Peak-Frequency Histogram Similarity of Bowel Sounds for the Evaluation of Intestinal Conditions

Many patients worldwide suffer from constipation, which reduces their quality of life (QOL) over the long term. Carbonated water intake is expected to improve constipation by improving intestinal motility. Conversely, carbonated water intake is believed to alter bowel status via the intestinal contents (gas and liquid) and intestinal distension, and these changes may be reflected in bowel sound (BS) peak-frequency histograms. In this study, to identify changes in intestinal conditions before and after the ingestion of liquid (i.e., water/carbonated water intake), we used a novel evaluation index, namely peak-frequency histogram similarity (PFHS), which measures the changes in the peak-frequency histogram before and after liquid intake. We considered 13 subjects who participated in a liquid intake test, and PFHS values before and after carbonated water intake were found to be significantly lower than those before and after cold water intake (p < 0.01). However, when using conventional frequency-domain features, this difference was not identified. The results obtained in this study suggest that PFHS can identify changes in bowel status (including intestinal gas and distension) that could not be found using conventional BS frequency domain features. Our findings provide a novel method of research for investigators to non-invasively monitor and evaluate intestinal conditions such as the intestinal gas volume and intestinal distention, which are associated with constipation, using a BS-based approach.

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