Dynamics of the level of deterministic chaos associated with gastric electrical uncoupling in dogs

Abstract

This study investigated the impact of gastric electrical uncoupling on the dynamics of the level of deterministic chaos in cutaneous gastric electrical signals. Eight-channel electrogastrograms (EGG) were recorded from 16 unconscious dogs. Controlled gastric electrical uncoupling was introduced by circumferentially cutting the whole gastric muscle at two different locations. Three separate 30-min EGG recordings were obtained from each dog in the three different states (basal, after the first cut, and after the second cut). The Lyapunov exponents were calculated from sixteen 6.31-min intervals with 75% overlap obtained from each channel in each state. Inadequate EGG signals from which the Lyapunov exponent could not be reliably calculated were quantitatively discarded. The variance and the standard deviation of the three Lyapunov exponent distributions obtained from each channel were studied, and the mean values were subjected to a Student t-test. In 65.6% of all studied channels, the level of chaos was significantly different (p< 0.01) after the first cut compared to the basal state, but no predominant direction of variation was observed (47. 7% increment vs. 52.5% decrement). After the second cut, 63.6% of the channels studied showed significantly greater Lyapunov exponent compared to the basal state, and 63.1% exhibited significantly greater (p< 0.01) level of chaos compared to the intercut state. The dynamics of the level of deterministic chaos in canine electrogastrograms is highly sensitive to severe gastric electrical uncoupling. Moreover, some channel configurations seem to be more sensitive than others in detecting uncoupling.

Wavelet analysis in a canine model of gastric electrical uncoupling

“…Consequently, by the end of the experiment, these circular myotomies divided the stomach in three parts of approximately equal dimensions. Similar type of experimental work was described before [12][13][14].…”

Analysis of Canine Model of Gastric Electrical Uncoupling Using Recurrence Quantification Analysis

“…The inverse of MAXLINE is related to the Lyapunov exponent (11), which is a measure of the level of chaos in the system under analysis. Large Lyapunov exponents are indicative of chaotic behavior (4,8). The calculation of these five statistical values was performed using the software package RQA v6.2 (14).…”

“…Gastric electrical uncoupling is the loss of synchronization in the sequential peristaltic contractions of the stomach, causing the inability of the organ to propel content distally in a synchronized fashion. Early detection of electrical uncoupling could be important in assessing gastric motility abnormalities, compared to the so-called "gastric dysrhythmias," which might not significantly affect gastric motor function if they are synchronized throughout the distal corpus and in the antrim (4). Detection of electrical uncoupling by statistically examining the EGG frequency spectra failed to recognize mild uncoupling (3), suggesting that Fourier analysis is probably not sufficient to identify the onset of this condition.…”

“…Detection of electrical uncoupling by statistically examining the EGG frequency spectra failed to recognize mild uncoupling (3), suggesting that Fourier analysis is probably not sufficient to identify the onset of this condition. The second problem is related to a recent finding that EGG signals may in fact be chaotic (4). The implication of this finding downgrades the usability of traditional methods, such as Fourier analysis, to analyze EGG signals, particularly for early onsets of gastric electrical uncoupling.…”

“…This traditional approach brings about two problems. The first is related to the analysis of EGG recordings from individuals with gastric electrical uncoupling (3,4). Gastric electrical uncoupling is the loss of synchronization in the sequential peristaltic contractions of the stomach, causing the inability of the organ to propel content distally in a synchronized fashion.…”