Isopower maps of the electrogastrogram (EGG) after total gastrectomy or total colectomy

Asia-Pacific guidelines for managing functional dyspepsia overlapping with other gastrointestinal symptoms

Contemporary systems for the diagnosis and management gastrointestinal symptoms not attributable to organic diseases (Functional GI Disorders, FGID, now renamed Disorders of Gut-Brain Interaction, DGBI) seek to categorize patients into narrowly defined symptom-based sub-classes to enable targeted treatment of patient cohorts with similar underlying putative pathophysiology. However, an overlap of symptom categories frequently occurs and has a negative impact on treatment outcomes. There is a lack of guidance on their management. An Asian Pacific Association of Gastroenterology (APAGE) working group was set up to develop clinical practice guidelines for management of patients with functional dyspepsia (FD) who have an overlap with another functional gastrointestinal disorder: FD with gastroesophageal reflux (FD-GERD), epigastric pain syndrome with irritable bowel syndrome (EPS-IBS), postprandial distress syndrome with IBS (PDS-IBS), and FD-Constipation. We identified putative pathophysiology to provide a basis for treatment recommendations. A management algorithm is presented to guide primary and secondary care clinicians.

Electrogastrography for psychophysiological research: Practical considerations, analysis pipeline, and normative data in a large sample

Electrogastrography (EGG) is the noninvasive electrophysiological technique used to record gastric electrical activity by means of cutaneous electrodes placed on the abdomen. EGG has been so far mostly used in clinical studies in gastroenterology, but it represents an attractive method to study brain-viscera interactions in psychophysiology. Compared to the literature on electrocardiography for instance, where practical recommendations and normative data are abundant, the literature on EGG in humans remains scarce. The aim of this article is threefold. First, we review the existing literature on the physiological basis of the EGG, pathways of brain-stomach interactions, and experimental findings in the cognitive neuroscience and psychophysiology literature. We then describe practical issues faced when recording the EGG in young healthy participants, from data acquisition to data analysis, and propose a semi-automated analysis pipeline together with associated MATLAB code. The analysis pipeline aims at identifying a regular rhythm that can be safely attributed to the stomach, through multiple steps. Finally, we apply these recording and analysis procedures in a large sample (N = 117) of healthy young adult male and female participants in a moderate (<5 hr) to prolonged (>10 hr) fasting state to establish the normative distribution of several EGG parameters. Our results are overall congruent with the clinical gastroenterology literature, but suggest using an electrode coverage extending to lower abdominal locations than current clinical guidelines. Our results indicate a marginal difference in EGG peak frequency between male and female participants, and that the gastric rhythm becomes more irregular after prolonged fasting.

The effects of stress during the mirror drawing test on electrogastrograms of subjects who underwent gastrointestinal surgery involving either total gastrectomy, distal gastrectomy, or total esophagectomy with colonic replacement

Electrogastrograms (EGGs) were recorded from 16 locations on the thoraco-abdominal surface to find the maximum absolute power foci during rest (RAP) and the maximum ratio of the % content during the mirror drawing test (MDT) compared to that during rest (%C-MDT/R) for both the 3 cpm (2.4–4.9) and 6 cpm (5.0–7.4) groups. The maximum foci were obtained from control subjects and those who received gastro-intestinal surgery via total gastrectomy (TG), distal gastrectomy (DG), and total esophagectomy with colonic replacement (CR). The control mean of the infraumbilical channels 10–16 (I) expressed as %C-MDT/R of the 3 cpm group was higher than the mean of the supraumbilical channels 1–9 (S) (I>S, P<0.001). The maximum focus of the 3-cpm %C-MDT/R was in the left umbilical area, while that of the 6-cpm %C-MDT/R was found bilaterally in the right epigastric and left umbilical areas, interposed by the lower %C-MDT/R gastric area. Therefore, the presence of gastric EGG inhibition and colonic facilitation are suggested to occur during MDT. In TG and DG, the foci of the %C-MDT/R in the 3-cpm group were located bilaterally in the right epigastric and left umbilical areas. The shifts of foci suggest colonic EGG facilitation. The mean S of the 3-cpm group was significantly higher than the mean I with CR (S>I, P<0.05). The maximum foci of the 3- and 6-cpm groups were in the epigastrium. These results suggest colonic EGG facilitation in the epigastrium, as the stomach has been removed and the original gastric location is instead occupied by the transverse colon in CR.

Correlations between anxiety and the stress responses of electrogastrography (EGG) induced by the mirror drawing test (MDT)

Electrogastrograms (EGGs) were recorded at 16 locations on the thoraco-abdominal surface at rest and then both during and after the acute stress of performing the mirror drawing test (MDT). A significant linear correlation with a negative slope was found between the anxiety scores and the ratio of the power content during MDT to the power content at rest (r) (MDTr(-1)) of the 3 cpm component from the epigastric channel 2 recording. In contrast, significant linear correlations with positive slopes were found between the anxiety scores and MDTr(-1) of the 6 cpm component of the recordings from the infraumbilical channels (channels 13, 15, and 16). The epigastric 3-cpm EGG activity reflects gastric myoelectric activity, while the infraumbilical 3- and 6-cpm activity reflects that of the colon. Therefore, these results seem to further support the previous report of the inhibition of gastric EGG by stress and the stress-mediated facilitation of colonic EGG (Homma S, J Smooth Muscle Res. 2012; 48(2-3): 47-57).

Application of a heat- and steam-generating sheet increases peripheral blood flow and induces parasympathetic predominance

To promote the practical application of a Japanese traditional medical treatment, such as hot compresses, we developed a plaster-type warming device consisting of a heat- and steam-generating sheet (HSG sheet). First, we tested its effects when applied to the anterior abdominal wall or lumbar region of women complaining of a tendency towards constipation. Application of the sheet to either region produced a feeling of comfort in the abdomen, as assessed by a survey of the subjects. The significant increases in the total hemoglobin observed in these regions suggested an increase in peripheral blood flow, and significant increases in the HF component on ECG and in the amplitude of gastric motility suggested parasympathetic predominance. We concluded that application of the HSG sheet improves the peripheral hemodynamics and autonomic regulation, induces a feeling of comfort in the abdomen, and provides a beneficial environment for the improvement of gastrointestinal movements.

Local differences in electrogastrographic indices associated with total gastrectomy, total colectomy, distal gastrectomy and colonic replacement

The electrogastrographic indices of spectral frequency, instability factor (IF), power amplitude, and power content (%) were compared between control subjects (C), and subjects following either total gastrectomy (TG), total colectomy (TC), distal gastrectomy (DG) or colonic replacement surgery (CR). In the fasting state, both the spectral frequency and IF of the epigastric 3-cycle per minute (cpm) group of the TC subjects were significantly lower than those indices in C, TG, DG, and CR subjects. In contrast, the power amplitude and power content of the epigastric 3-cpm group of both TG and DG subjects were significantly lower than those of C and TC subjects. The original epigastric waves of TG had remarkably high amplitudes. Furthermore, the absolute power of the epigastric 3-cpm of the TC subjects was 10 times higher than that in either the C or TG subjects. These results may be partially explained by the assumption that the recorded epigastric electrogastrography (EGG) is mainly contributed to by the 3-cpm myoelectric activity of the stomach and colon, while the infraumbilical EGG is mainly contributed to by the 3-cpm myoelectric activity of the colon. Topographic EGG maps visually supported these assumptions.

Local differences in electrogastrograms recorded from 16 locations on the human thoraco-abdominal surface

Local differences in the electrogastrographic (EGG) indices were studied. The indices include the spectral frequency, the instability factor (IF) of the spectral frequency, and the power content in addition to the usual power amplitude of 5 frequency groups as follows: the 1-cpm group (0-2.4), the 3-cpm group (2.5-4.9), the 6-cpm group (5.0-7.4), the 8-cpm group (7.5-9.9), and the 10-cpm group (10.0-12.9). In general, the infraumbilical frequency and the IF of both of the 3- and 6-cpm groups were higher than those of the epigastric frequencies. In contrast, both the epigastric power amplitude and the power content of the 3- and 6-cpm groups were higher than those of the infraumbilical ones. Mapping of the absolute power amplitude and superimposing the maximal power foci further visualized and clarified the local differences in the epigastric and infraumbilical myoelectrical activity, especially of gastric and colonic activity.

Trans-cutaneous electrogastrographic study of gastric myoelectric activity in transposed intrathoracic stomach after esophagectomy

We examined the feasibility of trans-cutaneous electrogastrography (EGG) in recording myoelectric activity of the transposed thoracic stomach after esophagectomy. Nineteen patients who had Ivor-Lewis esophagectomy were studied. The EGG signal was recorded using cutaneous electrodes placed over the lower sternum. Eleven patients who underwent total gastrectomy served as controls. Normal rhythm pattern (2.4-3.6 cpm > or = 70%) and power ratio (PR > or = 2) was observed in five and 12 patients, respectively, after esophagectomy. The observation of normal gastric rhythm was more frequent in the postprandial period in the esophagectomy group (median 42.6%vs. 7.4%, P = 0.01), and the PR was significantly higher (median 2.27 vs. 1.38, P = 0.013) than the gastrectomy group. Feeding further increased the prevalence of normal gastric slow wave in the esophagectomy group (median 14.8% to 42.6%, P = 0.002) and improved the stability of dominant frequency (median 78% to 67%, P = 0.015). We conclude that gastric myoelectric activities of thoracic transposed stomach can be detected from cutaneous sternal electrodes. This represented a preservation of gastric motility even when the stomach is pulled up to the thorax as a substitute for the esophagus.

Fasting and postprandial small intestinal slow waves non-invasively measured in subjects with total gastrectomy

BACKGROUND AND AIM

Slow wave is essential to initiate gastrointestinal tract motility. Subjects with total gastrectomy (TG) provide an opportunity to study small intestinal slow wave in the absence of stomach interference. The aims of this study were to determine the origin of 3 cycles per min (cpm) slow wave recorded via electrogastrogram (EGG) and the characteristics of putative small intestinal slow waves in TG subjects.

METHODS

Thirty-three subjects with TG (25 male, age: 44-83 years) were consecutively enrolled. In each subject, the myoelectricity-like signals of the gastrointestinal tract were recorded using 3-channel EGG. Fourier transform-based spectral analysis was performed to derive the EGG parameters including dominant frequency/power, % normal rhythm (2-4 cpm), and power ratio.

RESULTS

Neither visual nor spectral analysis of the EGG revealed any waves at a frequency of about 3 cpm. The most frequently observed peaks in the power spectra of all subjects were those at approximately 1, approximately 6 and approximately 11 cpm with occurrences of 97%, 6.1% and 90.9%, respectively. Based on visual analysis of all recorded signals, the approximately 11 cpm signal was exactly rhythmically recorded rather than the approximately 1 cpm. The recorded approximately 11 cpm wave had a frequency of 10.9 +/- 1.0 cpm in the fasting state and 10.9 +/- 1.3 cpm in the fed state (NS), and a power of 31.5 +/- 3.2 dB in the fasting state and 35.2 +/- 3.8 dB in the fed state (P < 0.0001). None of other factors, including sex, age, and body mass index, had any impact on this approximately 11 cpm wave.

CONCLUSIONS

Small intestinal slow wave can be recorded non-invasively using EGG via cutaneous electrodes in TG subjects. Sex, age and body mass index have no effect on the intestinal slow waves. The power rather than frequency of intestinal slow wave is increased after a solid meal.

A biomagnetic assessment of colonic electrical activity in pigs

The electrical control activity of the large intestine was recorded in six pigs using a SQUID magnetometer. The study was performed in pre- and post-colectomy/sham-colectomy conditions. The biomagnetic field associated with colonic ECA changed drastically in subjects that underwent the colectomy procedure, whereas the signal for the control animals was nearly unchanged. Power spectral analysis was used to determine the average changes of dominant frequency and amplitude between baseline versus colectomy and sham-colectomy conditions. The dominant frequency was increased by 68 +/- 24% (versus 2 +/- 3% in control). The amplitude was decreased by 69 +/- 24% (versus 13 +/- 17% in control). This is the first study of transabdominal magnetic fields associated with colonic ECA, suggests some of the side effects generated in colectomy surgery and shows the utility of the biomagnetic technique in studies of the large intestine.

Correlations between the responses of electrogastrograms, heart rate and respiratory rate to the stress of the mirror drawing test in human subjects

An electrogastrogram (EGG) recorded on the skin is believed to reflect the electrical activity of the gastrointestinal tract. In this study, linear correlations were calculated for the EGG spectral frequencies and the power ratios, changes in heart and respiratory rate before and during mirror drawing test (MDT) stress and after having meals, with the changes in the sympathetic tone indicator (LF/HF) and HADS anxiety and depression scores in human subjects (n=48). Depression scores had a negative linear correlation with the EGG resting frequencies of the epigastric and supraumbilical 6 cpm groups (5.0-7.4 cpm). Anxiety scores had a positive linear correlation with the EGG area power ratio of the resting to MDT stress responses of the epigastric and infraumbilical 6 cpm groups (6 cpm area during MDT/that during fasting rest). The resting LF/HF had a positive linear correlation with the EGG area power ratio of the resting to MDT stress responses of the epigastric and infraumbilical 3 cpm groups (2.5-4.9 cpm). The resting LF/HF ratio had a negative correlation with the area power ratio of the resting to postprandial responses (postprandial power/resting power) in the epigatric, supraumbilical and infraumbilical 6 cpm groups. The resting LF/HF ratio had a positive linear correlation with the heart rate at rest and during MDT-stress. In contrast, the resting LF/HF ratio had a negative linear correlation with the respiratory rate at rest and during MDT-stress. EGGs of the surface electrical activities of the gastrointestinal tract were influenced by acute MDT-stress and their frequencies and their response power ratios were correlated linearly with anxiety scores, depression scores and the sympathetic tone indicator, the LF/HF ratio.

Electrogastrographic activity in patients who received proximal gastrectomy plus jejunal interposition or total gastrectomy plus jejunal interposition

Electrogastrograms (EGGs) were recorded in patients both before and after receiving proximal gastrectomy plus jejunal interposition (PGJI) or just after receiving total gastrectomy plus jejunal interposition (TGJI). Intraluminal pressure was also recorded in some postoperative patients. The EGG 3 cpm component (2.5-4.9 cpm) remained after PGJI, but subsequently decreased with a significant reduction in the preoperative to postoperative ratio of the 3 cpm components (P<0.05). The mean frequency of the 3 cpm components increased significantly after PGJI (P<0.05) and its instability factor increased. The EGG 10 cpm components became relatively dominant compared to other frequency components in 2 out of 8 of patients having PGJI but the mean amplitude of 10 cpm decreased. In TGJI patients, only the 10 cpm component was conspicuous in EGG as in the case of total gastrectomy and Roux en Y anastomosis procedures. The spectral frequencies of intraluminal pressure in the interposed jejunum were similar to the EGG of 10 cpm components both in the case of PGJI and TGJI patients. In conclusion, surface EGG could record the electrical activities of the interposed jejunum more easily in patients having had TGJI than in PGJI.

Motor and electrogastrographic activity of the gastric tube formed after esophagectomy

In order to characterize the motor activity of a surgically constructed gastric tube, several hours of ambulatory intraluminal pressure recordings were performed in 6 patients following esophagectomy and gastric tube construction. Whole pressure waves were spectrally analyzed by Fast Fourier Transform (FFT). Simultaneous abdominal and thoracic electrogastrograms (EGGs) were recorded for about 20 min both before and after meals during ambulatory pressure recording. The pressure waves and EGGs for each 20 min recording were analyzed by the maximal entropy method (MEM). While the motility index of the pressure waves decreased after a meal, the 3 cpm component of these waves (2.4-3.7 cpm) increased significantly (n=6, P<0.05). Both bradygastria (0-2.4 cpm) and the duodeno-respiratory component (10-15 cpm) decreased, while the tachygastria component (3.7-10 cpm) increased, although these differences were not significant. The peak power of the gastric tube abdominal EGGs was significantly larger than that of control abdominal or thoracic EGGs in each of the 1 cpm (0-2.4 cpm), 6 cpm (5.0-7.4) and 8 cpm components (7.5-9.9). The thoracic EGG consisted mainly of the 3 cpm component, while the spectral amplitudes of the 1, 6, 8 and 10 cpm components were below 6% of the 3 cpm component. The peak spectral frequency both of the intraluminal pressure waves by FFT and of the thoracic EGGs by MEM occurred within the 3 cpm component. A cross correlation of about 0.2-0.3 occurred between the thoracic EGGs and the intraluminal pressure waves. Thus the gastric tube seems to preserve most of the original gastric motor characteristics and to contribute as a substitute for the original esophagus and stomach.

Electrogastrography: basic knowledge, recording, processing and its clinical applications

The slow wave (SW) of the gastrointestinal (GI) tract mainly functions to trigger the onset of spike to elicit smooth muscle contraction, which provides the essential power of motility. Smooth muscle myogenic control activity or SW is believed to originate in the interstitial cells of Cajal (ICC). The electrical coupling promotes interaction between muscle cells, and ICC additionally contribute to SW rhythmicity. Stomach SW originates in the proximal body showing the continuous rhythmic change in the membrane potential and propagates normally to the distal antrum with a regular rhythm of approximately 3 c.p.m. A technique using electrodes positioned on the abdominal skin to pick up stomach rhythmic SW refers to electrogastrography (EGG). The stomach SW amplitude is very weak, while many visceral organs also produce rhythmic electricities, for example heartbeat, respiration, other organs of the GI tract and even body movements. Thus noise other than SW should be filtered out during the recording, while motion artifacts are visually examined and deleted. Finally, the best signal among all recordings is selected to compute EGG parameters based on spectral analysis. The latter is done not only to tranform frequency domain to time domain but also to provide information of time variability in frequency. Obtained EGG parameters include dominant frequency/power, % normal rhythm, % bradygastria, % tachygastria, instability coefficient and power ratio. Clinical experience in EGG has been markedly accumulated since its rapid evolution. In contrast, lack of standardized methodology in terms of electrode positions, recording periods, test meals, analytic software and normal reference values makes the significance of EGG recording controversial. Unlike imaging or manometrical studies, stomach motility disorders are not diagnosed based only on abnormal EGG parameters. Limitations of EGG recording, processing, computation, acceptable normal parameters, technique and reading should be known to conduct subjective assessments when EGG is used to resolve stomach dysfunction. Understanding basic SW physiology, recording methodology and indications may open EGG as a new domain to approach the stomach motor dysfunction.

The effects of stress in response to mirror drawing test trials on the electrogastrogram, heart rate and respiratory rate of human subjects

Electrogastrograms (EGGs), heart and respiratory rates were recorded simultaneously from human subjects and analyzed spectrally by the maximal entropy method. The stress of the mirror drawing test (MDT) significantly increased both the heart and respiratory rates with an associated increase in LF/HF ratios. MDT stress, however, increased (excited groups) or decreased (inhibited groups) the power amplitude and the power ratio, (peak power during MDT)/(peak power during rest), of the 1-cpm (0-2.4 cpm), 3-cpm (2.5-4.9), 6-cpm (5.0-7.4), 8-cpm (7.5-9.9) and 10-cpm (10.0-12.9) spectral group components of the EGG recording of the electrical activity of the gastrointestinal tract. The depression scores of the subjects in the MDT stress excited group were higher and their resting frequencies were significantly lower than those of the MDT stress inhibited groups in each of the epigastric, supra-umbilical and infra-umbilical 6-cpm frequency groups but not in the epigastric 1-cpm frequency group. Anxiety scores of the MDT stress excited groups were significantly higher and their power ratios were also significantly higher than those of the inhibited groups in each of the epigastric 10-cpm, the supra-umbilical 6-cpm and the infra-umbilical 1- and 3-cpm frequency groups. Therefore, depression scores appeared to have inhibitory effects on the resting EGG frequencies, while anxiety scores appeared to have facilitatory effects on the EGG power ratio during MDT stress. It is suggested that analysis of EGG under MDT stress would provide a measure of the stress sensitivity of the electrical activity of the human gastrointestinal tract.

Spectral analysis of colonic intraluminal pressure in patients who received a colonic replacement following radical esophagectomy

The aim of this study was to evaluate the motor activity of the interposed colonic segment in patients who had received a colonic replacement following radical esophagectomy using spectral analysis and a 24 hr activity graph. The 24-hr ambulatory pressure waves were recorded in the replaced colon after esophagectomy (n=8) using a solid-state manometric catheter (MicroDigitrapper, Synetics). Motility and spectral analyses of the intraluminal pressure waves were performed by Multigram and Gastrosoft (Synetics). It was revealed that after a meal the 3 cpm (cycles per minute) component of the motility index increased but the 12-15 cpm component decreased. The diurnal rhythm showed that colonic motility was high in the daytime and low during sleep. In contrast, duodenal motility was relatively high even during sleep. The motility index increased as the postoperative period increased. The motility of the replaced colon was higher during the daytime and after meals. The higher motility after meals was characterized by an increase in the 3 cpm component. These motor characteristics may help the function of the replaced colon as a substitute for the esophagus.

Electrical activity from colon overlaps with normal gastric electrical activity in cutaneous recordings

The stability of EGG recordings is affected by a variety of artifacts. The aim of this study was to investigate possible overlapping of dominant frequencies in recorded cutaneous electrical activity arising simultaneously from the stomach and/or colon. Ten normal volunteers, eight posttotal colectomy patients, and four patients posttotal gastrectomy were studied. Fasting cutaneous recordings were obtained using four pediatric ECG electrodes attached to the abdominal surface. Electrical activity was recorded and digitally analyzed using custom-designed software. Spectral analysis after gastrectomy and colectomy showed persistence of power peaks in the gastric electrical activity range of frequency (2.5-3.75 cpm). In conclusion, noninvasively obtained colonic frequencies overlap EGG. This hypothesis is supported by the persistence of power peaks in the EGG range of frequency after gastrectomy and colectomy. Therefore, we conclude that contribution of electrical activity arising from the colon could substantially affect EGG recordings.

Isopower mapping of electrogastrograms in short-bowel syndrome

Methods for making topographic or isopower electrogastrographic (EGG) maps and for obtaining maximum power foci (MPFs) by means of 27-channel EGG recordings are briefly described. The methods are applied to short-bowel syndrome (SBS). The gastro-intestinal tract is traced by videofluorograms after X-ray-opaque barium has been ingested. The MPFs are generally located on the trace of the gastro-intestinal tract. The gastric area is occupied by 3 cycles x min(-1) (up to 28% of total MPFs) and 6 cycles x min(-1) MPFs (26%). The trace of the small intestine is occupied mainly by 8 cycles x min(-1) (39%) and 10 cycles x min(-1) (43%) MPFs. The trace of the colon is occupied almost evenly by all five spectral frequency groups, that is, by 1 (58%), 3 (53%), 6 (48%), 8 (57%) and 10 cycles x min(-1) (42%). Most interestingly, the numbers of 8-10 cycles x min(-1) power foci found on EGG maps (including MPFs and relatively higher power foci) are proportional to the remaining length at operation and to the length of the remaining small intestine in the long-term, over 6 years postoperatively. It is therefore possible to follow approximately the trace of the gastero-intestinal tract.