New Study Evaluates the Utility of Masimo ORi™ in Reducing Hyperoxemia During Laparoscopic Gastrectomy

Neuchatel, Switzerland: Masimo (NASDAQ: MASI) today announced the findings of a prospective, double-blinded, randomized controlled study published in Medicine in which Dr. Jin Hee Ahn and colleagues at the Sungkyunkwan University School of Medicine in Seoul, Korea, evaluated the ability of Masimo ORi™ to assist clinicians in guiding supplemental oxygenation during elective laparoscopic gastrectomy surgery. The researchers found that the combination of ORi and standard of care oxygen saturation (SpO₂) monitoring reduced hyperoxemia compared to SpO₂ monitoring alone.¹

ORi, available outside the U.S. since 2014, is a noninvasive and continuous parameter intended to provide additional insight into a patient’s oxygen status under supplemental oxygen. Enabled by the multi-wavelength rainbow^® Pulse CO-Oximetry platform, ORi is provided alongside SpO₂ measured by clinically proven Masimo SET^® pulse oximetry.

Noting that the use of supplemental oxygen during general surgery increases the risk of hyperoxemia, the researchers sought to evaluate whether noninvasive, continuous ORi might improve clinicians’ ability to detect hyperoxemia, since SpO₂ monitoring alone cannot monitor beyond 100% saturation, and since arterial blood gas analysis has the disadvantages of being invasive and giving intermittent, delayed results. To test their hypothesis, the researchers randomly allocated 62 adult patients scheduled for elective laparoscopic gastrectomy into two groups, one whose fraction of inspired oxygen (FiO₂) during anesthesia was guided by ORi and SpO₂ monitoring (the ORi-SpO₂ group, n=30), and a control group whose FiO₂ was guided by SpO₂ monitoring alone (the SpO₂ group, n=32). Patients in both groups were monitored with Masimo Radical-7^® Pulse CO-Oximeters^® with rainbow^® sensors. In addition to Masimo ORi and SET^® SpO₂, Masimo PVi^® (pleth variability index) was monitored as part of goal-directed fluid management.
In the ORi-SpO₂ group, FiO₂ was adjusted to maintain ORi > 0 and < 0.3, which was evaluated every 2 to 3 minutes throughout surgery. In the SpO₂ group, FiO₂ was adjusted to maintain SpO₂ ≥ 98%, similarly evaluated every 2 to 3 minutes. To assess the incidence of hyperoxemia, the clinicians recorded the arterial partial pressure of oxygen (PaO₂), measured using an ABL-90 FLEX Plus blood gas analyzer, before surgical incision and one, two, and three hours after surgical incision. Hyperoxemia was defined as PaO₂ ≥ 100 mmHg and severe hyperoxemia as PaO₂ ≥ 200 mmHg.

The researchers found that one hour after surgical incision, PaO₂ was higher in the SpO₂ group (250.31 ± 57.39 mmHg) than in the ORi-SpO₂ group (170.07 ± 49.39 mmHg) (p < .001), and remained consistently higher in the SpO₂ group than in the ORi-SpO₂ group over time (p = .045). The rate of severe hyperoxemia was higher in the SpO₂ group (84.4%) than in the ORi-SpO₂ group (16.7%) 1 hour after incision (p < .001).
The researchers concluded, “[I]ntraoperative hyperoxemia was reduced when FiO₂ was adjusted based on the combination of SpO₂ and ORi compared with SpO₂ alone in patients undergoing laparoscopic gastrectomy.”
ORi has not yet received FDA clearance and is not available in the United States.