An Enhanced Technique for Recording and Analysis of Electrogastrogram using Active Electrodes

Abstract

Electrogastrogram (EGG) is obtained with the help of Active Electrode (AE) from the human being cutaneously. It is a non-invasive, easy procedure that is tried as a preliminary investigation to assess the need for endoscopy. Active electrode setup is proposed in this paper to acquire the myoelectrical activity of the stomach as it is of higher sensitivity in acquiring the EGG signals when compared to passive electrodes. Active electrode based acquisition is most reliable as signal loss is prevented. Interference is prevented completely by using appropriate filters and by using Electromagnetic Interference (EMI) shield. EGG recorded in more than hundred and fifty human being includes the normal individual and patients with digestive system disorders such us nausea, dyspepsia, vomiting, peptic ulcer, etc. A database is created for the analysis. The change in frequency and power for disorders in patients compared to normal individuals form the power spectrum plot. Wavelet Transform analysis includes Continuous Wavelet Transform (CWT) to analyze the signal for the diagnosis of various gastric disorders as mentioned above. In wavelet analysis, the data of a patient or normal individual is considered. The signal is reconstructed with a data obtained through a data scope. This input signal undergoes Principle Component Analysis (PCA) as a preprocessing manoeuvre and then the interference and noise in the EGG signals are removed to obtain de-noised signal. The denoised EGG signal is plotted for power spectral density estimation with Welch power spectral Density Estimation. As a result of the proposed method the power variation is found to be 40-52dB and frequency is detected as 6.0-8.5 cpm in preprandial and 1.5-2.5 cpm in postprandial for ulcer patients, 4-5 cpm in preprandial 1.5-2.8 cpm in postprandial for dyspepsia patients and 3.0-3.15 cpm for normal individuals.

Keywords: Active Electrode Electrogastrogram, Electromagnetic Interference, Preprandial, Postprandial, CWT

DOI: 10.4038/sljbmi.v1i1.1482

Sri Lanka Journal of Bio-Medical Informatics 2009;1(1): 21-27