Frequency components of the electrogastrogram and their correlations with gastrointestinal contractions in humans

Synergistic augmentation of rhythmic myogenic contractions of human stomach by arginine vasopressin and adrenaline: Implications for the induction of nausea

BACKGROUND AND PURPOSE

Nausea is associated with the hormonal secretion of vasopressin and adrenaline, although their actions in inducing nausea is poorly understood. Here, we have investigated their actions on human stomach muscle.

EXPERIMENTAL APPROACH

Muscle strips were suspended in tissue baths and neuronal-/non-neuronally-mediated contractions were measured. Custom software analysed eight motility parameters defining spontaneous phasic non-neuronally mediated contractions. Receptor distributions were assessed by qPCR and immunofluorescence.

KEY RESULTS

V_1A receptors and α₁ -adrenoceptors were located on muscle as well as interstitial cells of Cajal (ICCs). Myogenic contractions of human proximal and distal stomach (respectively, 2.6 ± 0.1 and 2.7 ± 0.0 per minute; n = 44) were larger in the distal area (1.1 ± 0.1 and 5.0 ± 0.1 mN), developing relatively slowly (proximal) or rapidly (distal). Vasopressin caused tonic (proximal) or short-lived (distal) increases in muscle tone and increased myogenic contraction amplitude, frequency and rate (acting at V_1A receptors; thresholds 10^-11 -10^-10  M); by contrast, cholinergically mediated contractions were unaffected. Oxytocin acted similarly to vasopressin but less potently, at OT receptors). Adrenaline increased (10^-10 -10^-5  M; α₁ -adrenoceptors) and decreased (≥10^-6  M; β-adrenoceptors) muscle tone and enhanced/reduced myogenic contractions. Cholinergically mediated contractions were reduced (α₂ -adrenoceptors). Combined, vasopressin (10^-9  M) and adrenaline (10^-8  M) increased muscle tone and phasic myogenic activity in a synergistic manner.

CONCLUSIONS AND IMPLICATIONS

Vasopressin and adrenaline increased human gastric tone and myogenic contraction amplitude, rate of contraction and frequency. In combination, their actions were further increased in a synergistic manner. Such activity may promote nausea.

Characteristics of myoelectrical activities along the small intestine and their responses to test meals of different glycemic index in rats

The purpose of this study was to characterize intestinal myoelectrical activity along the small intestine and investigate its responses to test meals with different glycemic index at different locations. Sixteen rats were implanted with electrodes in the serosal surface of the duodenum, jejunum, and ileum. Intestinal myoelectrical activities were recorded from these electrodes for 30 min in the fasting state and 3 h after four kinds of meals with different glycemic index, together with the assessment of blood glucose. The results were as follows: 1) in the fasting state, the percentage of normal intestinal slow waves (%NISW) showed no difference; however, the dominant frequency (DF), power (DP), and percentage of spike activity superimposed on the intestinal slow wave (NS/M) were progressively decreased along the entire small intestine; 2) regular solid meal and Ensure solicited no changes in any parameters of intestinal myoelectrical activity; whereas glucose and glucose + glucagon significantly altered the %NISW, DF, DP, and NS/M, and the effects on the proximal intestine were opposite to those in the distal intestine; and 3) postprandial blood glucose level was significantly correlated with %NISW along the entire small intestine. We found that that, in addition to the well-known frequency gradient, there is also a gradual decrease in the DP and spikes along the small intestine in the fasting state. Glucose and hyperglycemic meals inhibit myoelectrical activities in the proximal small intestine but result in enhanced but more dysrhythmic intestinal myoelectrical activities. There is a significant negative correlation between the normality of intestinal slow waves and blood glucose.

Association between gastric myoelectric activity disturbances and dyspeptic symptoms in gastrointestinal cancer patients

PURPOSE

Dyspeptic symptoms present a severe problem in gastrointestinal (GI) cancer patients. The aim of the study was to analyze an association between gastric myoelectric activity changes and dyspeptic symptoms in gastrointestinal cancer patients.

MATERIAL AND METHODS

The study included 80 patients (37 men and 43 women, mean age 61.2 ± 7.8 years) diagnosed with GI tract malignancies: colon (group A), rectal (group B) and gastric cancers (group C). Gastric myoelectric activity in a preprandial and postprandial state was determined by means of a 4-channel electrogastrography. Autonomic nervous system was studied based on heart rate variability analysis. The results were compared with the data from healthy asymptomatic controls.

RESULTS

In a fasted state, GI cancer patients presented with lesser percentages of normogastria time (A:44.23 vs. B:46.5 vs. C:47.10 vs. Control:78.2%) and average percentage slow wave coupling (ACSWC) (A:47.1 vs. B:50.8 vs. C:47.2 vs. Control:74.9%), and with higher values of dominant power (A:12.8 vs. B:11.7 vs. C:12.3 vs. Control:10.9) than the controls. Patients did not show an improvement in the percentage of normogastria time, dominant power, dominant frequency and ACSWC in response to food. The severity of dyspeptic symptoms correlated with the values of electrogastrography parameters. Patients showed lower values of heart rate variability parameters than the healthy controls, that indicate abnormal autonomic nervous system activity.

CONCLUSION

GI cancers affect the gastric myoelectric activity, decreasing normogastria and slow wave coupling. These patients do not show adequate gastric motility response to food. Impaired gastric electric motility may result from cancer-induced autonomic disturbances.

Autonomic dysfunction of gastric motility in major depression

BACKGROUND

Patients suffering from major depressive disorder (MDD) often complain about somatic symptoms. Cardiac complaints have been examined predominantly. However, gastrointestinal complaints are also reported frequently and are associated with worse outcomes. The research concerning changes in gastric motility of these patients is rather sparse. The aim of our study was to determine dysfunction of gastric motility and gastrointestinal symptoms in MDD. The duration and severity of MDD were examined regarding its influence over gastric emptying.

METHODS

Gastric emptying was determined by a ¹³C-acetate breath test in patients with MDD (n = 29) and healthy control subjects (n = 51). Prior to this, depressive illness was operationalized using external and self-assessment scales (HAMD-21, MADRS, BDI, CGI). Whether the severity or duration of MDD influenced the gastric emptying parameters was examined using Spearman's correlation. In addition, autonomic complaints were recorded by means of an ANS score. Each ANS score item was determined using a Mann-Whitney U or Kruskal-Wallis test concerning the gastric emptying parameters.

RESULTS

There was a significant difference in the parameters of the maximum gastric emptying rate (T_max) and gastric half emptying time T_1/2b between patients with MDD and healthy control subjects (T_max 66.21min vs 53.35min, p < 0.006, T_1/2b 207.59min vs 133.27min, p < 0.005). There was a significant negative correlation between T_max and the severity of MDD determined with the depression rating scales BDI (Spearman's rank - 0.521, p = 0.013) and HAMD-21 (r - 0.384, p = 0.048). No correlation was found between the duration of MDD and the maximum gastric emptying rate (r - 0.125, p = 0.519) and gastric half emptying time (r - 0.62, p = 0.749).

CONCLUSION

Gastrointestinal motility is significantly impaired in patients with MDD compared to healthy control subjects. Autonomic complaints were indicated frequently in MDD patients. The duration of MDD had no influence over the time of gastric emptying. There was a significant negative correlation between the severity of MDD and T_max, indicating that the T_max was reached earlier with the progression of MDD. The slowing of gastric motility in MDD patients is likely a result of a dysfunction of the autonomic nervous system.

Diabetic gastroparesis alters the biomagnetic signature of the gastric slow wave

BACKGROUND

Gastroparesis is characterized by delayed gastric emptying without mechanical obstruction, but remains difficult to diagnose and distinguish from other gastrointestinal (GI) disorders. Gastroparesis affects the gastric slow wave, but non-invasive assessment has been limited to the electrogastrogram (EGG), which reliably characterizes temporal dynamics but does not provide spatial information.

METHODS

We measured gastric slow wave parameters from the EGG and magnetogastrogram (MGG) in patients with gastroparesis and in healthy controls. In addition to dominant frequency (DF) and percentage power distribution (PPD), we measured the propagation velocity from MGG spatiotemporal patterns and the percentage of slow wave coupling (%SWC) from EGG.

KEY RESULTS

No significant difference in DF was found between patients and controls. Gastroparesis patients had lower percentages of normogastric frequencies (60 ± 6% vs 78 ± 4%, p < 0.05), and higher brady (9 ± 2% vs 2 ± 1%, p < 0.05) and tachygastric (31 ± 2% vs 19 ± 1%, p < 0.05) frequency content postprandial, indicative of uncoupling. Propagation patterns were substantially different in patients and longitudinal propagation velocity was retrograde at 4.3 ± 2.9 mm/s vs anterograde at 7.4 ± 1.0 mm/s for controls (p < 0.01). No difference was found in %SWC from EGG.

CONCLUSIONS & INFERENCES

Gastric slow wave parameters obtained from MGG recordings distinguish gastroparesis patients from controls. Assessment of slow wave propagation may prove critical to characterization of underlying disease processes. Future studies should determine pathologic indicators from MGG associated with other functional gastric disorders, and whether multichannel EGG with appropriate signal processing also reveals pathology.

Pacemakers of the upper divisions of the digestive tract

Pacemaker cells of the upper portion of the digestive tract were studied by electromyography of various parts of the stomach and duodenum. Pacemaker cells of the stomach were located mainly at the interface between the lesser curvature and cardia and in the proximal part of the antrum and were characterized by high spontaneous slow-wave and spike activities. Antroduodenal coordination contributes to sequential motor activity of the stomach and duodenum. Pacemaker cells were characterized by a specific shape and a lesser number of myofibrils.

Inhibitory effects of desvenlafaxine on gastric slow waves, antral contractions, and gastric accommodation mediated via the sympathetic mechanism in dogs

Desvenlafaxine succinate (DVS; Pristiq) is a new antidepressant, serotonin-norepinephrine reuptake inhibitor. Antidepressants have been widely used for the treatment of functional gastrointestinal disorders. Possible roles of DVS on gastrointestinal motility have not been studied. The aim of this study was to investigate the effects of DVS on gastric slow waves (GSW), antral contractions, and gastric accommodation in dogs. Fifteen healthy dogs implanted with gastric serosal electrodes and a gastric cannula were studied in four separate sessions: control, DVS (50 mg), propranolol (1 mg·kg(-1)·h(-1)), and propranolol + DVS. GSW were measured via the gastric serosal electrodes. Antral contractions were assessed via an intraluminal manometric catheter inserted via the gastric cannula. The sympathovagal activity was assessed from the spectral analysis of the heart rate variability signal. Gastric tone was measured by barostat via an intragastric balloon inserted into the fundus via the gastric cannula. In the postprandial period, in comparison with the control, DVS reduced the percentage of normal GSW (P=0.001) and increased the percentage of tachygastria (P=0.005) and bradygastria (P=0.002). Simultaneously, DVS increased the sympathetic activity (P=0.006) and the sympathovagal ratio (low frequency/high frequency; P=0.044). These effects were blocked by propranolol. DVS attenuated postprandial antral contractions and gastric accommodation. The postprandial antral contractile index (area under the curve) was decreased by 26% with DVS (P=0.013), and gastric accommodation was decreased by about 50% with DVS (P < 0.001). The inhibitory effect of DVS on gastric accommodation was blocked by propranolol. DVS inhibits gastric contractions, slow waves, and accommodation in the fed state. These inhibitory effects are associated with an increased sympathetic modulation in the gastrointestinal system. Cautions should be made when DVS is used for treating patients with depression and gastric motility disorders.

Gastric dysmotility in healthy first-degree relatives of patients with schizophrenia

Gastric dysmotility has been reported in patients suffering from major depression or schizophrenia. An increased sympathetic activity modulating the gastric pacemaker located in the antrum of the stomach has been suggested as the underlying pathology. Similar to patients suffering from schizophrenia, their first-degree relatives showed alterations in cardiac autonomic modulation. Here we aimed to investigate gastric myoelectrical activity in healthy relatives of patients suffering from paranoid schizophrenia. Electrogastrography (EGG) was performed before and after test meal ingestion in 20 patients with paranoid schizophrenia, 20 of their first-degree relatives and 20 healthy matched controls. Autonomic and abdominal symptoms were assessed by the autonomic symptom score as previously reported. Autonomic parameters were correlated with the positive and negative syndrome scale (PANSS). Only minimal differences were observed before test meal ingestion between relatives and controls. In contrast, after test meal ingestion we observed a significantly increased tachygastria within the signal of the gastric pacemaker in relatives compared to controls, whereas normogastria was reduced. Significant difference between relatives and controls were also found for postprandial ICDF (instability coefficient of dominant frequency) and slow wave, which represents the dominant frequency of gastric pacemaker activity, indicating gastric dysmotility in relatives. Between relatives and patients just a difference for ICDP (instability coefficient of dominant power) was observed. After stimulation of the enteric nervous system we have observed an increased sympathetic modulation in first-degree relatives of patients suffering from schizophrenia. This result adds evidence to an ongoing debate on the genetic influence of autonomic dysfunction in the disease.

Gastric dysmotility in major depression

BACKGROUND

Somatic symptoms of the gastrointestinal tract occur frequently in major depressive disorder (MDD) and might be associated with the known autonomic imbalance in the disease. Hence, we have investigated gastric electrical activity in patients suffering from major depression before and after treatment by means of electrogastrography (EGG) to investigate a putative association with either the disease state and its symptoms or its relation to the treatment.

METHODS

EGG readings before and after ingestion of a test meal of 27 patients suffering from major depression were recorded before and after treatment with antidepressants and compared with age-matched controls. Abdominal symptoms were rated by a specific Autonomic Nervous Symptom-score.

RESULTS

We found a significantly increased amount of tachygastria before and after medication, indicating increased sympathetic modulation. A significant difference was observed for the instability coefficients before and after medication, indicating gastric dysmotility in our patients prior to treatment. The elevated approximate entropy measure points to increased complexity and dysregulation. Furthermore, we have observed a correlation between subjective sensation of sweating and dry mouth with the sympathetic parameter tachygastria.

DISCUSSION

Our results suggest that major depression is associated with gastric dysrhythmia possibly caused by increased sympathetic modulation. Linear and non-linear EGG measures emphasize a possible role of the autonomic nervous system in the development of gastric symptoms. The treatment with antidepressants seems to increase the activity of the sympathetic nervous system, without aggravating gastric symptoms. The association of increased sympathetic modulation with somatic symptoms was indicated by correlation analysis with these symptoms.

Association of the status of interstitial cells of Cajal and electrogastrogram parameters, gastric emptying and symptoms in patients with gastroparesis

Our goal was to investigate associations between the status of interstitial cells of Cajal (ICC) and electrogastrogram (EGG) parameters, gastric emptying and symptoms in a large cohort of patients with gastroparesis. Forty-one patients with refractory gastroparesis who were referred for gastric electrical stimulation (GES) underwent full thickness gastric (antrum) biopsy during the surgery to place the GES device. The biopsy samples were stained with c-kit and scored for the presence of ICC based on criteria obtained from 10 controls. All patients underwent EGG recordings, a 4-h standardized scintigraphic gastric emptying study and symptom assessment prior to the surgery. Based on antral biopsy, 15 patients (36%) had almost no ICC (ICC- group) and 26 patients had adequate cell numbers (ICC+ group). EGG recordings in the ICC- group displayed significantly less normal slow waves than in the ICC+ group both in the fasting and fed states. Tachygastria in the ICC- group was significantly more than in the ICC+ group both in the fasting (32 +/- 8%vs 11 +/- 2%) and fed states (27 +/- 9%vs 12 +/- 2%). There was no statistical difference in gastric emptying, symptom severity of gastroparesis, aetiology, age and gender between the two groups. Severely depleted ICC occurs in up to 36% of gastroparetic patients and significantly correlates with an abnormal EGG. Severely depleted ICC does not correlate with the severity of gastroparesis as assessed by gastric emptying or symptom status but did result in a poorer symptomatic response to GES. These data suggest that the EGG may have a role for predicting ICC status during clinical evaluation of gastroparetic patients.

Gastric dysmotility in patients with major depression

BACKGROUND

Depressed patients frequently complain about vegetative symptoms. The aim of the present study was to evaluate gastric electrical activity in patients suffering from major depression in relation to their symptoms.

METHODS

Electrogastrography (EGG) was performed before and after a test meal ingestion in 21 patients suffering from major depression and control subjects. A structured interview was used to assess the severity of clinical as well as abdominal symptoms.

RESULTS

Patients presented with significantly elevated proportions of tachygastria. Significant differences were found for the parameter arrhythmia, the coefficient of dominant frequency and slow wave after the test meal ingestion. A positive correlation was found between tachygastria and ANS score as well as tachygastria and the item "sweating".

LIMITATIONS

Further studies are warranted to include more patients and to investigate interaction with specific antidepressive drugs.

DISCUSSION

This is the first study demonstrating an increased amount of tachygastria in patients suffering from major depression which might be caused by increased sympathetic modulation. The correlation of tachygastria with the amount of gastric symptoms underlines the clinical significance of this finding.

Detection of gastric dysrhythmia using WT and ANN in diabetic gastroparesis patients

Gastric myoelectrical activity can be measured by a noninvasive technique called electrogastrography where surface electrodes are placed on the epigastric area of the abdomen. The electrogastrogram (EGG) signal is by nature a nonstationary signal in terms of its frequency, amplitude and wave shape. Unlike the other methods discrete wavelet analysis (DWT) was designed for nonstationary signals. For automatic assessment of EGG, we used artificial neural networks (ANNs) that have been widely employed in pattern recognition due to their great potential of high performance, flexibility, robust fault tolerance, cost-effective functionality and capability for real-time applications. So we developed a new method for classification of EGG based on DWT and ANN.

Evaluation of the effects of mastication and swallowing on gastric motility using electrogastrography

OBJECTIVES

The influence of mastication and swallowing on gastric motor function was evaluated by electrogastrography (EGG) and abdominal ultrasonography.

METHODS

The subjects were 30 elderly patients with tubal feeding without mastication and swallowing (T group) and 30 elderly controls who processed food by mastication and swallowing (C group). Gastric motor function was percutaneously examined before and after the ingestion of 250 ml of a liquid diet using an electrogastrograph (NIPRO EGG, A and D, Tokyo, Japan). The cross-sectional area of the gastric antrum was measured at 1 and 30 min after the start of ingestion of the liquid diet by external ultrasonography of the abdomen, and the gastric excretion function was evaluated. Furthermore, the spectral analysis of heart rate variability was performed using Holter electrocardiograms before and after ingestion. The low frequency power (LF power, 0.04-0.15 Hz), high frequency power (HF power, 0.15-0.40 Hz), and the LF/HF ratio were determined.

RESULTS

The peak amplitude at 3 cycles per minute (cpm) was significantly increased after ingestion in the C and T groups (p<0.05), and the ratio of increase was significantly lower in the T group (p<0.05). The mean amplitude for the brady-gastria and tachy-gastria was significantly higher in the T group than in the C group (p<0.05). The gastric excretion function, as evaluated by external ultrasonography of the abdomen, was significantly lower in the T group than in the C group (p<0.05). An analysis of heart rate variability demonstrated that the HF power, a parameter of parasympathetic activity, after ingestion was significantly higher in the C group than in the T group (p<0.05). No changes in LF power or LF/HF ratio, parameters of sympathetic activity, were induced by ingestion in either the C or T groups.

CONCLUSIONS

The parasympathetic nerve dominantly controls gastric motor function, but autonomic nervous activity is reduced in patients who are unable to masticate and swallow food, resulting in adverse effects on gastric motor function and excretion function. Mastication and swallowing not only prepare food for passage from the oral cavity to the esophagus but are also important in terms of subsequent events that occur in stomach. It has been proposed that autonomic nervous activity might be involved in mastication and swallowing.

The role of electrogastrography and gastrointestinal hormones in chemotherapy-related dyspeptic symptoms

BACKGROUND

The aim of this study was to investigate the relationship among motility disorders, dyspeptic symptoms, and plasma levels of gastrointestinal hormones in cancer patients who were well controlled for post-chemotherapy emesis.

METHODS

Twenty-five cancer patients treated with standard dosages of antiemetics and chemotherapies completed the study. Gastrointestinal symptoms were investigated by detailed questionnaire and visual analog score. Motility was investigated by cutaneous electrogastrography, and by blood levels of gastrin, serotonin, vasopressin, and substance P, before and 7 days after chemotherapy.

RESULTS

Before chemotherapy, no patient complained of dyspeptic symptoms, and no differences in electrogastrography (EGG) or in circulating peptide levels were found between patients who developed dyspepsia and those who did not. After chemotherapy, 13 patients suffered from dysmotility-like symptoms (total symptom score, 11.5 [2.5-37.9]; median value and 5th-95th percentiles), with susceptibility to nausea, early satiety, and postprandial fullness being the major complaints. As regards EGG parameters, a significant reduction (P = 0.04; Mann-Whitney test) in the normal slow-wave percentage and significantly increased tachygastria percentage were found in dyspeptic patients compared with symptom-free patients. The tachygastria percentage was significantly associated with susceptibility to nausea score, in a non-linear fashion (R2 = 0.37). Dyspeptic patients showed lower levels of substance P and gastrin than patients who were not dyspeptic, but this difference had no clinical significance for dyspepsia.

CONCLUSIONS

Chemotherapy may induce upper gastrointestinal symptoms suggestive of motility disorders. These dyspeptic symptoms were associated with EGG alterations, but not with variations in circulating peptides. Other hormones or pathophysiological factors, not considered in the present work, could be actively involved in these dyspeptic symptoms.

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.

Alteration of gastric myoelectrical and autonomic activities with audio stimulation in healthy humans

OBJECTIVE

Cold or emotional stress was reported to affect gastric myoelectrical activity. The aim of this study was to investigate the effects of music or noise on gastric myoelectrical activity and autonomic function in healthy volunteers.

MATERIALS AND METHODS

The study was performed in 10 fasted healthy volunteers and included 30 min at baseline, 30 min of classical music via headphones and 30 min of loud household noises via headphones. The electrogastrogram (EGG) readings were recorded simultaneously with the electrocardiogram (ECG) recording.

RESULTS

Both classical music and noise altered the regularity of gastric slow waves. The percentage of normal 2-4 cycles/min (cpm) waves was reduced from 77.9 +/- 4.7% at baseline to 66.9 +/- 5.4% during music (p < 0.006) and 67.7 +/-5.4% during noise (p < 0.05). The reduction was attributed to a significant increase in bradygastria (15.8 +/- 3.9% versus 9.8 +/- 2.6%, p < 0.04) with the music and a significant increase in arrhythmia (7.4 +/- 1.6% versus 2.0 +/- 1.1%, p < 0.02) with the noise. The dominant frequency and power of the EGG were, however, not altered with either music or noise. Neither music nor noise had any effect on the autonomic function assessed by the heart rate variability.

CONCLUSIONS

Audio stimulation, with both music and noise, alters the rhythmicity of gastric slow waves. Classical music seems to increase bradygastria, whereas, household noise may increase arrhythmia. The effect of audio stimulation on the gastric slow wave does not seem to involve sympathetic or vagal efferent pathways assessed by the spectral analysis of heart rate variability.

Electrogastrography reveals post-prandial gastric dysmotility in children with cystic fibrosis

OBJECTIVES

Cystic fibrosis patients have a wide spectrum of gastrointestinal disorders. The aim of this study was to investigate the function of gastroenteric neuromusculature and its response to a prokinetic.

METHODS

14 CF children aged 8.6 + 1.3 years were studied by electrogastrography and compared to 10 age-matched controls. A second recording was performed in CF patients after administration of cisapride (0.3 mg/kg). Parameters analyzed were percentage of normal gastric rhythm (2.0 to 4.0 cpm), percentage of tachygastria (4.0 to 9.0 cpm), dominant frequency instability coefficient and power ratio.

RESULTS

CF and control groups were not different in age, height or weight. A significant post-prandial increase in percentage of tachygastria (26.7 + 4.5 versus 12.4 + 2.6; P < 0.05) was seen in CF patients, which was not corrected by cisapride. The power ratio showed a statistical increase in 3 cpm (3.7 + 0.8 versus 1.6 + 0.3; P < 0.05) and in tachygastria (5.3 + 1.2 versus 1.7 + 0.4; P < 0.03) in CF compared with controls. Cisapride had an effect on tachygastria power ratio (3.0 + 0.5; P < 0.04). Analysis of normal rhythm and the dominant frequency instability coefficient were not statistically different in CF and controls.

CONCLUSION

This study provides evidence of gastric dysmotility in CF patients.

Electrogastrography abnormality in eating disorders

Eating disorders are common psychiatric disorders in young women. The aim of the present study was to evaluate the gastric electrical activity of patients with eating disorders and its relation to their symptoms. The electrogastrography (EGG) was performed before and after a water load test for outpatients with eating disorders (n = 36; 14 anorexia nervosa, 14 bulimia nervosa, eight eating disorder not otherwise specified) and healthy women (n = 19). A structured interview (Eating Disorder Examination) was used to assess clinical symptoms. The percentage of normal gastric myoelectrical power was significantly smaller in the eating disorder patients (44.5% vs 74.2%; P < 0.05), while the percentage of bradygastric power was significantly greater, both before and after the water load test compared with the control subjects (30.4% vs 10.4%; P < 0.05). In addition, moderate correlation was found between the duration of illness and the percentage of bradygastria (P < 0.05). In conclusion, it is suggested that longstanding abnormal eating in patients with eating disorders may induce disturbances to gastric motor function, resulting in their abnormal, eating-related behavior, and form a symptomatic vicious circle. The EGG may be a promising method for determining the pathophysiology of eating disorders and for developing effective therapeutic approaches.

Biomagnetic detection of gastric electrical activity in normal and vagotomized rabbits

We recorded the vector magnetogastrogram (MGG) due to gastric electrical activity (GEA) in normal rabbits using a Superconducting QUantum Interference Device (SQUID) magnetometer and measured the degree of correlation of the MGG with 24 channels of serosal electrodes. The vector magnetometer allows us to non-invasively record three orthogonal magnetic field components and project the recorded magnetic field vector into arbitrary directions. We optimized the magnetic field vector direction to obtain the highest possible correlation with each serosal electrode recording. We performed a vagotomy and examined spatial and temporal changes in the serosal potential and in the transabdominal magnetic field. We obtained spatial information by mapping the recorded signals to the electrode positions in the gastric musculature. Temporal evidence of uncoupling was observed in spectral analyses of both serosal electrode and SQUID magnetometer recordings. We conclude that non-invasive recordings of the vector magnetogastrogram reflect underlying serosal potentials as well as pathophysiological changes following vagotomy.

Effects of dim or bright-light exposure during the daytime on human gastrointestinal activity

On the basis of our previous findings that bright-light exposure during the daytime has profound influence on physiological parameters such as melatonin secretion and tympanic temperature in humans, we proposed the hypothesis that bright vs. dim light-exposure during the daytime has a different influence on the activity of the digestive system via the endocrine and/or autonomic nervous system. To examine this hypothesis, we conducted a series of counterbalanced experiments in which subjects stayed the daytime (7:00 to 15:00h) under either a dim (80 lux) or bright (5,000 lux) light condition. We measured gastrointestinal activity using a breath hydrogen (indicative of carbohydrate malabsorption) and an electrogastrography (EGG, indicative of gastric myoelectric activity) test. The results showed the postprandial breath hydrogen excretion during the following nighttime period after daytime exposure to the dim-light condition was significantly higher than under the bright-light condition (p < 0.05). In addition, the spectrum total power of the EGG recorded after taking the evening meal was significantly lower for the dim than bright-light condition (p < 0.05). These results support our hypothesis and indicate that dim-light exposure during the daytime suppresses the digestion of the evening meal, resulting in malabsorption of dietary carbohydrates in it.

Gastric electrical activity and gastric emptying in preterm newborns fed standard and hydrolysate formulas

BACKGROUND

Because infant formulas containing hydrolyzed cow milk protein are used to reduce feeding intolerance and to improve gastric emptying, the effect on gastrointestinal motility of a hydrolysate formula was compared with that of a standard preterm formula.

METHODS

Thirty-six preterm newborns with a gestational age of 32.2 +/- 2.3 weeks were assigned randomly to standard formula or hydrolyzed formula. Cutaneous electrogastrography and ultrasound examination of gastric emptying were performed simultaneously to evaluate gastrointestinal motility before and after the test meal. All recording sessions were performed 1 week after infants had reached full enteral feeding.

RESULTS

No significant difference in gastrointestinal symptoms was noted in the newborns fed the different formulas. In particular, regurgitation and vomiting were observed in 78% versus 64% of preterm newborns after standard and hydrolyzed formula, respectively (Fisher exact test, not significant). No differences were found in terms of gastric electrical activity and gastric emptying time between the two groups.

CONCLUSIONS

It seems unnecessary to use hydrolysate formulas to improve motility in preterm infants.

Protective effect of amtolmetin guacyl versus placebo diclofenac and misoprostol in healthy volunteers evaluated as gastric electrical activity in alcohol-induced stomach damage

Amtolmetin guacyl (AMG) is a nonsteroidal antiinflammatory drug (NSAID) of high therapeutic activity and free of damaging effects on the gastrointestinal tract. Since acute ulcer and nausea have been found to be associated with gastric dysrhythmias, cutaneous electrogastrography and ultrasonographic study of the gastric emptying time were performed simultaneously in 24 healthy volunteers before and for 180 min after a liquid meal with 0.5 g/kg body weight of alcohol in double-blind, placebo-controlled, crossover studies. Before the recording session, each subject had taken placebo, AMG, a standard NSAID, or a gastric protective drug for four days. Alcohol administration increased the tachygastria percentage while diclofenac, AMG, and misoprostol alone did not induce gastrointestinal symptoms and gastric dysrhythmias. As regards alcohol-induced gastric dysrhythmia, placebo and diclofenac showed a clear increase in tachygastria while AMG and misoprostol did not. AMG is able to induce a normalization of gastric dysrhythmia induced by alcohol administration probably due to its peculiar mechanism of action, which involves capsaicin and CGRP pathways.

Ambulatory electrogastrography in patients with sclerodermia, delayed gastric emptying, dyspepsia, and irritable bowel syndrome. Is there any clinical relevance?

Background: Changes in electrogastrographic parameters are described in patients with irritable bowel syndrome, sclerodermia, dyspepsia, and delayed gastric emptying in static measurements. However, no information is available about changes in ambulatory measurements. The objective of this study was to find parameters that discriminate between these diseases using cutaneous 24-h-electrogastrography. Methods: Cutaneous 24-h electrogastrography (EGG) measurements were taken from 20 patients with dyspepsia, 10 patients with systemic sclerosis (sclerodermia, SSc), 7 patients with irritable bowel syndrome (IBS), 7 patients with delayed gastric emptying, and 10 healthy volunteers. Measurements were made using a DIGITRAPPER EGG (Synectics Medical Inc., Stockholm, Sweden) and the accompanying computerized data analysis package (ElectroGastroGram Version 6.30, Gastrosoft Inc., Synectics Medical Inc., Stockholm, Sweden). Frequency and power were compared pre- and postprandially, as well as during the entire day of measurement. Results: The 24-h measurements in healthy volunteers revealed 45.00%+/-12.12% normal values (2.4-3.7 cpm), 30.10%+/-7.15% bradygastric values (<2.4 cpm), and 24.20%+/-7.76% tachygastric values (>3.7 cpm). There was no significant change in frequency between rest and motion, but there was a significant increase in power (P<0.05). There was significantly more bradygastria in patients with dyspepsia periprandially as well as after 24 h (P<0.01) than in healthy volunteers. The mean power of patients with dyspepsia was significantly higher than that of patients with IBS (P<0.05). Conclusion: Cutaneous 24-h-EGG may be used as an additional means of differentiating between dyspepsia and IBS.

Volume conductor effects on the spatial resolution of magnetic fields and electric potentials from gastrointestinal electrical activity

An analysis of the relative capabilities of methods for magnetic and electric detection of gastrointestinal electrical activity is presented. The model employed is the first volume conductor model for magnetic fields from GEA to appear in the literature. A mathematical model is introduced for the electric potential and magnetic field from intestinal electrical activity in terms of the spatial filters that relate the bioelectric sources with the external magnetic fields and potentials. The forward spatial filters are low-pass functions of spatial frequency, so more superficial external fields and potentials contain less spatial information than fields and potentials near the source. Inverse spatial filters, which are reciprocals of the forward filters, are high-pass functions and must be regularised by windowing. Because of the conductivity discontinuities introduced by low-conductivity fat layers in the abdomen, the electric potentials recorded outside these layers required more regularisation than the magnetic fields, and thus, the spatial resolution of the magnetic fields from intestinal electrical activity is higher than the spatial resolution of the external potentials. In this study, two smooth muscle sources separated by 5cm were adequately resolved magnetically, but not resolved electrically. Thus, sources are more accurately localized and imaged using magnetic measurements than using measurements of electric potential.

Effect of dialysis modalities on gastric myoelectrical activity in end-stage renal disease patients

Gastric motility is controlled by gastric myoelectrical activity, which propagates from the proximal body to the distal antrum at a frequency of 3 cycles/min. In uremic patients, dyspeptic symptoms are common. To investigate whether dialysis modality affects gastric myoelectrical activity in uremic patients, we performed electrogastrography (EGG) in 41 patients without diabetes with end-stage renal disease (ESRD) undergoing hemodialysis (HD; n = 22) and continuous ambulatory peritoneal dialysis (CAPD; n = 19). EGG was performed noninvasively using abdominal surface electrodes in the fasting state before and 4 hours after HD and at empty and 2 hours after CAPD with 2,000 mL of dialysate. There were no significant differences in age, sex, body weight, duration of dialysis, and percentage of patients with upper gastrointestinal (UGI) symptoms (63.6% versus 42.1%). CAPD patients had significantly lower serum albumin levels (3.4 +/- 0.4 versus 3.9 +/- 0.4 g/dL; P < 0.05), greater serum total-cholesterol levels (189 +/- 33 versus 157 +/- 36 mg/dL; P: < 0.05), and greater percentages of patient with early satiety (42.1% versus 13.6%; P < 0.05) than HD patients. Dominant power significantly increased after HD (251.3 +/- 157.5 versus 512.9 +/- 390.0 dB; P < 0.05) but seemed to decrease after CAPD without statistical significance (416.2 +/- 323.6 versus 283.8 +/- 280.7 dB). There was no difference in the normal slow-wave frequency (NSWF) between HD and CAPD patients (predialysis, 60.7% +/- 29.3% versus 52.2% +/- 36.7%; postdialysis, 56.3% +/- 32.0% versus 50.9% +/- 34.2%). Tachygastria significantly increased after CAPD (pre-CAPD, 2.35% +/- 4.3% versus post-CAPD, 10.0% +/- 14.8%; P < 0.05). There was a significant correlation between changes in tachygastria after CAPD and grade of early satiety in CAPD patients with UGI symptoms (r = 0.74; P: < 0.05). Changes in NSWF after CAPD significantly correlated with age (r = -0.51; P: < 0.05). In conclusion, dialysis modalities seem to have different effects on gastric myoelectrical activity in patients with ESRD.

Effect of gastric myoelectric activity on carbohydrate absorption of fruit juice in children

Juices have a different rate of gastric emptying than other foods. This may alter the rate of delivery of carbohydrates to the small bowel for absorption. The aim of the study is to demonstrate that faster gastric emptying is associated with greater production of hydrogen through a randomized, crossover study of 39 healthy children. The electrogastrography (indicator of the gastric myoelectric activities) and breath hydrogen tests (indicator of carbohydrate malabsorption) were performed at baseline and after ingestion of 240 to 330 mL of grape or pear juice given in a random order. The cutaneous electrogastrogram was analyzed by running spectral analysis to compute pre- and postprandial period dominant power (PDP) and running spectrum total power (RSTP). Postprandial PDP and RSTP were higher (p < 0.02) in the pear juice group than in the grape juice group, suggesting higher antral myoelectric activities. Twenty three percent of the subjects had significant movement artifacts that suggested discomfort after drinking pear juice compared to 5% after grape juice (p < 0.03). Breath hydrogen test was more frequently positive (increase >20 part per million [ppm] above baseline) after pear juice (52.2%; mean, 36 +/- 33 ppm) than after grape juice (4.3%, 6 +/- 6 ppm). In a multiple regression analysis, the most predictive independent variable of hydrogen concentration was found to be either postprandial PDP (r2 = 0.24; p < 0.002), or RSTP (r2 = 0.37; p < 0.001). Juices affect gastric myoelectric activity. Grape juice induces lower antral myoelectric activities and is better absorbed. The malabsorption of carbohydrates of juices is in part related to their effect on the gastric physiology.

Gastric myoelectric activity in patients with end-stage liver disease

BACKGROUND

Abnormalities of gastrointestinal motility and transit time have been reported in association with end-stage liver disease. Motility abnormalities could be routinely studied if a simple noninvasive test were available. The electrogastrogram is a cutaneous measure of gastric myoelectric activity and correlates well with serosal recordings of gastric myoelectric activity. The aim of this study was to evaluate gastric myoelectric activity in patients with end-stage liver disease.

METHODS

Fourteen patients with end-stage liver disease had gastric myoelectric activity measured with the electrogastrogram. An electrogastrogram was considered abnormal when normal gastric slow waves were seen less than 70% of the time or there was no increase in the electrogastrogram amplitude after a meal.

RESULTS

Abnormal electrogastrograms were present in 8 of 14 (57%) end-stage liver disease patients.

CONCLUSIONS

Abnormal gastric myoelectric activity is common in end-stage liver disease.

Real-time multichannel computerized electrogastrograph

The purpose of this study was to develop a real-time multichannel computerized electrogastrograph (EGG) to measure and analyze electrical signals from the human abdominal surface. A soft-contact matrix composed of 25 cutaneous electrodes is embedded evenly in a latex mat. The mat can be firmly attached to the abdominal surface by drawing a vacuum between the matrix and the stomach. Twenty-five high-amplification filter/amplifiers provide a high signal-to-noise ratio and flat amplitude response for a signal between 0.02 and 0.12 Hz (1.2-7.2 cpm). The computer program provides waveform and frequency analysis for any chosen channel and mapping analyses for all 25 channels. A two-dimensional propagation exploration program was also developed. Using four different mapping analysis program subroutines, the optimal points for analyzing the EGG signals can be reliably found and variability of these locations can be observed easily. Results show differences in the EGG mappings of normal and abnormal subjects.

Detection and deletion of motion artifacts in electrogastrogram using feature analysis and neural networks

Electrogastrogram is a surface measurement of gastric myoelectrical activity, and electrogastrography has been an attractive method for physiological and pathophysiological studies of the stomach due to its noninvasive nature. Motion artifacts, however, ruin the electrogastrogram (EGG), and make the analysis very difficult and sometimes even impossible. They must be eliminated from EGG signals before analysis. Up to now, this can only be done by visual inspection, which is not only time-consuming but also subjective. In this study, a method using feature analysis and neural networks has been developed to realize automatic detection and elimination of the motion artifacts in EGG recordings by computer. Experiments were conducted to investigate the characteristics of different motion artifacts. Useful features were extracted, and different combinations of the features used as the input of the neural network were compared to obtain the optimal performance for the detection of motion artifacts using the artificial neural network.

High-pass filtering of the electrogastrogram

The recording and processing of an electrogastrogram require adequate band-pass filtering, to suppress unwanted artefacts but preserve the original signal waveform. High-pass filtering of various types, of different time constants tau, filter order, analogue and digital implementation, have been used to obtain higher baseline stability and faster signal recovery after strong artefacts. Special attention should be given to possible signal amplitude and phase distortions due to high-pass filtering, which can strongly influence accurate amplitude measurements or studies of signal propagation from multichannel recordings. Synthesised and original signals are used to demonstrate the effect of high-pass filtering. The use of a first-order filter with tau = 5 s is recommended for EGG studies if not especially directed to investigation of bradygastria. In the opposite case, tau = 15 s should be used, and with backward filtering a full restoration of the original signal can be obtained. The same is valid for recording the electrical activity of the colon. Lower time constants (tau = 5 s or less) can be applied to acquire signals from the small intestines. A radical solution is the use of a DC amplifier with controllable subtraction of the DC component.

Gastric physiology and function: effects of fruit juices

The stomach stores food and starts digesting protein and fat. Lipids, sugars, certain amino acids, and nutrients of high osmolality trigger sensory mechanisms from the intestine which inhibit gastric emptying. Food rich in carbohydrates leaves the stomach slower than protein-rich food, and emptying is slowest after a meal containing lipid. For carbohydrate beverages, the gastric emptying rate is primarily determined by the volume, caloric content, and osmolality of fluid ingested. Gastric emptying rates vary among isocaloric beverages of different type (e.g., sucrose, fructose, galactose) or forms (e.g., maltodextrins, starches) of carbohydrate. For instance, gastric emptying is faster for a fructose solution compared with isocaloric glucose and galactose solutions. A maltodextrin or a sucrose solution empties faster than a glucose solution. This is possibly due to the greater inhibitory feedback associated with the introduction of glucose in the duodenum. In addition, fruit juices contain soluble fibers which further modulate the gastric emptying. Noninvasive methods to study gastric emptying have recently been developed. The pattern of the myoelectric activity of the gastric contraction and the effect of meals on this pattern can now be recorded by cutaneous electrodes. In healthy children ingesting different juices, the myoelectric pattern of the stomach (indicator of the gastric emptying) correlates with the carbohydrate absorption (measured by breath hydrogen excretion). Fast gastric emptying was associated with greater production of breath hydrogen. The malabsorption of juice carbohydrates may in part be related to their effect on gastric motility.

24-hour ambulatory electrogastrography in healthy volunteers

BACKGROUND

Development of electrogastrography, the recording of gastric electric rhythm from cutaneous electrodes, for clinical purposes has been hampered by methodologic problems and the lack of an ambulatory technique. We have evaluated a newly developed system for ambulatory electrogastrography.

METHODS

24-Hour recordings were obtained from 30 healthy volunteers. We used digital filtering, a Hamming window, and spectral analysis to determine the dominant frequency of successive 256-sec segments of data.

RESULTS

Low-frequency noise disturbed the primary signal. After secondary filtering a stable normogastric (2-4 cpm) rhythm was present during a median of 49% (range, 34-79%) of the recording time. The mean frequency of gastric electric activity varied from 2.92 +/- 0.15 cpm (mean +/- SD) at mid-day to 2.72 +/- 0.13 cpm in the late night.

CONCLUSIONS

Ambulatory recording of electrogastrography needs technical improvement. The electrogastrogram shows a circadian variation in frequency.

Systemic and central effects of morphine on gastroduodenal motility

Gastrointestinal side effects still constitute a major drawback in both acute and chronic use of opioids. The exact mechanism behind the gastrointestinal effects is not known, but experimental studies indicate both central and peripheral actions. In an attempt to clarify to what extent the systemic effects of morphine after epidural administration contribute to the action on gastrointestinal motility, a study aiming to resemble the situation with epidural morphine was designed. Twenty healthy male volunteers were randomly allocated to two groups. Group one (n = 10) received intrathecal (0.4 mg) and intramuscular (4 mg) morphine (IT-IM-group). Group two (n = 10) received intrathecal (0.4 mg) morphine and i.m. saline (IT-group). Gastroduodenal activity was assessed by gastric emptying, manometry and electrogastrography. The plasma and urine concentrations of morphine and its inactive metabolite morphine-3-and active metabolite morphine-6-glucuronide were also determined. During the fasted state the gastrointestinal activity is characterised by a cyclic pattern with a duration of 80-120 min in the duodenum comprising three different phases with intense activity during Phase III. This pattern was seen in all volunteers. After the intrathecal administration the Phase III activity occurred significantly earlier in the IT-IM group (median 31 min; IR 34 min) compared to IT group (82 min; 37 min) (P < 0.01). The number of Phase IIIs was higher in the IT-IM group during the first 4 h after the morphine administration, compared to the IT group. However, after 6 h, there was no difference between the groups. The propagation velocity of Phase III decreased significantly in both groups (P < 0.001), but there was no difference between the groups. Tachygastria increased significantly with time in both groups. The acetaminophen absorption test showed that the area under the concentration curve (120 min) was significantly smaller in the IT-IM group compared to the IT group (P < 0.05). There were no measurable plasma concentrations of morphine or the glucoronidated metabolites M3G and M6G in the group that only received intrathecal morphine. This study showed that intrathecal morphine (0.4 mg) influenced gastroduodenal motility and that intramuscular morphine (4 mg) gave additional effects. These results might be applicable to the epidural situation and are indirect evidence that the gastroduodenal effects of epidural morphine are caused by both central and systemic effects of morphine.

Time-frequency representation of the electrogastrogram--application of the exponential distribution

The aim of this paper was to examine the applicability of the exponential distribution for the time-frequency representation of the electrogastrogram (EGG). The EGG is a noninvasive measurement of the electrical activity of the stomach by placing electrodes on the abdominal skin. Quantitative analysis of the EGG has relied on spectral methods. The normal frequency of the EGG in humans is 3 cycles/min. Electrical dysrhythmia observed in the EGG is associated with motor disorders of the stomach. The exponential distribution was applied in this work for the estimation of EGG frequency and the detection of dysrhythmia in the EGG. A series of computer simulations was conducted, demonstrating the reliability of the exponential distribution in the analysis of nonstationary electrical signals of the stomach. Applications of the exponential distribution in the spectral analysis of typical EGG's were presented. The results showed that there is a great potential for the use of the exponential distribution in EGG analysis.