Epigastric electrical impedance for the quantitative determination of the gastric acidity

Gastric acid secretion: changes during a century

The advances in knowledge of gastric physiology within the past century have been the most exciting and important in this area of interest for many decades. The aim of this presentation consists of a comprehensive review of the extensive recent literature on this topic in order to highlight milestones in the field of gastric physiology, in particular in gastric acid secretion, gastric pathophysiology, acid-related diseases and use of acid regulatory drugs. Moreover, in the 21st century there have been many epidemiologic changes as well as a decrease of Helicobacter pylori infection and gastric cancer together with an increase of gastroesophageal reflux disease and the related increase of pomp proton inhibitor wide use.

Gastric motility measurement and evaluation based on electrical-mechanical composite mechanism

Gastric motility and emptying are a composite course involving electrical activity and mechanical contraction. In the research of gastric motility, the electrical activity should be closely connected to the subsequent mechanical contraction based on the understanding of electrical-mechanical composite mechanism. Existing simulation research and clinical research suggest that electrogastrogram (EGG) signals can provide physiological time scales, and gastric motility can be extracted from impedance signals. According to the coupling of the myoelectric activity and the mechanical contraction of the stomach, the correlation analysis of multiple signals can be performed. And then the influence of various factors such as the range, time and transmission distance of the gastric contraction can be deeply explored. The method combining gastric impedance and synchronous EGG measurements is effective and promising for evaluating gastric motility.

Electrical bioimpedance gastric motility measurement based on an electrical-mechanical composite mechanism

AIM: To introduce a bioimpedance gastric motility measurement method based on an electrical-mechanical composite concept and a preliminary clinical application.

METHODS: A noninvasive gastric motility measurement method combining electrogastrogram (EGG) and impedance gastric motility (IGM) test was used. Preliminary clinical application studies of patients with functional dyspepsia (FD) and gastritis, as well as healthy controls, were carried out. Twenty-eight FD patients (mean age 40.9 ± 9.7 years) and 40 healthy volunteers (mean age 30.9 ± 7.9 years) were involved. IGM spectrum was measured for both the healthy subjects and FD patients, and outcomes were compared in the FD patients before treatment and 1 wk and 3 wk after treatment. IGM parameters were obtained from 30 erosive gastritis patients (mean age 50.5 ± 13.0 years) and 40 healthy adults, and IGM and EGG results were compared in the gastritis patients before treatment and 1 wk after treatment.

RESULTS: There were significant differences in the IGM parameters between the FD patients and healthy subjects, and FD patients had a poorer gastric motility [percentage of normal frequency (PNF) 70.8 ± 25.5 in healthy subjects and 28.3 ± 16.9 in FD patients, P < 0.01]. After 1 wk administration of domperidone 10 mg, tid, the gastric motility of FD patients was not improved, although the EGG of the patients had returned to normal. After 3 wk of treatment, the IGM rhythm of the FD patients became normal. There was a significant difference in IGM parameters between the two groups (PNF 70.4 ± 25.5 for healthy subjects and 36.1 ± 21.8 for gastritis patients, P < 0.05). The EGG rhythm of the gastritis patients returned to normal (frequency instability coefficient 2.22 ± 0.43 before treatment and 1.77 ± 0.19 one wk after treatment, P < 0.05) after 1 wk of treatment with sodium rabeprazole tablets, 10 mg, qd, po, qm, while some IGM parameters showed a tendency toward improvement but had not reached statistical significance.

CONCLUSION: The electrical-mechanical composite measurement method showed an attractive clinical application prospect in gastric motility research and evaluation.

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

For some time now, the research on gastric motility and function has fallen behind in the amount of research on gastric endocrine, exocrine secretion, and gastric morphology. In this paper, a noninvasive method to study gastric motility was developed, taking bioimpedance measurements over the gastric area simultaneously with the electrogastrography (EGG). This is based on the concept of observing and analyzing simultaneously the intrinsic electrical gastric activity (basic electric rhythm) and the mechanical gastric activity. Additionally, preliminary clinical studies of healthy subjects and subjects with functional dyspepsia (FD) and gastritis were carried out. The impedance gastric motility (IGM) measurements of the healthy and FD subjects were compared, along with the studies of the FD subjects before treatment and after one week and three weeks of treatment. We also compared IGM measurements of healthy subjects and subjects with erosive gastritis, along with the studies of the subjects with erosive gastritis before treatment and after one week of treatment. Results show that FD subjects have poor gastric motility (P<0.01). After a week of treatment, the gastric motility of FD subjects was not yet improved although the EGG had returned to normal by this time. By three weeks of treatment, the regular IGM rhythm returned in FD subjects. There was a significant difference of IGM parameters between the gastritis and healthy subjects (P<0.05). The EGG rhythm of the gastritis subjects returned to normal at one week post-treatment, while IGM parameters showed a trend to improvement (P>0.05), These results suggest the possibility of clinic application of the proposed method.

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

For some time now, the research on gastric motility and function has fallen behind in the amount of research on gastric endocrine, exocrine secretion, and gastric morphology. In this paper, a noninvasive method to study gastric motility was developed, taking bioimpedance measurements over the gastric area simultaneously with the electrogastrography (EGG). This is based on the concept of observing and analyzing simultaneously the intrinsic electrical gastric activity (basic electric rhythm) and the mechanical gastric activity. Additionally, preliminary clinical studies of healthy subjects and subjects with functional dyspepsia (FD) and gastritis were carried out. The impedance gastric motility (IGM) measurements of the healthy and FD subjects were compared, along with the studies of the FD subjects before treatment and after one week and three weeks of treatment. We also compared IGM measurements of healthy subjects and subjects with erosive gastritis, along with the studies of the subjects with erosive gastritis before treatment and after one week of treatment. Results show that FD subjects have poor gastric motility (P<0.01). After a week of treatment, the gastric motility of FD subjects was not yet improved although the EGG had returned to normal by this time. By three weeks of treatment, the regular IGM rhythm returned in FD subjects. There was a significant difference of IGM parameters between the gastritis and healthy subjects (P<0.05). The EGG rhythm of the gastritis subjects returned to normal at one week post-treatment, while IGM parameters showed a trend to improvement (P>0.05), These results suggest the possibility of clinic application of the proposed method.

Electrical bioimpedance and other techniques for gastric emptying and motility evaluation

The aim of this article is to identify non-invasive, inexpensive, highly sensitive and accurate techniques for evaluating and diagnosing gastric diseases. In the case of the stomach, there are highly sensitive and specific methods for assessing gastric motility and emptying (GME). However, these methods are invasive, expensive and/or not technically feasible for all clinicians and patients. We present a summary of the most relevant international information on non-invasive methods and techniques for clinically evaluating GME. We particularly emphasize the potential of gastric electrical bioimpedance (EBI). EBI was initially used mainly in gastric emptying studies and was essentially abandoned in favor of techniques such as electrogastrography and the gold standard, scintigraphy. The current research evaluating the utility of gastric EBI either combines this technique with other frequently used techniques or uses new methods for gastric EBI signal analysis. In this context, we discuss our results and those of other researchers who have worked with gastric EBI. In this review article, we present the following topics: (1) a description of the oldest methods and procedures for evaluating GME; (2) an explanation of the methods currently used to evaluate gastric activity; and (3) a perspective on the newest trends and techniques in clinical and research GME methods. We conclude that gastric EBI is a highly effective non-invasive, easy to use and inexpensive technique for assessing GME.

Use of electrical bioimpedance for gastric motility measurement and evaluation

Electrical bioimpedance technology is a measurement method to extract biomedical information associated with the physiological and pathological states of human body according to the electrical properties of tissue and organs. It has many outstanding advantages such as noninvasiveness, cheapness, convenience and rich function information. According to the electrical properties of the stomach tissue or the food in the stomach and the characteristics of food digestion, electrical bioimpedance methods permit to extract physiological and pathological information associated with gastric motility, investigate gastric contraction, peristalsis, transmission and emptying, and measure and evaluate gastric motility function noninvasively. In this article, we reveiw the development history of electrical bioimpedance technology and the characteristics of gastric motility impedance signal, and introduce the bioimpedance methods for measurement of gastric motility based on the concept of electrical-mechanical coupling. Besides, we also summarize the application of bioimpedance methods in the basic research of gastric motility, in the measurement of gastric motility in patients with functional dyspepsia, in the evaluation of gastric motility in patients with erosive gastritis, and in the detection and screening of gastric cancer. Moreover, we put forward some suggestions on the future development directions of bioimpedance methods for measurement of gastric motility.

Gastric exocrine and endocrine secretion

PURPOSE OF REVIEW

This review summarizes the last year's literature regarding the regulation and measurement of gastric exocrine and endocrine secretion.

RECENT FINDINGS

Parietal cells, distributed along much of the length of the oxyntic glands, with highest density in the neck and base, secrete HCl as well as transforming growth factor-alpha, amphiregulin, heparin-binding epidermal growth factor-like growth factor, and sonic hedgehog. Acid facilitates the digestion of protein and absorption of iron, calcium, vitamin B(12) as well as prevents bacterial overgrowth, enteric infection, and possibly food allergy. The major stimulants of acid secretion are gastrin, histamine, and acetylcholine. Ghrelin and orexin also stimulate acid secretion. The main inhibitor of acid secretion is somatostatin. Nitric oxide and dopamine also inhibit acid secretion. Although Helicobacter pylori is associated with duodenal ulcer disease, most patients infected with the organism produce less than normal amount of acid. The cytoskeletal proteins ezrin and moesin participate in parietal cell acid and chief cell pepsinogen secretion, respectively.

SUMMARY

Despite our vast knowledge, the understanding of the regulation of gastric acid secretion in health and disease is far from complete. A better understanding of the pathways and mechanisms regulating acid secretion should lead to improved management of patients with acid-induced disorders as well as those who secrete too little acid.

Effects of metoclopramide on gastric motility measured by short-term bio-impedance

AIM: To analyze the accuracy of short-term bio-impedance as a means of measuring gastric motility.

METHODS: We evaluated differences in the short-term electrical bio-impedance signal from the gastric region in the following conditions: (1) fasting state, (2) after the administration of metoclopramide (a drug that induces an increase in gastric motility) and (3) after food ingestion in 23 healthy volunteers. We recorded the real component of the electrical impedance signal from the gastric region for 1000 s. We performed a Fast Fourier Transform (FFT) on this data and then compared the signal among the fasting, medicated, and postprandial conditions using the median of the area under the curve, the relative area under the curve and the main peak activity.

RESULTS: The median of the area under the curve of the frequency range in the region between 2-8 cycles per minute (cpm) decreased from 4.7 cpm in the fasting condition to 4.0 cpm in the medicated state (t = 3.32, P = 0.004). This concurred with the decrease seen in the relative area under the FFT curve in the region from 4 to 8 cpm from 38.3% to 26.6% (t = 2.81, P = 0.012) and the increase in area in the region from 2 to 4 cpm from 22.4% to 27.7%, respectively (t = -2.5, P = 0.022). Finally the main peak position also decreased in the region from 2 to 8 cpm. Main peak activity in the fasting state was 4.72 cpm and declined to 3.45 cpm in the medicated state (t = 2.47, P = 0.025). There was a decrease from the fasting state to the postprandial state at 3.02 cpm (t = 4.0, P = 0.0013).

CONCLUSION: Short-term electrical bio-impedance can assess gastric motility changes in individuals experiencing gastric stress by analyzing the area medians and relative areas under the FFT curve.

Use of short-term bio-impedance for gastric motility assessment

Gastric motility (GM) has been assessed using bio-impedance (BI) techniques in the time domain using short term recordings and analyzing mainly the median of the area under the fast Fourier transform (FFT) spectra. The BI technique has been applied to the gastric system mainly for gastric emptying (GE) studies. However, gastric motility evaluation using BI has not been fully implemented. In this study, we propose the use of the BI technique for the evaluation of gastric motility considering global features of the fast FFT spectra. The study was performed in eleven healthy subjects who were evaluated in fasting and postprandial conditions. The results indicate that the use of the median of the area under the FFT spectra is equivalent to the use of the main peak of the spectra to determine the changes in gastric motility from the fasting to the postprandial state. This demonstrates that BI is a valid technique for gastric motility evaluation in short time recordings.