Physiological interpretation of electrical impedance epigastrography measurements

Abstract

Measurement of the electrical impedance of the gastric region is carried out with the epigastrograph. This generates and applies alternating current around the abdominal area and measures the potential difference in order to determine the impedance externally, via electrodes. The change of epigastric impedance for a subject, given a meal after fasting, depends on the conductivity of the meal compared to the stomach and surrounding tissues. Typically a conductive meal has conductivity >7 mS cm(-1), non-conductive <2 mS cm(-1) and neutral about 4.5 mS cm(-1). Half-emptying times (T50s) from gastric emptying studies in volunteers using three test meals of 450 ml volume were obtained and found to be shorter than expected from the literature. The meals were a 10% glucose solution and two milk shakes of energy 1,300 kJ and 2,850 kJ, respectively. These electrical impedance epigastrography (EIE) measurements were carried out with scintigraphy. The T50 values of the latter were significantly longer. The direct comparison of the normalized experimental data obtained by both methods led to the concept that EIE measurements are mainly influenced by gastric secretion. Thus the EIE trace of a 'neutral' meal suggests the hypothesis that the volume of the meal is not the significant factor but is influenced by gastric acid secretions. Physiology of the gastric mucosa during the digestion of a meal and intragastric pH values also suggests this. Gastric function studies using EIE measurements may therefore reflect gastric ionic concentration rather than the volume of the contents of the stomach. In turn this could lead to the development of a non-invasive method for the continuous recording of gastric acid secretions.

Effects of occupational stress on the gastrointestinal tract

“…In fact, alterations in GIT motility are frequently viewed as signs of neuropathy of the myenteric plexus or other pathologies of neuropathic origin. Abnormal gastric emptying is considered a clinical marker for a gastric or intestinal motility disorder [61,62] . Quigley and other researchers have found a relationship between stress and delayed gastric emptying or other motor disturbances [63][64][65] .…”

Bio-Impedance and Synchronous Electrogastrogram to Evaluate Gastric Motility

“…The stomach, additionally, being a muscular bag with a small volume in the fasting state (approximately 50 ml) and becoming larger when a meal is ingested can be studied by EIP [14]. EIP is considered as the collection of data in the form of electrical impedance measurements at a suitable sampling rate, using surface electrodes from the gastric area.…”

Gastric motility functional study based on electrical bioimpedance measurements and simultaneous electrogastrography

“…Early research with the impedance method to measure digestion was mainly concentrated on gastric emptying measurement (Chaw et al, 2001;Giouvanoudi et al, 2003;Huerta-Franco et al, 2009). There is little research on extraction of gastric motility information (Garay et al, 2006;Soulsby et al, 2006;Giouvanoudi and Spyrou, 2008).…”