City Research Online

Abstract

The aim of the current work is to investigate the possibility of augmenting pulse oximetry algorithms to enable the estimation of venous parameters in peripheral tissues. In order to further understand the contribution of venous blood to the photoplethysmographic (PPG) signal, recordings were made from six healthy volunteer subjects during an exercise in which the right hand was placed in various positions above and below heart level. The left hand was kept at heart level as a control while the right hand was moved. A custom-made two-channel dual wavelength PPG instrumentation system was used to obtain the red and infrared plethysmographic signals from both the right and left index fingers simultaneously using identical sensors. Laser Doppler flowmetry signals were also recorded from an adjacent fingertip on the right hand. Analysis of all acquired PPG signals indicated changes in both ac and dc amplitude of the right hand when the position was changed, while those obtained from the left (control) hand remained relatively constant. Most clearly, in the change from heart level to 50cm below heart level there is a substantial decrease in both dc and ac amplitudes. This decrease in dc amplitude most likely corresponds to increased venous pooling, and hence increased absorption of light. It is speculated that the decrease in ac PPG amplitude is due to reduced arterial emptying during diastole due to increased downstream resistance due to venous pooling.

Publication Type:	Article
Additional Information:	Michelle Hickey ; Justin P. Phillips and Panayiotis Kyriacou " Venous pooling and drainage affects photoplethysmographic signals at different vertical hand positions ", Proc. SPIE 9332, Optical Diagnostics and Sensing XV: Toward Point-of-Care Diagnostics, 93320I . Copyright 2015 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. http://dx.doi.org/10.1117/12.2076732
Publisher Keywords:	Photoplethysmography, Pulse Oximetry, Venous, Arterial
Subjects:	R Medicine > RC Internal medicine T Technology > TK Electrical engineering. Electronics Nuclear engineering
Departments:	School of Science & Technology > Engineering

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