The recent study by van der Eijk and colleagues1 titled, "'New-Generation'" Pulse Oximeters in Extremely Low-Birth-Weight Infants: How Do They Perform in Clinical Practice?" evaluates the performance of pulse oximeters in the neonatal intensive care unit by comparing the variances in SpO2 values between 3 brands of pulse oximeters. We were not surprised that the study found little difference in performance between the 3 devices. As the manufacturer of one of the technologies evaluated in the study, we would like to offer some observations based on our experience collecting thousands of hours of pulse oximetry monitoring data in newborns. Almost all pulse oximeters perform adequately in well-perfused, stable patients. The differences between technologies are observed when monitoring during challenging conditions such as motion and low perfusion.
In 1997, Masimo received an FDA 510(k) with the indication for use to measure oxygen saturation "during both no motion and motion conditions." In 1999, Masimo received an FDA 510(k) adding the indication for use in "patients who are well or poorly perfused." Masimo received this indication by submitting test results showing that Masimo SET pulse oximetry could detect oxygen saturation changes during motion and low perfusion. Without measuring oxygen saturation during changing conditions, some pulse oximeters can appear to accurately measure oxygen saturation by freezing or by dynamic averaging. Both of these approaches mask the limitations of these pulse oximeters. In contrast, Masimo SET measure-through motion pulse oximeters work by actually separating the "noise" of venous blood and artifact from the arterial signal, providing more accurate measurements and fewer false alarms.
Many studies have shown that Masimo SET has superior performance compared with other pulse oximetry technologies during challenging conditions, including faster time to obtain reliable readings on start-up monitoring, fewer false alarms2,3 and data dropouts,4 and superior bradycardia detection.3,5 In several studies, Masimo SET has also been found to provide more accurate SpO2 values (when compared with blood gas values) than other commercially available oximeters.6-8 None of these performance characteristics were evaluated in the study by van der Eijk et al, but these factors are clinically meaningful at the bedside. How much variance there is between 2 devices monitoring a stable patient for a brief period of time when there is no gold standard comparison to validate the accuracy of either device, in our estimation, is of limited value in an evaluation of pulse oximetry technologies in these patients.
Improved outcomes are the true test of superiority of one technology over another, and Masimo SET pulse oximetry performance has been shown to translate into helping clinicians improve patient outcomes. In one study, retinopathy of prematurity was reduced by 58% in very low-birth-weight neonates at a center using Masimo SET whereas there was no significant decrease in retinopathy of prematurity at another center using the same protocol but with another pulse oximetry technology. When the center using the other pulse oximetry technology then switched to Masimo SET, a reduction in retinopathy of prematurity was observed.9 The measure-through motion and low-perfusion capabilities of Masimo SET also allow it to be used in previously unmonitored areas such as the general floor, where false alarms have plagued conventional pulse oximetry. A landmark study published in 2010 showed that clinicians using Masimo SET pulse oximeters on the general floor were able to decrease rapid response team activations, intensive care unit transfers, and intensive care unit days.10 A follow-up report to this study showed similar clinical outcomes on other floors implementing monitoring and no deaths or injuries due to opioid depression after more than 4 years.11
Finally, we agree with the authors that operator-related factors such as sensor placement are an important cause of aberrant pulse oximetry readings and applaud their cautions to use attention and care when placing sensors and setting device parameters. Even a technology as robust and reliable as pulse oximetry is subject to error or even failure when improperly used.
-Michael O'Reilly, MD, MS
Neonatal Guest Editor
Executive Vice President
Chief Medical Officer
Masimo Corporation
Irvine, California
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