Validation of EGOS-600 Near Infrared Spectroscopy to Measure Cerebral Oxygen Saturation by Comparing to NIRO-200nx In Vitro and In Vivo

Abstract

Introduction: Near-infrared spectroscopy (NIRS) has been increasingly used to monitor cerebral oxygen saturation (ScO2) during cardiac surgery and intensive care. NIRO200-nx (Hamamatsu Phototonics, Japan) is one of widely used NIRS devices in the world. EGOS6500 is a new device produced by Qinghua University, China that is considerably less costly. We validated EGOS6500 by comparing toNIRO200-nxto measure ScO2in laboratory and clinical settings. Methods: Laboratory test A liquid tissue model was made consisting of 40 ml of human whole blood, 25 ml intralipid 20%and 935 ml buffer solution. SO2levels ranging 20-80%were made by adding oxygen or an inorganic reducer. Eight pairs of measures were obtained. Clinical test. We enrolled 31 children (age 0.7-61m, median 11m) and 31 adults(59 +/- 12y) within one week after cardiac surgery. One probe of each device was sequentially placed at the left or right side of patient's forehead to measure ScO2 at 2-3 hourintervals. 100 pairs of ScO2 were obtained in each group. Bland and Altman method was used for data analysis. Results: Laboratory test showed a trend ofoverestimating SO2 by EGOS6500 when average SO2 > 40% and underestimating when < 40%. This trend did not appear in patients. The bias was-5.9 in children and -4.1% in adults. The limits of agreements were 1.3 to -13.1% in children, and 3.3 to -11.5% in adults. Conclusions: EGOS6500 introduces a small underestimation of ScO2 when compared to NIRO200-nx, with acceptable limits of agreements. EGOS6500, with its considerably low cost, is clearly appealing in Asian countries.