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Proceedings Paper

Higher temporal resolution is necessary for continuous-wave near -infrared spectrophotometric monitors in both cerebral and muscular tissue oximetry
Author(s): Eiichi Chihara; Toshikazu Shiga; Kazuhisa Tanabe; Yoshifumi Tanaka
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Paper Abstract

Conventional near infrared spectrophotometric monitors have temporal resolution of less than about 1 Hz. However, physiological Hb signals such as pulsation and muscle contraction have higher frequency than 1 Hz. Insufficient sampling rates inevitably lead aliasing of the recorded signals in tissue oximetry for both brain and muscle. Cerebral Hb signals (57 y.o. female artificially ventilated under general anesthesia) and thigh muscle (22 y.o. male with 20 W - 240 W exercise at 1 Hz cycling in semirecumbent ergometer) were measured with NIRS monitor with temporal resolution of 10 Hz (OMRON Co. Ltd., Japan). The detail of physiological fluctuations such as pulsation, ventilation, and muscle pumping was clearly recognized with a 10 Hz sampling. The comparison with recalculated waveforms at slower sampling rate (0.5 Hz, 1 Hz, 2 Hz) revealed that with slower sampling than 1 Hz cerebral respiratory waves were deformed by pulsation, and that magnitudes of muscle pumping could not be properly evaluated in dynamic exercise. In both pulsatile and muscle contractile cycle a phase delay between oxygenated component and deoxygenated one was also detected, which has been overlooked by conventional NIRS monitoring.

Paper Details

Date Published: 1 January 1998
PDF: 9 pages
Proc. SPIE 3194, Photon Propagation in Tissues III, (1 January 1998); doi: 10.1117/12.301038
Show Author Affiliations
Eiichi Chihara, Meiji Univ. of Oriental Medicine (Japan)
Toshikazu Shiga, Omron Institute of Life Science Co., Ltd. (Japan)
Kazuhisa Tanabe, Omron Institute of Life Science Co., Ltd. (Japan)
Yoshifumi Tanaka, Kyoto Prefectural Univ. of Medicine (Japan)

Published in SPIE Proceedings Vol. 3194:
Photon Propagation in Tissues III
David A. Benaron M.D.; Britton Chance; Marco Ferrari, Editor(s)

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