High-viscosity liquid meal accelerates gastric emptying

Adding pectin to an elemental formula increases its viscosity through gelatinization, thus presumably preventing gastro-oesophageal reflux and aspiration pneumonia. We investigated the influence of the viscosity of an elemental formula on gastric emptying. Eleven healthy volunteers underwent three tests at intervals of >1 week. After fasting for >8 h, each subject received a test meal (enteral nutrition solution, enteral solution plus pectin, or water). Then gastric emptying (continuous (13)C breath test), gastro-oesophageal intraluminal pressures, oesophageal pH, and blood levels of glucose, insulin and gastrin were all measured simultaneously. The gastric emptying coefficient was significantly increased by adding pectin to enteral nutrition (3.01 +/- 0.10 vs 2.78 +/- 0.10, mean +/- SE, P < 0.05). The antral motility index was also significantly higher with pectin than without at 45-60 min and 60-75 min after the test meal (526 +/- 237 vs 6.5 +/- 4.6 mmHg s(-1) and 448 +/- 173 vs 2.3 +/- 2.3 mmHg s(-1) respectively; P < 0.05). Plasma glucose was significantly higher with pectin than without it at 60 min after ingestion (141.5 +/- 6.03 vs 125.8 +/- 4.69 microM mL(-1), P < 0.05). In healthy individuals, pectin increased the viscosity of enteral nutrition and accelerated gastric emptying.     

Time-course of recovery of gastric emptying and motility in rats with experimental spinal cord injury

Abstract  We have shown recently that spinal cord injury (SCI) decreases basal gastric contractions 3 days after injury. In the present study we used the [¹³C]-octanoic acid breath test and gastric strain gauges with the aim to investigate the time-course of recovery from postinjury gastric stasis in rats that underwent experimental SCI at the level of the third thoracic (T3) vertebra. Following verification of the [¹³C]-breath test sensitivity in uninjured rats, we conducted our experiments in rats that underwent T3- spinal contusion injury (T3-CI), T3-spinal transection (T3-TX) or laminectomy (control) surgery at 3 days, 1, 3 or 6 weeks postinjury. Our data show that compared to rats that underwent laminectomy, rats that received SCI showed a significant reduction in the cumulative per cent [¹³C] recovery. Although more marked in T3-TX rats, the delayed gastric emptying in T3-CI and T3-TX rats was comparable in the 3 days to 3 weeks period postinjury. At 6 weeks postinjury, the gastric emptying in T3-CI rats recovered to baseline values. Conversely animals in the T3-TX group still show a significantly reduced gastric emptying. Interestingly, the almost complete functional recovery observed in T3-CI rats using the [¹³C]-breath test was not reflected by analysis of spontaneous gastric contractions after SCI. These data indicate that T3-SCI produces a significant reduction in gastric emptying independent of injury severity (T3-CI vs T3-TX) that persists for at least 3 weeks after injury. However, 6 weeks postinjury T3-CI, but not T3-TX, rats begin to demonstrate functional recovery of gastric emptying.     

Influence of continuous isobaric rectal distension on gastric emptying and small bowel transit in young healthy women

Patients with slow transit constipation frequently have delayed gastric emptying. In animals rectal distensions inhibit gastrointestinal motility. In healthy volunteers isovolumetric rectal distensions delay upper gut transit. The purpose of this study was to determine the effect of continuous isobaric rectal distension on gastric emptying and oro-cecal transit in young females. Using validated 13C octanoic and lactose-[13C] ureide breath tests gastric half-emptying time and oro-cecal transit time for a meal were measured in 12 volunteers. The tests were repeated in randomized order: during isobaric balloon distension and during sham distension. Isobaric rectal distension was applied using a polyethylene bag connected to a barostat. Intraballoon pressure was kept just below the threshold for the urge sensation. Mean gastric half-emptying time during rectal distension (92.3 +/-5.1 min) was significantly higher than during sham distension (78.8 +/- 4 min; P = 0.015). Mean oro-cecal transit time during rectal distension (391.3 +/-29.1 min) and sham distension (328.8 +/- 38.4 min) were not significantly different. In conclusion, these findings indicate that isobaric rectal distension inhibits gastric emptying, but not small bowel transit in young healthy women. Studies in patients with constipation are indicated.     

Ghrelin does not stimulate gastrointestinal motility and gastric emptying: an experimental study of conscious dogs

Ghrelin is a peptide that was discovered in endocrine cells of the stomach. However, its action in regulating the fasted and fed motor activity of the digestive tract is not fully understood. In the present study, we examined the effects of an intravenous (i.v.) injection of canine ghrelin on the physiological fasted and fed motor activities in the stomach, duodenum, jejunum and colon of freely moving conscious dogs. An i.v. injection of canine ghrelin released growth hormone in a dose-dependent manner; however, it did not stimulate the motor activity of the digestive tract in either the fasted or the fed state. Moreover, an i.v. injection of high-dose canine ghrelin significantly reduced the motility index in the gastric body in the fasted state. Ghrelin did not accelerate gastric emptying, either. These results differ from previous reports dealing with rodents. It is significant that such results were obtained in research with dogs, which are larger animals.     

Involvement of NO in gastric emptying of semi-solid meal in conscious pigs

The influence of non-selective nitric oxide synthase (NOS) inhibition on gastric emptying of a semi-solid meal was studied in conscious pigs. Antroduodenal motility and fundic compliance were also assessed to evaluate the mechanisms at the origin of potential alteration in gastric emptying pattern. N(G)-nitro-L-arginine methyl ester (L-NAME; 20 mg kg(-1) i.v.) delayed gastric emptying (half-emptying time of 128.98 +/- 16.86 min vs 73.74 +/- 7.73 min after saline, P < 0.05, n = 6) as a result of decreased proximal gastric emptying. No changes were observed for distal gastric emptying as a result of unchanged antral motility. Similarly, no changes were noted on duodenal motor patterns either in the fasted or in the fed state. L-NAME decreased fundic compliance in fasted state (49 +/- 11 mL mmHg(-1) vs 118 +/- 15 mL mmHg(-1) after saline, P < 0.05, n = 6). As this phenomenon is expected to increase emptying rate, the gastroparesis induced by NOS inhibition is thus likely to originate from distal resistive forces. It is concluded that NO positively modulates gastric emptying.     

Relationships between hypoglycaemia and gastric emptying abnormalities in insulin-treated diabetic patients.

We hypothesize that hypoglycaemia in insulin-treated diabetic patients may result from gastric emptying abnormalities causing insulin and food absorption mismatching. We tested gastric emptying in insulin-treated diabetic patients with unexplained hypoglycaemia and without dyspepsia and in diabetic patients without hypoglycaemia, prospectively. Thirty-one diabetic patients with unexplained hypoglycaemic events within 2 h of insulin injection and 18 insulin-treated diabetic patients without hypoglycaemic events underwent gastric emptying breath tests, glycaemic control and autonomic nerve function. Gastric emptying tests were abnormal in 26 (83.9%) and in four (22.2%) patients with and without hypoglycaemia, respectively (P < 0.001). Gastric emptying was significantly slower in hypoglycaemic diabetic patients (t1/2 139.9 +/- 74.1 vs 77.8 +/- 23.3 and t(lag) 95.8 +/- 80.3 vs 32.84 +/- 16.95 min, P < 0.001 for both comparisons; t-tests). A significant association between hypoglycaemic patients and abnormal values of t1/2 and t(lag) was found (P < 0.001). Gastric emptying abnormalities were more frequent in hypoglycaemic patients. We suggest gastric emptying tests for diabetic patients with unexplained hypoglycaemic events.     

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.     

The relationship between gastric pH and the emptying of solid, semisolid and liquid meals

The effect of three different meal constituents, solid, semisolid and liquid, on gastric pH, recorded in the proximal and distal stomach, was evaluated in a prospective study of 20 normal volunteers. The solid and liquid were ingested together as one meal and the semisolid as another. Simultaneous recordings of the rate of gastric emptying of the isotopically labelled meal constituents and the gastric pH were made. The rate of gastric emptying was more rapid for the liquid and semisolid constituents (t_1/2= 35.6, range 9.8–103.3 min and 47.4, range 33.5–120 min, respectively) than for the solid meal constituent (t_1/2= 72.0, range 45.0–103.8 min), P < 0.01. Both the combined meal of solid and liquid and the semisolid meal produced a higher pH response in the proximal stomach than in the distal stomach (5.2, range 2.4–6.1 vs 2.9, range 0.8–5.3 and 5.9, range 4.3–6.6 vs 4.3, range 1.1–5.9), P < 0.01. There were significant correlations between the rate of gastric emptying of all three meal constituents and the decline phase in the gastric pH recorded at both the proximal and distal probes, P < 0.01 (Pearson's correlation). The strongest correlations were found between the rate of gastric emptying and the gastric pH recorded in the proximal stomach. The decline phase of gastric pH followed the emptying of semisolid more closely than the emptying of either solid or liquid.     

Effects of cyclooxygenase-2 inhibitor on glucagon-induced delayed gastric emptying and gastric dysrhythmia in dogs

The objective of this study was to investigate the effects of cyclooxygenase-2 (COX-2) inhibitor (celecoxib) on delayed gastric emptying and gastric dysrhythmia induced by glucagon. The study was performed in six healthy female dogs implanted with four pairs of gastric serosal electrodes, and a duodenal fistula for the assessment of gastric emptying. Each dog was studied in three randomized sessions: control, glucagon and COX-2 inhibitor (celecoxib). Gastric emptying was assessed every 15 min via a duodenal cannula by calculating the amount of collected phenol red which mixed with the test meal and gastric slow waves were recorded at the same time. We found that: (i) glucagon significantly and substantially decreased gastric emptying of liquids (P < 0.001, anova), increased blood glucose (BG) levels, and induced gastric dysrhythmias. The delayed gastric emptying was correlated with the BG level (R = -0.77, P < 0.001) and (ii) celecoxib improved glucagon-induced delayed gastric emptying at 30, 45, 60 and 75 min after feeding. Celecoxib did not blocked dysrhythmic action of glucagon (P > 0.05, anova). In conclusion, glucagon induces delayed gastric emptying partially via COX-2-derived prostaglandins. However, COX-2-derived prostaglandins are not involved in glucagon-evoked gastric dysrhythmia. Selective COX-2 inhibitors may provide a possible therapeutic option for diabetic gastroparesis.     

Role of vagal innervation on intragastric distribution and emptying of liquid and semisolid meals in conscious pigs

The role of vagal innervation on emptying patterns and intragastric distributions of liquid and semisolid meals is still controversial. We aimed to record these features after dorsal, ventral and truncal vagotomies, using external gamma scintigraphy in conscious pigs in which the dorsal vagus specifically innervates the proximal stomach. Imaging of the stomach was performed for all experimental situations and before surgery using 99mTc-labelled glucose and porridge meals. Emptying of liquids was faster after dorsal vagotomy, whereas it was unchanged after ventral and truncal vagotomies (T1/2 = 57 +/- 8.5, 31 +/- 14.4, 54 +/- 9.1 and 42 +/- 14.9 min for intact, dorsal, ventral and truncal vagotomies, respectively). On the other hand, truncal vagotomy significantly reduced the emptying rate of semisolids whereas dorsal and ventral vagotomies had no significant effect (T1/2 = 96 +/- 7.2, 113 +/- 8.1, 75 +/- 9.9 and 260 +/- 56.6 min for intact, dorsal, ventral and truncal vagotomies). Morphological analysis of the gastric shape confirmed an overdistended proximal stomach after truncal vagotomy only. For semisolids, proximal stomach emptying followed the same emptying pattern as the entire stomach, irrespective of the surgical procedure. We concluded that the proximal stomach is the main control for the emptying of liquids and semisolids. The vagal control of overall gastric emptying for semisolids is probably identical to that modulating the intragastric distribution of the meal.     

Gastric emptying in normal subjects: reproducibility and relationship to characteristics of the migrating motor complex

This study was designed to clarify whether a part of the variability in gastric emptying could be ascribed to a relationship between meal ingestion and phase activity of the migrating motor complex and whether reproducibility is increased when meal ingestion takes place in relation to preselected characteristics of the migrating motor complex. We examined 12 healthy males, and the design included three examinations, twice with meal ingestion in a duodenal Phase I, and once in a Phase II. The meal consisted of an omelette labelled with ^99mTc followed by 150 ml water labelled with ¹¹¹In. The results showed that liquid lag phase (min) and was significantly shorter in Phase II than in Phase I (1 vs. 4, P = 0.007). The half emptying time of solid linear phase (min) was reproduced with nearly identical median and range values in the three series (I[1]: 67[51–87]; I[2]: 63[47–80]; 61[47–76]). With meal ingestion in Phase I a significant difference between inter- and intra-individual variance could not be demonstrated. With meal ingestion in Phase I a second examination in Phase I did not increase reproducibility of any of the variables compared to a second examination in Phase II. In conclusion, scientific investigations on gastric emptying have to be performed with phase related meal ingestion and a double-radionuclide technique.     

Cyclooxygenase-2 inhibition increases gastric tone and delays gastric emptying in rats.

We evaluated the effects of cyclooxygenase-2 (COX-2) selective inhibitors, COX-1 selective inhibitor, or COX non-selective inhibitor on gastric emptying and intestinal transit of liquids, and evaluated the effect of a COX-2 selective inhibitor on gastric tonus (GT). Male Wistar rats were treated per os with saline (control), rofecoxib, celecoxib, ketorolac, rofecoxib + ketorolac, celecoxib + ketorolac, or indomethacin. After 1 h, rats were gavage-fed (1.5 mL) with the test meal (5% glucose solution with 0.05 g mL(-1) phenol red) and killed 10, 20 or 30 min later. Gastric, proximal, medial or distal small intestine dye recovery (GDR and IDR, respectively) were measured by spectrophotometry. The animals of the other group were treated with i.v. valdecoxib or saline, and GT was continuously observed for 120 min using a pletismomether system. Compared with the control group, treatment with COX-2 inhibitors, alone or with ketocolac, as well as with indomethacin increased GDR (P < 0.05) at 10-, 20- or 30-min postprandial intervals. Ketorolac alone did not change the GDR, but increased the proximal IDR (P < 0.05) at 10 min, and decreased medial IDR (P < 0.05) at 10 and 20 min. Valdecoxib increased (P < 0.01) GT 60, 80 and 100 min after administration. In conclusion, COX-2 inhibition delayed the gastric emptying of liquids and increased GT in rats.     

Effects of postgastric 13C-acetate processing on measurement of gastric emptying: a systematic investigation in health

Abstract Uniform postgastric processing of the gastric emptying (GE) marker ¹³C‐acetate (Ac) is an unverified assumption behind its widespread application to measure GE. This study assessed the postgastric processing of Ac administered by intraduodenal (i.d.) infusion simulating different physiological conditions. ¹³CO₂ in breath was assessed in three groups of six volunteers after i.d. administration of A: Different caloric densities (0.75/1.5/3 kcal min^?1) in a 200 mL meal at constant 1 mg Ac min^?1 simulating a physiological range of nutrient delivery rates; B: different tracer delivery rates (0.5/1.0/2.5 mg Ac min^?1) simulating delayed, normal and increased GE; C1: a 500 mL meal resulting in same marker and caloric delivery compared to protocol A; C2: 50 mL water bolus injections of 12.5/25/50/100 mg Ac and C3 bolus injections of 50 mg Ac in 50/100/200 mL water in randomized order. A: ¹³CO₂ excretion was independent of caloric load (P = 0.59). B: The dynamic of ¹³CO₂ excretion was modulated by tracer elimination which was in turn dependent on the speed of tracer delivery, i.e. with faster deliveries resulting in lower ¹³CO₂ recovery during infusion (P < 0.001). C: Increasing Ac doses resulted in decreased ¹³CO₂ recovery (P < 0.001) over the first hour. ¹³CO₂ recovery kinetics was independent of the volume delivered. This study shows ¹³C‐acetate absorption and metabolism is independent of the volume and caloric delivery of test meals. The ‘lag’ in estimates of GE derived from ¹³CO₂ breath tests is due to a postgastric, dose‐dependent delay to ¹³CO₂ elimination. This can be corrected for in analytical derivations of GE parameters based on ¹³C‐acetate breath test measurements.     

Gastric secretion does not affect the reliability of the 13C‐acetate breath test: A validation of the 13C‐acetate breath test by magnetic resonance imaging

Background ¹³C‐Acetate labeled meals are widely used to determine meal emptying by means of analyzing resulting ¹³CO₂ exhalation dynamics. In contrast to the underlying metabolic processes, only few ¹³C breath test meal emptying studies have focused on intragastric processes that may alter ¹³CO₂ exhalation. This work assessed the effect of enhanced gastric secretion on the reliability of half emptying time (t50) measurements by ¹³C‐acetate breath test. Methods ¹³CO₂ exhalation data were acquired in a double‐blind, randomized, cross‐over gastric emptying study in 12 healthy volunteers receiving either pentagastrin or placebo intravenously. The standard method proposed by Ghoos et al. was applied to calculate t50 (t50_Ghoos) from ¹³CO₂ exhalation data, which were compared and tested for agreement to meal half emptying times (t50_MV) from concurrent recorded MRI (magnetic resonance imaging) volume data. In addition, the accumulated gastric secretion volumes during infusion as detected by MRI (AUC_SV₆₀) were correlated with the corresponding cumulative percent ¹³C doses recovered (cPDR₆₀). Key Results t50_Ghoos and t50_MV showed a linear correlation with a slope of 1.1 ± 0.3 (r² = 0.67), however, a positive offset of 136 min for t50_Ghoos. No correlation was detected between AUC_SV₆₀ and cPDR₆₀ (r² = 0.11). Both, breath test and MRI, revealed a prolonged t50 under pentagastrin infusion with median differences in t50_Ghoos of 45[28–84] min (P = 0.002) and t50_MV of 39[28–52] min (P = 0.002). Conclusions & Inferences This study suggests that ¹³CO₂ exhalation after ingestion of a ¹³C‐labeled liquid test meal is not affected by stimulated gastric secretion, but is rather reflecting the dynamics of meal or caloric emptying from the stomach.     

Delayed gastric emptying rates and impaired antral motility in children fulfilling Rome III criteria for functional abdominal pain

Background Gastric sensorymotor dysfunctions have been implicated in the pathophysiology of some functional gastrointestinal disorders, such as functional dyspepsia and irritable bowel syndrome. Therefore, we hypothesized that abnormal gastric emptying and impaired antral motility are possible underlying mechanisms of symptoms in children with functional abdominal pain (FAP). Methods Hundred and two children [37 (36.3%) males, 4–14 years, mean 7.8 years, SD 2.7 years] fulfilling Rome III criteria for FAP were recruited for this study. An age and sex compatible group of healthy children (n = 20) were selected as controls [8 (40%) males, 4–14 years, mean 8.4 years, SD 3.0 years]. Liquid gastric emptying rate (GER) and antral motility parameters (amplitude of antral contractions, frequency of antral contractions and antral motility index) were assessed using a previously reported ultrasound method. Key Results Average GER (42.1% vs 66.2% in controls), amplitude of antral contractions (56.5% vs 89%), frequency of contractions per 3 min (8.5 vs 9.3), and antral motility index (4.9 vs 8.3) were significantly lower in patients with FAP compared with controls (P < 0.01). Fasting antral area was higher in patients (1.4 vs 0.6, P < 0.0001). GER negatively correlated with the scores obtained for severity of abdominal pain (r = ?0.29, P = 0.004). Conclusions & Inferences Gastric emptying rate and antral motility parameters were significantly impaired in patients with FAP and GER negatively correlated with symptom severity. These findings highlight the possible role of gastrointestinal motility abnormalities in the pathophysiology of childhood FAP.