Unraveling functional abdominal bloating and distension: the role of thoraco-abdominal accommodation and a physical sign to aid its detection

Bloating and distension are common complaints in patients with irritable bowel syndrome of which the cause has remained elusive, although it has been shown that the obvious explanation of excessive gas is unlikely. The recent application of technologies such as the gas challenge technique, abdominal inductance plethysmography, CT scanning, as well as electromyography of the diaphragm and anterior abdominal wall, have allowed the situation to be slowly unraveled. It is now seems probable that the pathophysiology of bloating and distension are subtly different with the former having a sensory component whereas mechanical factors, such as disordered abdominal accommodation, contribute more to the latter.     

Elicitation of transient lower oesophageal sphincter relaxations in response to gastric distension and meal ingestion

The aim of this study was to compare the effect of graded gastric barostat distension and meal-induced fundic relaxation on the elicitation of transient lower oesophageal sphincter relaxation (TLOSR). In 15 healthy subjects, stepwise fundic distension and oesophageal manometry were performed simultaneously. Next, the effect of meal ingestion on proximal stomach volume and lower oesophageal sphincter function was studied. During stepwise barostat distension of the proximal stomach, a significant linear correlation between intragastric pressure (r = 0.91; P < 0.01) and the TLOSR rate during inflation and subsequent deflation (r = 0.96; P < 0.01) was found. A similar relationship was found for volume. In addition, after meal ingestion, the TLOSR rate increased significantly from 1.40 +/- 3 to 5.4 +/- 1.5 h-1 (P < 0.01) and 5.2 +/- 1.7 h-1 (P < 0.01), respectively, during the first and second 30-min postprandially. However, at similar calculated intragastric volumes, barostat distension led to a significantly higher TLOSR rate than the meal. Similarly, distension-induced increase in gastric wall tension, estimated from the measured bag pressure and volume using Laplace's law, was associated with significantly higher TLOSR rates (P < 0.01). In conclusion, the rate of TLOSRs in healthy volunteers is directly related to the degree of proximal gastric distension and pressure-controlled barostat distension is a more potent trigger of TLOSRs than a meal. The latter finding suggests that tension receptor activation is an important stimulus for TLOSRs.     

Intragastric pressure during food intake: a physiological and minimally invasive method to assess gastric accommodation

Background The stomach relaxes upon food intake and thereby provides a reservoir while keeping the intragastric pressure (IGP) low. We set out to determine whether we could use IGP as a measurement for stomach accommodation during food intake. Methods In fasted healthy volunteers (n = 7–17) a manometer and an infusion catheter were positioned in the proximal stomach. After a stabilization period a nutrient drink was intragastrically infused at 15, 30 and 60 mL min^?1. To investigate the effect of impaired accommodation the effect of N^G‐monomethyl‐l ‐arginine (L‐NMMA) was examined. The volunteers scored satiation until maximum, when the experiment ended. The IGP was presented as a change from baseline (mean ± SEM) and compared with repeated measures anova . Key Results Independent on the ingestion speed, the IGP decreased initially and gradually increased thereafter. Volunteers scored maximal satiation after 699 ± 62, 809 ± 90 and 997 ± 120 mL nutrient drink infused (15, 30 and 60 mL min^?1 respectively; P < 0.01). Maximum IGP decrease was 3.4 ± 0.5 mmHg after 205 ± 28 mL, 5.1 ± 0.7 mmHg after 212 ± 46 mL, and 5.2 ± 0.7 mmHg after 296 ± 28 mL infused volume [15, 30 and 60 mL min^?1 respectively; not significant (ns)]. Post hoc analysis showed significant correlations between IGP and satiation score increase. During L‐NMMA infusion IGP was significantly increased while subjects drank significantly less (816 ± 91 vs 1032 ± 71 mL; P < 0.005). Interestingly, the correlation between IGP increase and satiation score increase did not differ after L‐NMMA treatment. Conclusions & Inferences The IGP during nutrient drink ingestion provides a minimally invasive alternative to the barostat for the assessment of gastric accommodation. These findings furthermore indicate that IGP is a major determinant of satiation.     

Influence of sumatriptan on gastric accommodation and on antral contraction in healthy subjects assessed by ultrasonography

Background Oral sumatriptan administration has been reported to delay gastric emptying after liquid meals. The aim of this study was to determine whether delayed gastric emptying is caused by enhanced gastric accommodation, impaired antral contractions, or both using ultrasonography. Methods Ten healthy volunteers were enrolled in this randomized two‐way crossover study. After overnight fasting, the subjects received the liquid meal 60 min after ingesting a 50 mg sumatriptan tablet with 50 mL of water or 50 mL of water alone (control). The cross‐sectional area of the proximal stomach was measured in a supine position after every 100 mL. The frequency and amplitude of the antral contractions were measured in a slightly backward sitting position. The intragastric distribution of the liquid meal was assessed by calculating the proximal stomach/distal stomach ratio (prox/distal ratio). Key Results The cross‐sectional area after drinking 100, 200, and 300 mL of the liquid meal (oral sumatriptan vs control) was 34.49 vs 15.11 cm² (P = 0.0051), 48.00 vs 30.61 cm² (P = 0.0166), and 58.67 vs 47.19 cm² (P = 0.0125), respectively. There was no significant difference in the amplitude of contractions, contraction cycle, motility index, and prox/distal ratio (97.15 vs 97.93%, P = 0.0745; 19.42 vs 19.5 s, P = 0.8590; and 887.58 vs 889.22, P = 0.5751; 9.75 vs 8.41, P = 0.8785; respectively). Conclusions & Inferences Oral sumatriptan administration enhanced gastric accommodation after the ingestion of liquid nutrients, but had no significant effect on antral contractions or intragastric distribution in healthy subjects.     

Therapeutic efficacy of acotiamide in patients with functional dyspepsia based on enhanced postprandial gastric accommodation and emptying: randomized controlled study evaluation by real-time ultrasonography

Background Improvement in subjective symptoms has been reported in functional dyspepsia (FD) patients administered with acotiamide. Improvement was confirmed in meal‐related symptoms, such as postprandial fullness, upper abdominal bloating, and early satiety. We examined the mechanism underlying the effects of acotiamide on gastric accommodation reflex (GAR) and gastroduodenal motility in FD patients. Methods Thirty‐four FD patients (mean age, 40.4 years) were examined ultrasonographically before and after 14–18 days of acotiamide (100 mg t.i.d.) or placebo administration. To assess GAR, expansion rate in cross‐sectional area of the proximal stomach was measured after every 100‐mL ingestion, using a straw, of up to 400 mL of a liquid meal (consommé soup, 13.1 kcal; 400 mL) in a supine position. Next, we measured gastric emptying rate (GER), motility index (MI, antral contractions), and reflux index (RI, duodenogastric reflux) to assess gastroduodenal motility. Patients also completed a survey based on the seven‐point Likert scale both before and after drug administration. Key Results Of the 37 cases, 19 and 18 were administered with acotiamide and placebo A respectively, significant difference was observed in GAR between the acotiamide and placebo groups (21.7%vs 4.4%) after 400 mL ingestion. GER significantly accelerated after treatment in the acotiamide group (P = 0.012), no significant differences were observed in MI and RI between the two groups. Improvement rates were 35.3 and 11.8% for the acotiamide and placebo groups. Conclusions & Inferences Acotiamide significantly enhances GAR and GER in FD patients. Acotiamide may have therapeutic potential for FD patients.     

Characterization of gastric volume responses and liquid emptying in functional dyspepsia and health by MRI or barostat and simultaneous 13C-acetate breath test

Abstract The assessment of gastric accommodation and emptying by different methodologies provides inconsistent results. We aimed to compare magnetic resonance imaging (MRI), barostat and ¹³C‐acetate breath test (BT) for the assessment of gastric volume responses and emptying in healthy controls (HC) and patients with functional dyspepsia (FD). Eight HC and eight FD patients underwent: (i) continuous BT with simultaneous MRI in the upright position after ingestion of isocaloric, 300 kcal, 200 and 800 mL meals, both labelled with 100 mg of ¹³C‐acetate; and (ii) BT with gastric barostat after ingestion of the 200 mL meal. MRI measured total gastric volume and gastric content volume (GCV) at baseline, after filling and during emptying. Meal emptying half‐times (T½) for MRI and BT were calculated (mean ± SD). We found: (i) Initial GCV was lower in FD than in HC (762 ± 22 vs 810 ± 52 mL, P < 0.04) after the 800 mL meal but not the 200 mL meal. T½_MRI was shorter for the 800 mL than the 200 mL meal (P < 0.001), but similar in HC and FD (200 mL: HC 117 ± 30 min vs FD 138 ± 42 min, ns; 800 mL: HC 71 ± 16 min vs FD 78 ± 27 min, ns). In contrast, T½_BT was similar between meals and groups (200 mL: HC 111 ± 11 min vs FD 116 ± 19 min; 800 mL: HC 114 ± 14 min vs FD: 113 ± 17 min). (ii) Barostat measurements showed similar postprandial volume increases between groups. We conclude that direct measurements by MRI provide a sensitive, non‐invasive assessment of gastric accommodation and emptying after a meal. In contrast to MRI, BT did not detect faster emptying of high‐volume compared to low‐volume liquid nutrient meals in HC or FD.