FDA Clears Masimo’s O3 Regional Oximetry for Expanded Delta Hemoglobin Parameters

Masimo has earned U.S. Food and Drug Administration 510(k) clearance of expanded indications for the delta hemoglobin parameters provided with its O3 Regional Oximetry. The parameters—ΔcHb, ΔHHb, and ΔO2Hb—display relative hemoglobin changes that can help clinicians identify the underlying mechanisms responsible for changes in tissue oxygen saturation.

The clearance enables the hemoglobin parameters to be used in both cerebral and somatic applications as well as for all patient populations, including pediatric and neonatal patients.

O3, available on Masimo’s Root patient monitoring and connectivity platform, uses near-infrared spectroscopy (NIRS) to monitor and display continuous regional oxygen saturation values (rSO₂) in a specific tissue. rSO₂ reflects the balance between oxygen delivery and metabolic demands in the monitored organ. However, rSO₂ alone may not always indicate the reason for any imbalance. Delta hemoglobin parameters give clinicians the necessary insight to better understand the reasons for a patient’s changing rSO₂ by monitoring relative changes in the underlying components used to determine it: total hemoglobin (cHb), deoxygenated hemoglobin (HHb), and oxygenated hemoglobin (O2Hb). These additional data support a more informed clinical assessment of the appropriate intervention, ultimately helping drive patient care improvements.

Each of these parameters can provide valuable additional context for helping clinicians assess various physiological conditions. For example, venous congestion, a slowing or pooling of blood that has been associated with negative outcomes in numerous scenarios (i.e., reconstructive flaps failure), has been found to boost total hemoglobin (cHb) in tissue.¹

Using O3 delta hemoglobin parameters has also been successfully incorporated into clinical practice. In a randomized controlled trial published last year, Korean researchers explored how the use of the three parameters in their clinical practice could improve cerebral physiology maintenance, including cerebral blood flow and cerebral metabolic rate, in elderly patients undergoing surgery with general anesthesia.² Comparing the additional monitoring data and insight provided with O3 to traditional regional oximetry (i.e. relying on rSO₂ data alone), they found that adopting the more comprehensive approach—which included the delta hemoglobin parameters—“may be crucial for ensuring optimal management of cerebral physiology” in anesthetized elderly patients, “enhancing patient care and safety in this vulnerable population.”

These findings are in agreement with numerous publications, most notably, a 2022 article published in Anesthesia & Analgesia that highlighted the benefits of using these parameters in patients undergoing cardiac surgery.³ As Dr. Alexander Calderone and his colleagues noted, “[Traditional] [c]erebral oximeters are limited by their inability to reveal the exact cause of cerebral desaturation. … Anesthesiologists must, therefore, rely on complementary modalities to identify the etiology of desaturation.” In contrast, the researchers found the provision of the delta hemoglobin parameters with Masimo O3 helped to overcome these limitations. They determined that “[v]ariations in ΔHHb, ΔO2Hb, and ΔcHb can be used clinically to further characterize cerebral desaturation based on changes in cerebral metabolism and oxygen blood content, arterial cerebral blood flow, and venous congestion.”

O3 Regional Oximetry uses Masimo’s proprietary technology to provide both trending and absolute accuracy,* giving clinicians confidence that the numbers they see reflect actual current tissue oxygenation. With delta hemoglobin parameters now available for all applications and populations, O3 prioritizes insight into the physiology of each individual patient. With the combination of O3 and SedLine Brain Function Monitoring on Root, Masimo reportedly offers the only brain health solution on the market to provide comprehensive data about the bilateral brain on a single platform.

“Ensuring vital organs and tissues are receiving enough oxygen to meet their metabolic needs is the cornerstone of optimal anesthesia and critical care. Masimo SedLine provides a measure of brain activity and thus indirectly oxygen demand,” Masimo Senior Vice President of Global Clinical Affairs & Solutions Basil Matta, M.D., said. “O3 provides an indication of the balance between vital organ oxygen delivery, by tracking relative changes in oxygenated hemoglobin (O₂Hb), and demand, by tracking the changes in deoxygenated hemoglobin (HHb). By using SedLine and O3 together, the clinician can investigate why this balance may have changed, as indicated by concomitant changes in delta hemoglobin parameters and take advantage of this complementary information, as part of their overall clinical assessment, in initiating the appropriate intervention to restore the balance of oxygen delivery to demand baseline. Masimo Root with O3 and SedLine is a true Brain Health Platform and provides a truly multimodal view of the brain.”

Masimo develops and produces various monitoring technologies, including innovative measurements, sensors, patient monitors, and automation and connectivity solutions. Masimo SET Measure-through Motion and Low Perfusion pulse oximetry, introduced in 1995, has been shown to outperform other pulse oximetry technologies in more than 100 independent and objective studies. Masimo SET is estimated to be used on over 200 million patients annually worldwide and is the primary pulse oximetry at all 10 top U.S. hospitals as ranked in the 2025 Newsweek World’s Best Hospitals listing.

*O3 Regional Oximetry provides regional or tissue hemoglobin oxygen saturation with a trending specification of 3% ARMS (cerebral and somatic, all ages) and absolute accuracy specifications of 4% ARMS (cerebral, adults) and 5% ARMS (cerebral, pediatric patients and non-cerebral, adults). ARMS accuracy is a statistical calculation of the difference between device measurements and reference measurements. Approximately two-thirds of the device measurements fell within +/- ARMS of the reference measurements in a controlled study.

References
¹ Kagaya Y, Miyamoto S. A systematic review of near-infrared spectroscopy in flap monitoring: Current basic and clinical evidence and prospects. Int J Surg Reconstr. Oct 2017.  https://doi.org/10.1016/j.bjps.2017.10.020.
² Min JY, Kim JB, Jeon JP, Chung MY, Kim YH, Kim CJ. Assessing different brain oxygenation components in elderly patients under propofol or sevoflurane anesthesia: A randomized controlled study. J Clin Anesth. 12 June 2024. https://doi.org/10.1016/j.jclinane.2024.111519
³ Calderone A, Jarry S, Couture E, Brassard P, Beaubien-Souligny W, Momeni M, Liszkowski M, Lamarche Y, Shaaban-Ali M, Matta B, Rochon A, Lebon JS, Ayoub C, Martins MR, Courbe A, Deschamps A, Denault A. Early Detection and Correction of Cerebral Desaturation with Noninvasive Oxy-hemoglobin, Deoxy-hemoglobin, and Total Hemoglobin in Cardiac Surgery: A Case Series. Anesth Analg. December 2022 (135:6;1304-1314).