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Proceedings Paper

In-vivo studies of reflectance pulse oximeter sensor
Author(s): Jian Ling; Setsuo Takatani; George P. Noon; Yukihiko Nose
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Paper Abstract

Reflectance oximetry can offer an advantage of being applicable to any portion of the body. However, the major problem of reflectance oximetry is low pulsatile signal level which prevents prolonged clinical application during extreme situations, such as hypothermia and vasoconstriction. In order to improve the pulsatile signal level of reflectance pulse oximeter and thus its accuracy, three different sensors, with the separation distances (SPD) between light emitting diode (LED) and photodiode being 3, 5, and 7 mm respectively, were studied on nine healthy volunteers. With the increase of the SPD, it was found that both the red (660 nm) and near-infrared (830 nm) pulsatile to average signal ratio (AC/DC) increased, and the standard deviations of (AC/DC)red/(AC/DC)infrared ratio decreased, in spite of the decrease of the absolute signal level. Further clinical studies of 3 mm and 7 mm SPD sensors on seven patients also showed that the (AC/DC)red/(AC/DC)infrared ratio measured by the 7 mm sensor were less disturbed than the 3 mm sensor during the surgery. A theoretical study based on the three-dimensional photon diffusion theory supports the experimental and clinical results. As a conclusion, the 7 mm sensor has the highest signal-to- noise ratio among three different sensors. A new 7 mm SPD reflectance sensor, with the increased number of LEDs around the photodiode, was designed to increase the AC/DC ratio, as well as to increase the absolute signal level.

Paper Details

Date Published: 27 August 1993
PDF: 7 pages
Proc. SPIE 1887, Physiological Imaging, Spectroscopy, and Early-Detection Diagnostic Methods, (27 August 1993); doi: 10.1117/12.151190
Show Author Affiliations
Jian Ling, Baylor College of Medicine (United States)
Setsuo Takatani, Baylor College of Medicine (United States)
George P. Noon, Baylor College of Medicine (United States)
Yukihiko Nose, Baylor College of Medicine (United States)

Published in SPIE Proceedings Vol. 1887:
Physiological Imaging, Spectroscopy, and Early-Detection Diagnostic Methods
Randall Locke Barbour; Mark J. Carvlin, Editor(s)

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