In this article we investigate the presence of gastric motility (GM) oscillation in the lower frequency range of photoplethysmography (PPG) signal. The objective of this article is to analyze the lower frequency oscillations of PPG signal using the novel autoregressive (AR) model and studying the presence of gastric motility (GM) rhythm in finger PPG. We acquired finger PPG and GM (measured using Electrogastrogram, EGG) signals at the sampling rate of 100 Hz simultaneously from 10 healthy subjects for 30 minutes duration in fasting and postprandial states. A lower frequency oscillation (≈ 0.05 Hz) called slow wave was extracted from PPG signal which looks similar to the slow wave of GM in both shape and frequency in the range (0 - 0.1953) Hz using discrete wavelet transform (DWT). In a previous study, we demonstrated that there is a good cross-correlation exists between slow waves on both PPG and EGG signals [Annals of Biomedical Engg. DOI: 10.1007/s10439-010-0113-4]. Here in this study, power spectral density (PSD) of PPG and EGG slow waves were estimated using AR spectral estimation method. Dominant frequencies of PPG and EGG slow wave were estimated and the results imply that finger PPG signal reveals GM related information. ©2010 IEEE.

Manivannan Muniyandi

Department of Applied Mechanics

V. Srinivasa Chakravarthy

AR MODELS

component

DISCRETE WAVELETS

ELECTROGASTROGRAPHY

GASTRIC MOTILITY

Discrete wavelet transforms

Electrophysiology

power spectral density

Spectrum Analysis

Argon

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Measurement of gastric oscillations from finger photoplethysmographic signal using autoregressive model

2010 IEEE International Conference on Communication Control and Computing Technologies, ICCCCT 2010

This article investigates the possibility of extracting gastric motility (GM) information from finger photoplethysmographic (PPG) signals non-invasively. Now-a-days measuring GM is a challenging task because of invasive and complicated clinical procedures involved. It is well-known that the PPG signal acquired from finger consists of information related to heart rate and respiratory rate. This thread is taken further and effort has been put here to find whether it is possible to extract GM information from finger PPG in an easier way and without discomfort to the patients. Finger PPG and GM (measured using Electrogastrogram, EGG) signals were acquired simultaneously at the rate of 100 Hz from eight healthy subjects for 30 min duration in fasting and postprandial states. In this study, we process the finger PPG signal and extract a slow wave that is analogous to actual EGG signal. To this end, we chose two advanced signal processing approaches: first, we perform discrete wavelet transform (DWT) to separate the different components, since PPG and EGG signals are non-stationary in nature. Second, in the frequency domain, we perform cross-spectral and coherence analysis using autoregressive (AR) spectral estimation method in order to compare the spectral details of recorded PPG and EGG signals. In DWT, a lower frequency oscillation (≈0.05 Hz) called slow wave was extracted from PPG signal which looks similar to the slow wave of GM in both shape and frequency in the range (0-0.1953) Hz. Comparison of these two slow wave signals was done by normalized cross-correlation technique. Cross-correlation values are found to be high (range 0.68-0.82, SD 0.12, R = 1.0 indicates exact agreement, p<0.05) for all subjects and there is no significant difference in cross-correlation between fasting and postprandial states. The coherence analysis results demonstrate that a moderate coherence (range 0.5-0.7, SD 0.13, p<0.05) exists between EGG and PPG signal in the ''slow wave'' frequency band, without any significant change in the level of coherence in postprandial state. These results indicate that finger PPG signal contains GM-related information. The findings are sufficiently encouraging to motivate further exploration of finger PPG as a non-invasive source of GM-related information. © 2010 Biomedical Engineering Society.

Annals of Biomedical Engineering

On non-invasive measurement of gastric motility from finger photoplethysmographic signal

IEEE Transactions on Biomedical Engineering

Wavelet analysis of oscillations in the peripheral blood circulation measured by laser Doppler technique

Journal of the Neurological Sciences

Stomach distension increases efferent muscle sympathetic nerve activity and blood pressure in healthy humans

Physiological Measurement

The variability of the photoplethysmographic signal - a potential method for the evaluation of the autonomic nervous system

Proceedings of the IEEE

Spectrum analysis—A modern perspective

Journal	2010 IEEE International Conference on Communication Control and Computing Technologies, ICCCCT 2010
Open Access	No