.1016/j.athoracsur.2016.04.071.
9. Mashour GA, Woodrum DT, Avidan MS. Neurological complications of surgery and anaesthesia. Br J Anaesthesia. (2015) 114:194–203. doi: 10.1093/bja/aeu296.
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11. Mohanty S, Rosenthal RA, Russell MM, Neuman MD, Ko CY, Esnaola NF. Optimal perioperative management of the geriatric patient: a best practices guideline from the American College of Surgeons NSQIP and the American Geriatrics Society. J Am College Surgeons. (2016) 222:930– 47. doi: 10.1016/j.jamcollsurg.2015.12.026.
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13. National Institute for Health and Care Excellence. Delirium in Adults. London: National Institute for Health and Care Excellence (2014).
14. Brain Health. ASA. https://www.asahq.org/in-the-spotlight/brain-health. Accessed 13 Nov 2021.
15. Tang CJ, Jin Z, Sands LP, Pleasants D, Tabatabai S, Hong Y, Leung JM. ADAPT-2: A Randomized Clinical Trial to Reduce Intraoperative EEG Suppression in Older Surgical Patients Undergoing Major Noncardiac Surgery. Anesth Analg 2020; 131(4):1228-1236.
16. Radtke FM, Franck M, Lendner J, Krüger S, Wernecke KD, Spies CD. Monitoring depth of anaesthesia in a randomized trial decreases the raten of postoperative delirium but not postoperative cognitive dysfunction. Br J Anaesthesia. (2013) 110:98–105. doi: 10.1093/bja/aet055.
17. MacKenzie KK, Britt-Spells AM, Sands LP, Leung JM. Processed electroencephalogram monitoring and postoperative delirium: a systematic review and meta-analysis. Anesthesiology. (2018)129:417–27. doi: 10.1097/ALN.0000000000002323.
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20. 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.
21. 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.
22. 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.
23. Taenzer A 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.
24. Taenzer A et al. Postoperative Monitoring – The Dartmouth Experience. Anesthesia Patient Safety Foundation Newsletter. Spring-Summer 2012.
25. McGrath S 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.
26. McGrath S et al. Inpatient Respiratory Arrest Associated With Sedative and Analgesic Medications: Impact of Continuous Monitoring on Patient Mortality and Severe Morbidity. J Patient Saf. 2020 14 Mar. DOI: 10.1097/PTS.0000000000000696.
27. Estimate: Masimo data on file.
28. 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 Root^® and SedLine^®. 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 Root and SedLine, contribute to positive clinical outcomes and patient safety; risks that the researchers’ conclusions and findings may be inaccurate; risks related to our belief that Masimo noninvasive medical breakthroughs provide cost-effective solutions and unique advantages; risks related to COVID-19; 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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