Comparison of the Effects of Motion and Environment Conditions on Accuracy of Handheld and Finger-Based Pulse Oximeters

Introduction: The most common cause of preventable death on the battlefield is significant blood loss, eventually causing decrease in tissue oxygen delivery. Pulse oximeters (POs) are widely used by the Israeli Defense Forces to obtain fast and noninvasive information about peripheral oxygen saturation (SpO2). However, POs are produced by different manufacturers and therefore include different sensors and are based on distinctive algorithms. This makes them susceptible to different errors caused by factors varying from environmental conditions to the severity of injury. The objectives of this study were to compare the reliability of different devices and their accuracy under various conditions. Material and Methods: Six POs underwent performance analysis. The finger-based category included: MightySat by Masimo, Onyx II by Nonin, and CMS50D by Contec. The handheld category comprised: RAD5 by Masimo, 9847 model by Nonin, and 3301 model by BCI. Several environmental and physiological parameters were altered using the ProSim8 simulator by Fluke biomedical, forming unique test cases under which the devices were tested in stationary and motion conditions. Results: All finger-based POs showed higher error rates of PO SpO2 and heart rate measurements in motion conditions, regardless of the manufacturer. However, newer devices in the handheld category were not affected. Results presented in Phase II showed that the SpO2 measurement error in all the devices was affected by pigmentation. However, the CMS50D, considered a low-cost device, had a significantly higher error size than other devices. In the devices that were influenced both by pigmentation and the finger cleanliness factors, the combined detected error size was clinically significant. The pigmentation, ambient light, and finger cleanliness also had a significant effect on the heart rate measurement in the CMS50D model, unlike the handheld devices, which were not affected. During Phase II, neither the Nonin nor the Masimo devices were deemed to have a significant advantage. Conclusion: Considering measurement limitations of POs used is extremely important. Use of handheld devices should be favored for use in motion conditions. Technologically advanced and/or recently developed devices should be preferred because of evolving algorithms, which decrease or eliminate the error factors. The "dirty finger"effect on the measurement error cannot be neglected and therefore the action of finger cleaning should be considered part of the treatment protocol.