Proposal for a New Diagram to Evaluate the Form of the Attractor Reconstructed from Electrogastrography

Yasuyuki Matsuura^1,2*, Hiroki Takada³, Kiyoko Yokoyama⁴ and Katsuhiko Shimada¹

¹Graduate School of Natural Science, Nagoya City University, Mizuho-ku, Nagoya 467-8501, Japan
²JSPS Research Fellow
³Gifu University of Medical Science, 795-1 Nagamine, Ichihiraga, Seki 501-3892, Japan
⁴Graduate School of Design and Architecture, Nagoya City University, Chikusa-ku, Nagoya 464-0083, Japan
*E-mail address: y.matsuura@nsc.nagoya-cu.ac.jp

(Received September 18, 2008; Accepted November 2, 2008)

Keywords: Wayland Algorithm, Translation Error, Maximum Lyapunov Exponent (MLE), Electrogastrography (EGG)

Abstract. Electrogastrography (EGG) measures the electrical activity of the stomach through electrodes placed on the abdomen, which is primarily rhythmical. We analyzed the attractor reconstructed from EGG data and the factors characterising diseases resulting from constipation and erosive gastritis. The degree of determinism and complexity in the attractor are measured using the translation error and the maximum Lyapunov exponent, respectively. A new diagram is proposed to evaluate differences in the waveform of time-series data and to classify EGG data for the sitting and supine positions. Postural change enhanced the complexity in the attractor. Changes were also observed in the waveform characteristics.