Khanokh, B.

Nitzan, M.

English

Электронная библиотека БГУ

THE PHOTOPLETHYSMOGRAPHY (PPG) APPARATUS FOR 
DIAGNOSIS OF THE PERIPHERAL BLOOD CIRCULATION
B. Khanokh, M. Nitzan
Department of Applied Physics/Electro-Optics Jerusalem College Technology
The modern photoplethysmography (PPG) uses the achievements of 
quantum electronics. The PPG measures the cardiac induced changes in 
tissue blood volume by light transmission measurements.The transmission 
PPG probe consisted of a light emitting diode (LED) and a PIN 
photodetector which were attached to the palmar and dorsal aspects of the 
index fingers bilaterally. The light from the LED was modulated at a 
frequency of 3kHz and the detected transmitted light was filtered through a 
narrow band around 3kHz to avoid background light. The signal from the 
detector was then demodulated in order to obtain the PPG signal. The PPG 
signals were sampled at a rate of 500 samples per sec and digitally stored 
for further processing.
After the examination, the stored data was digitally analyzed for the 
detection of the minimum and maximum of each PPG pulse. For each PPG 
pulse, the baseline BL of the pulse and its amplitude AM were determined. 
In this study, only the very low frequency (VLF) spontaneous fluctuations 
were investigated. The low frequency (LF) fluctuations were filtered out 
by the smoothing method of moving average and were removed (trend 
removal) by fitting a fifth order polynomial to the data and subtracting it 
from the original curve.
Another parameter derived from AM and BL was examined: the 
statistical parameter STD/AVR of ratio AM/BL. The very low frequency 
(VLF) fluctuations in BL and AM showed high correlation between the 
right and left hands and foots. Good correlation was also found between 
the hand and the foot. The right-left coefficient of correlation was little 
dependent of the subject's age; the coefficient of correlation between AM 
and BL and STD/AVG(AM/BL) decreased with age.
The high correlation between the VLF fluctuations of the PPG 
parameters in different body sites show that their origin is central. The 
similarity in the spontaneous fluctuations of the PPG signal and heart rate 
indicates that both are mediated by the autonomic nervous system. The 
VLF fluctuations of the PPG parameters and the correlation coefficients 
between them enable the understanding and the assessment of the 
autonomic nervous system function.
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The photoplethysmography (PPG) apparatus for diagnosis of the peripheral blood circulation

http://elib.bsu.by/bitstream/123456789/32645/1/26.pdf

The photoplethysmography (PPG) apparatus for diagnosis of the peripheral blood circulation

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