Gastric motor and sensory function

Electrogastrography measurement systems and analysis methods used in clinical practice and research: comprehensive review

Electrogastrography (EGG) is a non-invasive method with high diagnostic potential for the prevention of gastroenterological pathologies in clinical practice. In this study, a review of the measurement systems, procedures, and methods of analysis used in electrogastrography is presented. A critical review of historical and current literature is conducted, focusing on electrode placement, measurement apparatus, measurement procedures, and time-frequency domain methods of filtration and analysis of the non-invasively measured electrical activity of the stomach. As a result, 129 relevant articles with primary aim on experimental diet were reviewed in this study. Scopus, PubMed, and Web of Science databases were used to search for articles in English language, according to the specific query and using the PRISMA method. The research topic of electrogastrography has been continuously growing in popularity since the first measurement by professor Alvarez 100 years ago, and there are many researchers and companies interested in EGG nowadays. Measurement apparatus and procedures are still being developed in both commercial and research settings. There are plenty variable electrode layouts, ranging from minimal numbers of electrodes for ambulatory measurements to very high numbers of electrodes for spatial measurements. Most authors used in their research anatomically approximated layout with two++ active electrodes in bipolar connection and commercial electrogastrograph with sampling rate of 2 or 4 Hz. Test subjects were usually healthy adults and diet was controlled. However, evaluation methods are being developed at a slower pace, and usually the signals are classified only based on dominant frequency. The main review contributions include the overview of spectrum of measurement systems and procedures for electrogastrography developed by many authors, but a firm medical standard has not yet been defined. Therefore, it is not possible to use this method in clinical practice for objective diagnosis.

Systematic Review Registration

https://www.prisma-statement.org/.

Postprandial effect of gastrointestinal hormones and gastric activity in patients with irritable bowel syndrome

Altered gut regulation, including motor and secretory mechanisms, is characteristic of irritable bowel syndrome (IBS). The severity of postprandial symptoms in IBS patients is associated with discomfort and pain; gas-related symptoms such as bloating and abdominal distension; and abnormal colonic motility. The aim of this study was to assess the postprandial response, i.e., gut peptide secretion and gastric myoelectric activity, in patients with constipation-predominant IBS. The study was conducted on 42 IBS patients (14 males, 28 females, mean age 45.1 ± 15.3 years) and 42 healthy participants (16 males, 26 females, mean age 41.1 ± 8.7 years). The study assessed plasma gut peptide levels (gastrin, CCK-Cholecystokinin, VIP-Vasoactive Intestinal Peptide, ghrelin, insulin) and gastric myoelectric activity obtained from electrogastrography (EGG) in the preprandial and postprandial period (meal-oral nutritional supplement 300 kcal/300 ml). Mean preprandial gastrin and insulin levels were significantly elevated in IBS patients compared to the control group (gastrin: 72.27 ± 26.89 vs. 12.27 ± 4.91 pg/ml; p < 0.00001 and insulin: 15.31 ± 12.92 vs. 8.04 ± 3.21 IU/ml; p = 0.0001), while VIP and ghrelin levels were decreased in IBS patients (VIP: 6.69 ± 4.68 vs. 27.26 ± 21.51 ng/ml; p = 0.0001 and ghrelin: 176.01 ± 88.47 vs. 250.24 ± 84.55 pg/ml; p < 0.0001). A nonsignificant change in the CCK level was observed. IBS patients showed significant changes in postprandial hormone levels compared to the preprandial state-specifically, there were increases in gastrin (p = 0.000), CCK (p < 0.0001), VIP (p < 0.0001), ghrelin (p = 0.000) and insulin (p < 0.0001). Patients with IBS showed reduced preprandial and postprandial normogastria (59.8 ± 22.0 vs. 66.3 ± 20.2%) compared to control values (83.19 ± 16.7%; p < 0.0001 vs. 86.1 ± 9.4%; p < 0.0001). In response to the meal, we did not observe an increase in the percentage of normogastria or the average percentage slow-wave coupling (APSWC) in IBS patients. The postprandial to preprandial power ratio (PR) indicates alterations in gastric contractions; in controls, PR = 2.7, whereas in IBS patients, PR = 1.7, which was significantly lower (p = 0.00009). This ratio reflects a decrease in gastric contractility. Disturbances in the postprandial concentration of gut peptides (gastrin, insulin and ghrelin) in plasma may contribute to abnormal gastric function and consequently intestinal motility, which are manifested in the intensification of clinical symptoms, such as visceral hypersensitivity or irregular bowel movements in IBS patients.

Robust Methods to Detect Abnormal Initiation in the Gastric Slow Wave from Cutaneous Recordings

Upper gastrointestinal (GI) disorders are highly prevalent, with gastroparesis (GP) and functional dyspepsia (FD) affecting 3% and 10% of the US population, respectively. Despite overlapping symptoms, differing etiologies of GP and FD have distinct optimal treatments, thus making their management a challenge. One such cause, that of gastric slow wave abnormalities, affects the electromechanical coordination of pacemaker cells and smooth muscle cells in propelling food through the GI tract. Abnormalities in gastric slow wave initiation location and propagation patterns can be treated with novel pacing technologies but are challenging to identify with traditional spectral analyses from cutaneous recordings due to their occurrence at the normal slow wave frequency. This work advances our previous work in developing a 3D convolutional neural network to process multi-electrode cutaneous recordings and successfully classify, in silico, normal versus abnormal slow wave location and propagation patterns. Here, we use transfer learning to build a method that is robust to heterogeneity in both the location of the abnormal initiation on the stomach surface as well as the recording start times with respect to slow wave cycles. We find that by starting with training lowest-complexity models and building complexity in training sets, transfer learning one model to the next, the final network exhibits, on average, 80% classification accuracy in all but the most challenging spatial abnormality location, and below 5% Type-I error probabilities across all locations.

Is gastroparesis a gastric disease?

BACKGROUND

Gastroparesis is a digestive syndrome characterized by delayed gastric emptying (GE) and by symptoms that are suggestive of gastroduodenal motor disorders. There are three grades of gastroparesis of increasing severity: (a) mild gastroparesis; (b) compensated gastroparesis; and (c) gastric failure. GE abnormalities are partially related to symptom type and severity, and other mechanisms may be involved.

AIM

To investigate enteric dysmotility (ED) in patients with suspected gastroparesis.

METHODS

Patients with symptoms suggestive of gastroparesis were consecutively included in the study and underwent a ¹³ C-octanoic acid GE breath test and small bowel manometry (SBM). Clinical features were recorded using predefined, validated questionnaires at entry.

KEY RESULTS

The study enrolled 88 patients (71 women; mean age: 37.8 ± 14.3 years). Gastric emptying was delayed in 25 patients (28.4%), and 70 patients (79.5%) presented small bowel motor abnormalities including bursts, abnormal activity fronts, inability to respond to meal ingestion, and hypocontractility. Gastric emptying was delayed in 24 of the 70 patients with ED (34.3% vs 5.5% of patients with normal SBM). Enteric dysmotility was detected in 24 of 25 patients (96%) with delayed GE. Patients with and without delayed GE showed similar moderate/severe gastroparesis manifestations, but patients with ED significantly more often had moderate/severe gastroparesis manifestations than patients with normal SBM (grade 1:14% vs 39%, grade 2:62% vs 56%, grade 3:24% vs 5%, respectively).

CONCLUSIONS AND INFERENCES

Enteric dysmotility was more frequent than delayed GE in patients with symptoms suggestive of gastroparesis. Gastroparesis severity was associated with small bowel motor abnormalities but not with delayed GE.

Gastroparesis and Functional Dyspepsia: A Blurring Distinction of Pathophysiology and Treatment

Gastroparesis and functional dyspepsia are 2 of the most common gastric neuromuscular disorders. These disorders are usually confused, having both similarities and differences. The pathophysiology of these disorders involves abnormal gastric motility, visceral hypersensitivity, mucosal inflammation, and various cellular changes. Both disorders have similar symptoms such as epigastric pain or discomfort, early satiety, and bloating. If patients suspected of having either gastroparesis or functional dyspepsia present with upper gastrointestinal symptoms, they should undergo upper endoscopy to exclude an alternative organic cause. Although the gastric emptying rate is frequently assessed during the clinical workup of patients with gastroparesis or functional dyspepsia, the correlation between gastric emptying and the symptoms is generally poor. Once the diagnosis of gastroparesis or functional dyspepsia is made, treatment should focus on the predominant symptom. Recently, various treatment modalities have been developed and validated. Prokinetic agents are generally used as treatment for both gastroparesis and functional dyspepsia. Acid-suppressive therapy, Helicobacter pylori eradication, and use of drugs that enhance gastric accommodation are employed for functional dyspepsia. Psychoactive drugs are also effective in symptom control. For gastroparesis, antiemetic agents, ghrelin receptor agonists, and serotonergic agents are used aside from prokinetic agents. Acupuncture and gastric electrical stimulation can be attempted. In severe cases, endoscopic and surgical interventions are considered for symptom control.

Assessment of orocecal transit time by breath hydrogen test in two subtypes of functional dyspepsia

AIM: To explore the orocecal transit time (OCTT) in two subtypes of functional dyspepsia, and to study the effects of gender, age and body mass index (BMI) on OCTT.

METHODS: Twenty-five postprandial distress syndrome (PDS) patients, twenty-two epigastric pain syndrome (EPS) patients and twenty healthy volunteers were used. All of them received the breath hydrogen test, and the OCTT was recorded.

RESULTS: A significant difference in OCTT was detected between PDS patients and healthy volunteers, but not between EPS patients and healthy volunteers. Gender appeared not to influence OCTT in all three groups. There was a positive correlation between age and OCTT in healthy volunteers, but not in PDS patients or EPS patients. BMI-related differences in OCTT were noted in healthy volunteers, but not in PDS patients or EPS patients.

CONCLUSION: In PDS patients, intestinal transit function is impaired. Age and BMI appear to influence OCTT in healthy volunteers, but not in PDS patients or EPS patients.

Gastroesophageal reflux in critically ill patients

Gastroesophageal reflux (GER) is a common occurrence in critically ill, mechanically ventilated patients. Reflux can lead to pulmonary aspiration of gastric contents and subsequent pneumonia. Several characteristics of patients, interventions provided in the intensive care unit setting, and factors associated with feeding increase a patient's risk for reflux. Critical care nurses and clinical nurse specialists can identify patients at highest risk for GER by utilizing the patient's history, reviewing the medications, and assessing the current status to provide interventions to reduce the risk of GER and its sequelae of aspiration pneumonia. This article reviews the physiology of GER, risk factors, and interventions to decrease GER in the critically ill patient.

Electrogastrography in adults and children: the strength, pitfalls, and clinical significance of the cutaneous recording of the gastric electrical activity

Cutaneous electrogastrography (EGG) is a non-invasive technique to record gastric myoelectrical activity from the abdominal surface. Although the recent rapid increase in the development of electrocardiography, EGG still suffers from several limitations. Currently, computer analysis of EGG provides few reliable parameters, such as frequency and the percentage of normal and altered slow wave activity (bradygastria and tachygastria). New EGG hardware and software, along with an appropriate arrangement of abdominal electrodes, could detect the coupling of the gastric slow wave from the EGG. At present, EGG does not diagnose a specific disease, but it puts in evidence stomach motor dysfunctions in different pathological conditions as gastroparesis and functional dyspepsia. Despite the current pitfalls of EGG, a multitasking diagnostic protocol could involve the EGG and the (13)C-breath testing for the evaluation of the gastric emptying time-along with validated gastrointestinal questionnaires and biochemical evaluations of the main gastrointestinal peptides-to identify dyspeptic subgroups. The present review tries to report the state of the art about the pathophysiological background of the gastric electrical activity, the recording and processing methodology of the EGG with particular attention to multichannel recording, and the possible clinical application of the EGG in adult and children.

Dyspepsia: organic versus functional

Dyspepsia is the medical term for difficult digestion. It consists of various symptoms in the upper abdomen, such as fullness, discomfort, early satiation, bloating, heartburn, belching, nausea, vomiting, or pain. The prevalence of dyspepsia in the western world is approximately 20% to 25%. Dyspepsia can be divided into 2 main categories: "organic" and "functional dyspepsia" (FD). Organic causes of dyspepsia are peptic ulcer, gastroesophageal reflux disease, gastric or esophageal cancer, pancreatic or biliary disorders, intolerance to food or drugs, and other infectious or systemic diseases. Pathophysiological mechanisms underlying FD are delayed gastric emptying, impaired gastric accommodation to a meal, hypersensitivity to gastric distension, altered duodenal sensitivity to lipids or acids, altered antroduodenojenunal motility and gastric electrical rhythm, unsuppressed postprandial phasic contractility in the proximal stomach, and autonomic nervous system-central nervous system dysregulation. Pathogenetic factors in FD are genetic predisposition, infection from Helicobacter pylori or other organisms, inflammation, and psychosocial factors. Diagnostic evaluation of dyspepsia includes upper gastrointestinal endoscopy, abdominal ultrasonography, gastric emptying testing (scintigraphy, breath test, ultrasonography, or magnetic resonance imaging), and gastric accommodation evaluation (magnetic resonance imaging, ultrasound, single-photon emission computed tomography, and barostat). Antroduodenal manometry can be used for the assessment of the myoelectrical activity of the stomach, whereas sensory function can be evaluated with the barostat, tensostat, and satiety test. Management of FD includes general measures, acid-suppressive drugs, eradication of H. pylori, prokinetic agents, fundus-relaxing drugs, antidepressants, and psychological interventions. This review presents an update on the diagnosis of patients presenting with dyspepsia, with an emphasis on the pathophysiological and pathogenetic mechanisms of FD and the differential diagnosis with organic causes of dyspepsia. The management of uninvestigated and FD, as well as the established and new pharmaceutical agents, is also discussed.

Postoperative problems 2011: fundoplication and obesity surgery

Although the surgical treatment of both GERD and obesity is very successful, these procedures have a significant impact on the physiology and function of the proximal GI tract. With the increasing prevalence of both GERD and obesity, more and more patients present at the motility outpatient clinic with symptoms related to surgical interventions for these medical problems. In this review, we describe the main complications following antireflux surgery: dysphagia, gas bloat syndrome, recurrent (persistent) GERD symptoms, and dyspeptic symptoms. The most common motility-related complications of obesity surgery are dumping syndrome and esophageal dysmotility.

Leukotriene-induced contraction is mediated by cysteinyl leukotriene receptor CysLT1 in guinea pig fundus but by CysLT1 and CysLT2 in antrum

AIMS

Leukotriene D(4) (LTD(4)) causes contraction of the stomach through unclear receptors. The aim of the present study is to characterize the cysteinyl leukotriene receptor (CysLT) mediating leukotriene-induced muscle contraction in the stomach.

MAIN METHODS

We measured contraction of gastric muscle strips isolated from the guinea pig fundus and antrum caused by cysteinyl leukotrienes, including LTC(4), LTD(4) and LTE(4), as well as the dihydroxy leukotriene LTB(4) in vitro.

KEY FINDINGS

In both fundic and antral muscle strips, LTC(4) and LTD(4) caused marked whereas LTE(4) caused moderate, concentration-dependent contractions. In contrast, LTB(4) caused only small contraction. The relative potencies for cysteinyl leukotrienes to cause contraction in both fundus and antrum were LTC(4)=LTD(4)>LTE(4). The LTD(4)-induced contraction was not affected by tetrodotoxin or atropine, suggesting that the action is not neurally mediated. The LTD(4)-induced contraction in the fundus was almost abolished by the CysLT(1) selective antagonist montelukast. In contrast, the LTD(4)-induced contraction in the antrum was only partially inhibited by montelukast or the dual CysLT(1) and CysLT(2) antagonist BAY u9773. This antral contraction was almost abolished by the combination of montelukast and BAY u9773, indicating enhancement of inhibition.

SIGNIFICANCE

The results of the present study demonstrate that cysteinyl leukotrienes LTC(4), LTD(4) and LTE(4) cause moderate to marked whereas the dihydroxy leukotriene LTB(4) causes small muscle contraction in the stomach in vitro. The leukotriene-induced contraction is mediated by CysLT(1) in fundus but by CysLT(1) and CysLT(2) in antrum.

The dysfunctional gut

After many decades debating whether the clinical manifestations of patients with functional digestive symptoms originate "in their minds" or "in their guts," arguments remain strong on both sides of the controversy. However, advances in understanding of gut physiology and pathophysiology, and persuasive evidence on the bidirectionality of the regulatory traffic between the enteric and central nervous systems, are helping to characterize clinical situations in which we can legitimately speak of gut dysfunction, as opposed to others where symptoms are not associated with apparent or detectable gut disturbances and may truly represent somatization of an affective disorder. In this review, we describe available clinically applicable technology, albeit in specialized clinical research units, that may be used to discern whether or not challenging patients have gut sensory or motor disturbances. The practical yield of applying such methods to diagnostic investigation may be substantial, because it establishes a plausible mechanism of disease that may be used in patient management and patient persuasion, to remove uncertainties and to prevent futile repetition of conventional diagnostic tests. By evolving from symptom analysis to mechanism-based diagnosis, our gastroenterology community may progress toward the goal of delivering the full diagnostic spectrum from altered morphology to disturbed function.