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Proceedings Paper

A modified algorithm for continuous wave near infrared spectroscopy applied to in-vivo animal experiments and on human skin
Author(s): John H. G. M. Klaessens; Jeroen C. W. Hopman; K. Djien Liem; Rowland de Roode; Rudolf M. Verdaasdonk; Johan M. Thijssen
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Paper Abstract

Continuous wave Near Infrared Spectroscopy is a well known non invasive technique for measuring changes in tissue oxygenation. Absorption changes (&Dgr;O2Hb and &Dgr;HHb) are calculated from the light attenuations using the modified Lambert Beer equation. Generally, the concentration changes are calculated relative to the concentration at a starting point in time (delta time method). It is also possible, under certain assumptions, to calculate the concentrations by subtracting the equations at different wavelengths (delta wavelength method). We derived a new algorithm and will show the possibilities and limitations. In the delta wavelength method, the assumption is that the oxygen independent attenuation term will be eliminated from the formula even if its value changes in time, we verified the results with the classical delta time method using extinction coefficients from different literature sources for the wavelengths 767nm, 850nm and 905nm. The different methods of calculating concentration changes were applied to the data collected from animal experiments. The animals (lambs) were in a stable normoxic condition; stepwise they were made hypoxic and thereafter they returned to normoxic condition. The two algorithms were also applied for measuring two dimensional blood oxygen saturation changes in human skin tissue. The different oxygen saturation levels were induced by alterations in the respiration and by temporary arm clamping. The new delta wavelength method yielded in a steady state measurement the same changes in oxy and deoxy hemoglobin as the classical delta time method. The advantage of the new method is the independence of eventual variation of the oxygen independent attenuations in time.

Paper Details

Date Published: 5 March 2008
PDF: 12 pages
Proc. SPIE 6848, Advanced Biomedical and Clinical Diagnostic Systems VI, 68480A (5 March 2008); doi: 10.1117/12.763830
Show Author Affiliations
John H. G. M. Klaessens, Univ. Medical Ctr. Utrecht (Netherlands)
Jeroen C. W. Hopman, Radboud Univ. Nijmegen Medical Ctr. (Netherlands)
K. Djien Liem, Radboud Univ. Nijmegen Medical Ctr. (Netherlands)
Rowland de Roode, Univ. Medical Ctr. Utrecht (Netherlands)
Rudolf M. Verdaasdonk, Univ. Medical Ctr. Utrecht (Netherlands)
Johan M. Thijssen, Radboud Univ. Nijmegen Medical Ctr. (Netherlands)

Published in SPIE Proceedings Vol. 6848:
Advanced Biomedical and Clinical Diagnostic Systems VI
Tuan Vo-Dinh; Warren S. Grundfest; David A. Benaron; Gerald E. Cohn, Editor(s)

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