Marco W. Mundt

Low antroduodenal pressure gradients are responsible for gastric emptying of a low‐caloric liquid meal in humans

The motor mechanisms responsible for transpyloric flow of gastric contents are still poorly understood. The aim of our study was to investigate the relationship between luminal pressures and gastric wall motion and between gastroduodenal pressure gradients and pressure waves, and ante‐ and retro‐grade transpyloric flow. In eight healthy volunteers, intraluminal pressures were recorded from the antrum and proximal duodenum. Transpyloric flow was monitored simultaneously using duplex ultrasonography, before, during and after ingestion of 300 mL meat soup. Transpyloric emptying occurred as sequences of alternating periods of emptying–reflux–emptying. Approximately one‐third of the sequences were not associated with peristalsis. The antroduodenal pressure gradients were significantly lower during nonperistaltic‐related emptying than during peristaltic‐related emptying (0.15 (0–0.3) kPa, and 1.7 (0.2–2.0) kPa, respectively [mean ± (range)], P < 0.005). The duration of emptying episodes not associated with peristalsis were significantly longer than those associated with peristalsis at (6.5 (3–8.7) s and 4.4 (2–6) s, respectively, P=0.059). Manometry detected only 56% of the antral contractions seen on ultrasound. We concluded that gastric emptying of a low‐calorie liquid meal occurs both during peristaltic and nonperistaltic antral activity. In spite of lower antroduodenal pressure gradients, the emptying episodes were longer for nonperistaltic emptying, which is likely to be caused by low pyloric resistance. Considerable flow seems to occur without peristalsis during gastric emptying of a low‐calorie, liquid meal in humans.

Analysis of surface geometry of the human stomach using real-time 3-D ultrasonography in vivo.

Abstract  The objective of this study was to develop an analytical method to describe the three‐dimensional (3‐D) geometry of the gastric antrum, gastric fundus and the whole stomach. The Fourier series method was used to simulate the organ surface geometry obtained from a 3‐D ultrasound system. Data generated from eight antrums and three whole stomachs, at pressures of approximately 7 cmH2O, were used for lumen curvature calculations. The principal curvatures spatial distributions were non‐homogeneous in the gastric antrum, gastric fundus and the stomach due to their complex geometry. The maximum longitudinal principal curvature in the antrum, fundus and total stomach were, respectively, 0.460 ± 0.066, 0.583 ± 0.087 and 1.123 ± 0.328, whereas the maximum circumferential curvature were 1.192 ± 0.090, 3.649 ± 1.574 and 8.444 ± 3.424, respectively. The present study provides an analytical tool for characterizing the complex 3‐D geometry of an organ‐like the human stomach reconstructed by clinical imaging modalities. Providing an average tension for the stomach does not reflect the large variation in tension throughout the stomach wall.

Relationships between gastric accommodation and gastrointestinal sensations in healthy volunteers. A study using the barostat technique and two- and three-dimensional ultrasonography.

The origin of postprandial gastrointestinal sensations and their relation to gastric accommodation remain unclear. Our aim was to investigate the relation between antral and fundal accommodation and sensations. (A) In eight healthy volunteers fundus accommodation was measured using a barostat after a 200-ml (300-kcal) liquid nutrient. Antral area (AA) was measured using ultrasound. Data on bag volumes, AA, and sensations were assessed. (B) In another eigth healthy volunteers gastric volume was measured after a 500-ml (300-kcal) liquid nutrient using 2-D/3-D ultrasound. Sensations were scored using VAS. Distal and proximal volumes were calculated from 3-D datasets. (A) Fullness was correlated with AA (r = 0.48, P = 0.002). Fullness and bag volume were not correlated. (B) Fullness was correlated with AA (r = 0.77, P < 0.001) and distal volume (r = 0.75, P < 0.001). Proximal volume was not correlated with fullness (r = 0.10, P = NS). We conclude that fullness is related to antral volume and area rather than proximal volume. The gastric antrum may play a key role in normal appetite regulation.

Gastric Emptying of a Solid Meal Starts during Meal Ingestion: Combined Study Using 13C-Octanoic Acid Breath Test and Doppler Ultrasonography

Scintigraphy and the C-13-octanoic acid breath test are both applied to assess gastric emptying. Using the C-13-octanoic acid breath test, excretion curves show C-13 excretion immediately after ingestion of a solid egg meal, in contrast with scintigraphy where gastric emptying is observed after a lag phase. The aim of our study was to investigate whether transpyloric flow occurs during and directly after meal ingestion. Therefore, transpyloric flow was measured during and after ingestion of an egg meal labeled with C-13-octanoic acid, using Doppler ultrasonography. The breath test was performed simultaneously, with samples taken at regular intervals. The first emptying episode was observed 6.9 (3.9-16.2) min after start of meal ingestion. A significant relation between recovery of C-13 and total duration of gastric emptying during the first 20 min was observed (partial correlation coefficient r = 0.80, p <0.001). In conclusion, transpyloric flow starts during ingestion of a solid egg meal and results in detectable excretion of C-13. Copyright (C) 2004 S. Karger AG, Basel.Scintigraphy and the 13C-octanoic acid breath test are both applied to assess gastric emptying. Using the 13C-octanoic acid breath test, excretion curves show 13C excretion immediately after ingestion of a solid egg meal, in contrast with scintigraphy where gastric emptying is observed after a lag phase. The aim of our study was to investigate whether transpyloric flow occurs during and directly after meal ingestion. Therefore, transpyloric flow was measured during and after ingestion of an egg meal labeled with 13C-octanoic acid, using Doppler ultrasonography. The breath test was performed simultaneously, with samples taken at regular intervals. The first emptying episode was observed 6.9 (3.9–16.2) min after start of meal ingestion. A significant relation between recovery of 13C and total duration of gastric emptying during the first 20 min was observed (partial correlation coefficient r = 0.80, p < 0.001). In conclusion, transpyloric flow starts during ingestion of a solid egg meal and results in detectable excretion of 13C.

Fundal dysaccommodation in functional dyspepsia: head-to-head comparison between the barostat and three-dimensional ultrasonographic technique

Background: Recently, non-invasive techniques such as 3 dimensional ultrasonography (3DUS) have been developed to assess gastric wall characteristics and to investigate their relationship with upper gastrointestinal sensations. To date, no head-to-head comparison has been carried out between the barostat and the 3DUS technique. Aim: To compare barostat and 3DUS and to investigate the relationship between gastric volumes and sensations in patients with functional dyspepsia and in healthy subjects. Patients and methods: Gastric accommodation was studied in 15 patients with functional dyspepsia and in 15 healthy subjects after ingestion of a liquid nutrient (300 kcal) using barostat and 3DUS in random order for 60 min. Proximal gastric relaxation was measured using barostat and gastric volume using 3DUS. Change in gastric volume, acquired by 3DUS, was expressed as total gastric volume/proximal volume ratio (TGV/PV) and compared with changes in barostat volume (fundal accommodation). Results: Patients with functional dyspepsia showed a smaller change in proximal gastric volume than healthy subjects using barostat (mean (SD) 82 (61) v 205 (79) ml, p<0.01) and 3DUS (118 (41) v 199 (39) ml, p<0.01). Dysaccommodation of the proximal stomach was observed in 7 of 15 (46%) patients using the barostat technique. 10 of 15 (67%) patients were found to have an abnormal change in proximal gastric volume using TGV/PV ratio. At 5 min postprandially, fullness was related to the change in distal gastric volume (r = 0.51, p = 0.006) in the 3DUS study, whereas no relationship was observed in the barostat study. Conclusion: 3DUS is a feasible non-invasive technique to measure gastric volumes and shows a distinct overlap with barostat data in healthy subjects and patients with functional dyspepsia. Fullness relates to distal gastric volumes when assessed by non-invasive 3DUS.

Gastrointestinal motility testing

Gastrointestinal motility and the effects on luminal contents that are brought about by it can be studied in several ways. In clinical practice, manometry remains one of the most important investigational techniques, in particular for oesophageal and anorectal disorders. Radiographic examination of bolus transit through the gastrointestinal tract also continues to be a valuable tool. Scintigraphy still is the gold standard for assessment of gastric emptying, but (13)(C) breath tests are an alternative. Many other techniques are used mainly in the context of scientific research but some of these may become incorporated in the diagnostic armamentarium.

Partial Gastric Volumes and Upper Abdominal Sensations in Functional Dyspeptic and GERD Patients: A 3D Ultrasonographic Study

OBJECTIVES:The aim of the study was to evaluate the change in proximal and distal gastric volumes after ingestion of a nutrient drink and its relationship to upper abdominal sensations using three-dimensional ultrasonography.METHODS:Fifty FD patients, 20 GERD patients patients and 35 healthy controls participated. Partial gastric volumes and sensations were assessed while fasting and after ingestion of a nutrient drink (500 mL, 300 kcal). Division of partial gastric volumes by total gastric volume was used to calculate proximal and distal gastric volume ratios.RESULTS:The proximal gastric volume ratio was smaller in FD patients and larger in GERD patients compared to controls (p < 0.001 and p = 0.008, respectively). FD patients with impaired proximal relaxation (46%) had a larger increase in distal gastric volume (p = 0.008) and higher fullness sensations (p = 0.027) compared to FD patients with normal proximal relaxation. Fullness was related to distal gastric volume in both GERD patients and healthy controls (r = 0.761, p < 0.001 and r = 0.674, p = 0.001, respectively). In FD patients this relationship was not observed.CONCLUSIONS:Impaired proximal gastric volume change after ingestion of a nutrient drink is associated with a larger distal gastric volume and increased fullness. In health and in GERD patients, the distal stomach is important in the regulation of fullness. However, in FD patients with normal or altered gastric volume distribution, this relationship is disturbed, implying that other causes are involved in the excessive generation of fullness.

Fecal immunochemical testing results and characteristics of colonic lesions

BACKGROUND AND STUDY AIMS Fecal immunochemical tests (FIT) are used to detect blood in feces, which might indicate the presence of colorectal neoplasia. The aim of this study was to investigate whether FIT results vary depending on the characteristics of colonic lesions. PATIENTS AND METHODS This was a retrospective analysis of lesions detected in a cohort of asymptomatic individuals (aged 50 - 75 years) who were invited to participate in a FIT-based screening pilot in The Netherlands. The mean FIT result was compared across subgroups of individuals defined by histopathology of the most advanced lesion detected. In addition, the results were compared with data from a primary colonoscopy screening trial, in which participants also completed a FIT. RESULTS In three rounds of FIT-based screening, a total of 877 FIT-positive individuals underwent colonoscopy. Higher mean FIT results (hemoglobin [Hb]/g feces) were observed in individuals with carcinomas (199 μg Hb/g) and advanced adenomas (87 μg Hb/g) compared with participants with nonadvanced adenomas (50 μg Hb/g) or those with serrated lesions (46 μg Hb/g) (P < 0.001). In the primary colonoscopy trial, 1256 participants completed a FIT test and underwent colonoscopy. The number of participants with nonadvanced adenomas as the most advanced lesion was comparable between this group and the FIT-based screening group (20 % vs. 22 %). CONCLUSION In FIT-based screening, the mean FIT results varied depending on the characteristics of the most advanced colonic lesion. The proportion of participants with a nonadvanced adenoma as the most advanced lesion was similar in the FIT-based screening group and in the primary colonoscopy screening group, suggesting that these lesions are coincidental findings rather than FIT-detected findings. CLINICAL TRIAL REGISTRATION www.trialregister.nl number NTR2755.

The 5-HT4 antagonist R216073 does not affect gastric motor and sensory function in patients with functional dyspepsia

Background  Serotonin and the 5‐HT4 receptor play an important role in gastrointestinal motor and sensory functions. While 5‐HT4 agonists are known for their prokinetics properties, the effect of 5‐HT4 antagonists on upper gastrointestinal functions is largely unknown.

Impact of transient elastography on clinical decision-making in patients with chronic viral hepatitis

Abstract Objective. Transient elastography is a noninvasive tool to quantify liver fibrosis by liver stiffness measurements (LSMs). Previous studies have extensively evaluated the accuracy of LSMs compared to liver biopsy. In this retrospective study we explore potential impact of LSMs on clinical decisions in chronic viral hepatitis. Material and methods. LSM-based medical advice whether to start antiviral treatment and/or surveillance for hepatocellular carcinoma (HCC) and clinical follow-up after LSMs were analyzed in 349 patients. Results. In 20% of 184 hepatitis B virus (HBV)-infected patients and 38% of 165 hepatitis C virus (HCV)-infected patients, significant fibrosis (≥F2) was detected. In 5% (n = 7) of the 129 untreated HBV patients and in 12% (n = 19) of the HCV-infected patients, antiviral treatment was recommended solely based on LSMs. Advice for surveillance for HCC was in 40 patients based solely on LSMs (11% of all patients). Furthermore, 95% of 19 non-viremic HCV-patients (after spontaneous clearance or sustained viral response) could be discharged due to favorable LSMs (≤F2). Medical advice was followed by the treating physician in the majority of cases. However, in only 47% of 51 HCV-infected patients with advice to start treatment, this was followed in clinical practice. Conclusions. Transient elastography has a major impact on clinical practice, both as an indication to start or postpone antiviral treatment, to start surveillance for HCC, and to discharge HCV patients from follow-up after viral clearance and favorable LSMs. Medical advice to start antiviral treatment is followed in the large majority of HBV patients, but in only half of HCV patients.