PMID: 8459696Mar 1, 1993Paper

Quantitative photoplethysmography: Lambert-Beer law or inverse function incorporating light scatter

Journal of Biomedical Engineering
M CejnarS N Hunyor

Abstract

Finger blood volume is commonly determined from measurement of infra-red (IR) light transmittance using the Lambert-Beer law of light absorption derived for use in non-scattering media, even when such transmission involves light scatter around the phalangeal bone. Simultaneous IR transmittance and finger volume were measured over the full dynamic range of vascular volumes in seven subjects and outcomes compared with data fitted according to the Lambert-Beer exponential function and an inverse function derived for light attenuation by scattering materials. Curves were fitted by the least-squares method and goodness of fit was compared using standard errors of estimate (SEE). The inverse function gave a better data fit in six of the subjects: mean SEE 1.9 (SD 0.7, range 0.7-2.8) and 4.6 (2.2, 2.0-8.0) respectively (p < 0.02, paired t-test). Thus, when relating IR transmittance to blood volume, as occurs in the finger during measurements of arterial compliance, an inverse function derived from a model of light attenuation by scattering media gives more accurate results than the traditional exponential fit.

References

Apr 1, 1988·Journal of Biomedical Engineering·K YamakoshiC Murphy

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Citations

Apr 16, 1998·Medical & Biological Engineering & Computing·J PenazP Jurak
Apr 1, 1995·Acta Anaesthesiologica Scandinavica·L G LindbergM Vegfors
Sep 22, 2015·IEEE Transactions on Bio-medical Engineering·Yu Sun, Nitish Thakor
Jul 19, 2013·Journal of Medical Engineering & Technology·Jong Yong Abdiel FooXin Ji Alan Tan
Dec 24, 2008·Physiological Measurement·Maria GuerrisiNicola Toschi
Jul 12, 2020·Epilepsia·Fatemeh Mohammadpour TouserkaniTobias Loddenkemper
Jan 10, 2020·Computational and Mathematical Methods in Medicine·Guangda LiuShang Zhang

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