Original Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Sep 28, 2012; 18(36): 5027-5033
Published online Sep 28, 2012. doi: 10.3748/wjg.v18.i36.5027
Effect of psychological stress on gastric motility assessed by electrical bio-impedance
María Raquel Huerta-Franco, Miguel Vargas-Luna, Juana Berenice Montes-Frausto, Ismael Morales-Mata, Lorena Ramirez-Padilla
María Raquel Huerta-Franco, Ismael Morales-Mata, Lorena Ramirez-Padilla, Department of Applied Sciences to Work, Health Science Division, University of Guanajuato, 37320 Leon, Guanajuato, Mexico
Miguel Vargas-Luna, Juana Berenice Montes-Frausto, Department of Physical Engineering, Science and Engineering Division, University of Guanajuato, 37150 Leon, Guanajuato, Mexico
Author contributions: Huerta-Franco MR and Vargas-Luna M are experts on the use of bio-impedance for gastric evaluation, designed and conducted the study and wrote the manuscript; Morales-Mata I performed data acquisition and instrumentation review; Montes-Frausto JB contributed to data collection, reviewed the literature and analytical input; and Ramirez-Padilla L contributed to the psychological data collection and performed the psychological tests.
Supported by Research and Graduate Department, 2008-2010, University of Guanajuato
Correspondence to: Maria Raquel Huerta-Franco, PhD, Department of Applied Sciences to Work, Health Science Division, University of Guanajuato, Aquiles Serdan No. 924, Colonia Obregon, 37320 Leon, Guanajuato, Mexico. mrhuertafranco@ugto.mx
Telephone: +52-477-2569688 Fax: +52-477-7885100
Received: February 16, 2012
Revised: May 18, 2012
Accepted: May 26, 2012
Published online: September 28, 2012
Abstract

AIM: To evaluate gastric motility using electrical bio-impedance (EBI) and gastric changes as a result of stress induced by psychological tests.

METHODS: A group of 57 healthy women, aged 40-60 years, was recruited, and a clinical history and physical examination were performed. The women were free from severe anxiety, chronic or acute stress, severe depression, mental diseases and conditions that affect gastric activity. The women were evaluated under fasting conditions, and using a four-electrode configuration, the gastric signals were obtained through a BIOPAC MP-150 system. The volunteers were evaluated using the following paradigm: basal state, recording during the Stroop Test, intermediate resting period, recording during the Raven Test, and a final resting period. We analyzed the relative areas of the frequency spectrum: A1 (1-2 cpm), A2 (2-4 cpm), A3 (4-8 cpm), and A4 (8-12 cpm), as well as the median of area A2 + A3. The data were analyzed by an autoregressive method using a Butterworth filter with MatLab and Origin. Analysis of variance (ANOVA) and Friedman ANOVA (for nonparametric variables) were performed; in addition, pairs of groups were compared using the T dependent and Wilcoxon T tests.

RESULTS: The results of the main values of area A2 were not significantly different comparing the five steps of the experimental paradigm. Nevertheless, there was a tendency of this A2 region to decrease during the stress tests, with recuperation at the final resting step. When an extended gastric region was considered (1-4 cpm), significant differences with the psychological stress tests were present (F = 3.85, P = 0.005). The A3 region also showed significant changes when the stress psychological tests were administered (F = 7.25, P < 0.001). These differences were influenced by the changes in the adjacent gastric region of A2. The parameter that we proposed in previous studies for the evaluation of gastric motility by electrical bio-impedance (EBI) was the median of the area under the region from 2 to 8 cpm (A2 + A3). The mean values of these frequencies (median of the A2 + A3 area) with the stress test showed significant changes (F = 5.5, P < 0.001). The results of the Wilcoxon T test for the A4 area parameter, which is influenced by the breathing response, changed significantly during the Raven stress test (P < 0.05).

CONCLUSION: We confirm that the gastric response to acute psychological stress can be evaluated by short-term EBI.

Keywords: Psychological stress; Bio-impedance; Gastric motility