Affiliations: Department of Pediatrics, University of British Columbia, Vancouver, Canada
Note: [] Corresponding author: Prof. Andrew Macnab, Director, Critical Care Research Office, Room L317, Mail Box 80, Children's & Women's Health Centre, 4480 Oak St., Vancouver, BC, Canada V6H 3V4. Tel.: +1 (604) 875 3524; Fax: +1 (604) 875 2890; E-mail: [email protected].
Abstract: We used a living biological phantom to evaluate whether previously observed clinical differences in data collection between two similar near infrared spectrophotometers were due to technical design differences. A Somanetics INVOS-5100 was compared to a Hamamatsu NIRO-300. Both express the ratio of oxygenated hemoglobin to total hemoglobin concentration as a percentage, and both are intended for monitoring cerebral oxygenation status at the bedside. The living phantom simulated different bone densities and contained a low haematocrit solution of blood, intra-lipid, and saline, to which was added grower's yeast to alter oxygenation status. Results: In all trials, oxygen saturation decreased from 100% to 0% as the yeast consumed the available oxygen. In all trials the spectrometers were significantly correlated (range: r2=0.815 to 0.995, p<0.05 for r2>0.232). The NIRO-300 indicated oxygenation change 1 minute after addition of yeast, whereas the INVOS-5100 showed change after 5 minutes. Simulated bone thickness had almost no effect upon the NIRO-300, but did affect the INVOS-5100. Conclusion: In this study, the spectrophotometers had similar results consistent with the technical design differences: the INVOS-5100 does not report hemoglobin saturation change above 95% or below 15% while the NIRO-300 reports the full range from 100% to 0%.
Journal: Spectroscopy, vol. 19, no. 3, pp. 165-169, 2005
