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Proceedings Paper

Measurement of blood hematocrit by dual-wavelength near-IR photoplethysmography
Author(s): Joseph M. Schmitt; Guan-Xiong Zhou; Justin Miller
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Paper Abstract

Blood hematocrit is routinely determined in the clinic by analysis of blood samples. This paper introduces an non-invasive method for measuring arterial blood hematocrit which, when combined with pulse oximetry, potentially enables simultaneous monitoring of hemoglobin concentration and oxygen saturation. It is based on the same principles underlying pulse oximetry, except two light sources that emit close to isobestic wavelengths of oxy/deoxyhemoglobin in the near-infrared band (800 nm and 1300 nm) are employed. Hematocrjt is related to the ratios of the pulsatile and nonpulsatile components of the diffuse intensity transmitted through a blood-perfused tissue at these wavelengths. To test the feasibility of the method, we developed an in vitro light-scattering model with optical properties similar to those of skin tissue. Measurements were made using semiconductor light sources and detectors. We discuss the experimental results in the context of theoretical predictions that show the effect of variations in the volume fraction of blood and water in tissue. Finally, potential problems concerning calibration in a clinical setting are addressed.

Paper Details

Date Published: 6 May 1992
PDF: 12 pages
Proc. SPIE 1641, Physiological Monitoring and Early Detection Diagnostic Methods, (6 May 1992); doi: 10.1117/12.59360
Show Author Affiliations
Joseph M. Schmitt, National Institutes of Health (United States)
Guan-Xiong Zhou, National Institutes of Health (United States)
Justin Miller, National Institutes of Health (United States)

Published in SPIE Proceedings Vol. 1641:
Physiological Monitoring and Early Detection Diagnostic Methods
Thomas S. Mang, Editor(s)

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