Comparison of Near-Infrared Spectroscopy and Reflectance Sensors to Traditional Pulse Oximetry Under Conditions of Low Blood Oxygen Saturation

摘要

Although the Navy has made substantial investments to mitigate risks associated with hypoxia, there are currently no means to monitor the physiological or cognitive status of aircrew in any military aircraft. One potential solution to this problem would be the deployment of a physiological monitoring and warning system. NAMRL investigators have completed two experiments comparing the performance of four oxygen saturation monitoring technologies: Near-infrared spectroscopy (NIRS), reflectance oximetry, and finger and ear pulse oximetry. In experiment one, a forehead-mounted reflectance oximeter was compared to a finger pulse oximeter during exposure to a simulated altitude of 18,000 feet. Results suggest that the forehead oximeter responds faster than the finger oximeter to sudden drops in blood oxygen saturation. Unfortunately the forehead-mounted oximeter was especially susceptible to dropped data points resulting from motion. In experiment two, subjects were equipped with a finger pulse oximeter, an ear pulse oximeter, and a forehead-mounted NIRS sensor during exposure to a simulated hypoxia profile including an altitude of 20,000 feet and a recovery phase. Subjects performed a cognitive test throughout the profile. Results showed that both the NIRS sensor and the ear oximeter responded significantly faster than the finger oximeter, although the ear oximeter returned dropped data points in the presence of motion. Conversely, the NIRS sensor provided continuous monitoring throughout the protocol and appeared more compatible with subjects. cognitive performance during recovery from hypoxia. Overall, the results imply that the NIRS system provides an accurate picture of the functional state of aircrew following a hypoxia event. NIRS's superior sensitivity and resistance to motion artifacts suggest it may be better suited than pulse oximetry for early detection of hypoxia in military aircraft. More work must be done to establish the validity of these findings.