Gastric motility measurement and evaluation of functional dyspepsia by a bio-impedance method.

In order to investigate the complex course of the electrical and mechanical processes of functional dyspepsia (FD), it is necessary to extract gastric motility information on both electricity and mechanism. According to the clinical standardization, 36 volunteers with functional dyspepsia were selected. The signal processing device has been designed by Chongqing University of Posts and Telecommunications. Multi-resolution analysis (MRA) decomposed the two signals of impedance gastric motility (IGM) and electrogastrogram (EGG) collected from the body surface. The wavelet transform is addressed to separate the IGM and EGG signals from impedance signals due to breathing and blood flow. By means of the energy and frequency spectrum analysis technique, the signals can be classified according to the dominant power and dominant frequency. Some indices, such as frequencies of EGG and IGM, signal power spectrum and dynamic spectrum, the rates of rhythm and power for the normal EGG and IGM and so on, can also be calculated. The primary experiments of gastric motility measurement and evaluation are executed by including healthy humans (control group: CG) and patients with FD (pathologic group: PG). There are significant differences in the temporal-domain and frequency-domain properties between the two groups. The main frequency of the CG belongs to 2-4 CPM and is clear and very regular, while the main frequency of the PG is much disordered. The peak of the maximal power of the CG belongs to 2-4 CPM and 1-2 CPM for the PG. The percentage of normal frequency (PNF) for the CG is 0.704 +/- 0.255 and 0.402 +/- 1.145 for the PG. The frequency instability coefficient (FIC) for the CG is 0.182 +/- 0.059 and 0.374 +/- 0.086 for the PG. The percentage of normal power (PNP) for the CG is 0.592 +/- 0.044 and 0.468 +/- 0.142 for the PG. The power instability coefficient (PIC) for the CG is 1.576 +/- 0.481 and 4.006 +/- 0.711 for the PG. The results of the experiments show that the proposed method of impedance can be a potential tool for the noninvasive assessment of gastric motility under gastrointestinal physiology and pathology conditions.