Gastric Emptying Curves Research Articles

Measurement of Gastric Emptying Using a 13C-octanoic Acid Breath Test with Wagner-Nelson Analysis and Scintigraphy in Type 2 Diabetes.

Breath tests utilising 13C-labelled substrates for the assessment of gastric emptying have been applied widely. Wagner-Nelson analysis is a pharmacokinetic model that can be utilised to generate a gastric emptying curve from the % 13CO2 measured in breath samples. We compared Wagner-Nelson analysis with (i) scintigraphy and (ii) conventional breath test modelling to quantify gastric emptying in type 2 diabetes. Thirteen patients (age 68.1±1.5 years, body mass index 31.0±0.9 kg/m2, HbA1c 6.3±0.2%) consumed a mashed potato meal comprising 65 g powdered potato, 20 g glucose, 250 ml water, an egg yolk labelled with 100 μL 13C-octanoic acid and 20MBq 99mTc-calcium phytate. Scintigraphic data were acquired and breath samples collected for 4 hours after the meal. Gastric emptying curves were derived based on each technique; the 50% emptying time and intragastric retention at 60 min were also calculated. With Wagner-Nelson analysis, a Kel=0.60 (the elimination constant) best approximated the scintigraphic gastric emptying curve. There was a relationship between the T50 calculated with scintigraphy and by both Wagner-Nelson Kel=0.60 (r2=0.45, P<0.05) and conventional analysis (r2=0.44, P<0.05). There was no significant difference in the 50% gastric emptying time for scintigraphy (68.5±4.8 min) and Wagner-Nelson Kel=0.60 (71.3±4.5 min), however, the 50% gastric emptying time calculated by conventional analysis was much greater at 164.7±6.0 min (P<0.001). In type 2 diabetes, gastric emptying of a mashed potato meal measured using a 13C-octanoic acid breath test analysed with Wagner-Nelson Kel=0.60 closely reflects measurements obtained with scintigraphy, whereas, in absolute terms, the conventional breath test analysis does not.

Achieving realistic gastric emptying curve in an advanced dynamic in vitro human digestion system: experiences with cheese-a difficult to empty material.

Nowadays, in vitro digestion models have received growing interest in recent years to track the digestive fate of foods in the gastrointestinal tract. A major challenge in the development of more physiologically relevant in vitro gastric models is to simulate realistic gastric emptying. In this study, an advanced dynamic in vitro human gastric system was investigated for its potential in achieving the above. The mechanisms for controlling the gastric emptying rate by modulations of the peristaltic moving distance, the pylorus opening size/frequency, and the stomach tilting angle in relation to time are illustrated. With solid cheese, a difficult food material for emptying, different combinations of the operational parameters of the stomach system were evaluated. The system was steered to attain consistent gastric emptying curve with the theoretical data by optimizing operational parameters. By fitting the gastric retention data with a power-exponential model, which is a common approach for describing gastric emptying, the total meal achieved an average emptying half-time (t1/2) of 84.5 min and a curve shape coefficient (β) of 1.69, similar to the theoretical data reported in the literature, where the values of t1/2 and β were 85 min and 1.8, respectively (p > 0.05). Furthermore, the mean median particle size was significantly decreased from the initial 2.80 mm (cheese cubes) to the final 1.35 mm (p < 0.05). There are few particles greater than 2 mm observed in the emptied cheese digesta throughout the digestion process. These suggest the powerful gastric grinding and sieving capacity exhibited by the in vitro system. The current study demonstrates that a well-considered in vitro system can offer a reasonable approach for tracking the structural and physicochemical changes of foods during digestion in the stomach, which is practically meaningful.

High temporal resolution gastric emptying breath tests in mice.

Gastric emptying is a complex physiological process regulating the division of a meal into smaller partitions for the small intestine. Disrupted gastric emptying contributes to digestive disease, yet current measures may not reflect different mechanisms by which the process can be altered. We have developed high temporal resolution solid and liquid gastric emptying breath tests in mice using [13 C]-octanoic acid and off axis- integrated cavity output spectroscopy (OA-ICOS). Stretched gamma variate and 2-component stretched gamma variate models fit measured breath excretion data. These assays detect acceleration and delay using pharmacological (7.5mg/kg atropine) or physiological (nutrients, cold exposure stress, diabetes) manipulations and remain stable over time. High temporal resolution resolved complex excretion curves with 2 components, which was more prevalent in mice with delayed gastric emptying following streptozotocin-induced diabetes. There were differences in the gastric emptying of Balb/c vs C57Bl6 mice, with slower gastric emptying and a greater occurrence of two-phase gastric emptying curves in the latter strain. Gastric emptying of C57Bl6 could be accelerated by halving the meal size, but with no effect on the occurrence of two-phase gastric emptying curves. A greater proportion of two-phase gastric emptying was induced in Balb/c mice with the administration of PYY (8-80nmol) 60min following meal ingestion. Collectively, these results demonstrate the utility of high temporal resolution gastric emptying assays. Two-phase gastric emptying is more prevalent than previously reported, likely involves intestinal feedback, but contributes little to the overall rate of gastric emptying.

Effects of electroacupuncture at acupoints with different nerve segments on gastric emptying in OT gene knockout mice

To observe the effects of electroacupuncture (EA) at acupoints with different nerve segments on gastric emptying in oxytocin (OT) gene knockout mice, and to explore the role of paraventricular nucleus OT in EA regulating gastric function. Twenty OT knockout mice and twenty wild-type mice (8-9 weeks old, male and female in half) were divided into a control group, a Zusanli (ST 36) group, a Neiguan (PC 6) group and a Weishu (BL 21) group randomly, 5 mice in each group. The mice in the control group received no acupuncture; the mice in the Zusanli (ST 36) group, Neiguan (PC 6) group and Weishu (BL 21) group were treated with EA at unilateral "Zusanli" (ST 36), "Neiguan" (PC 6) and "Weishu" (BL 21) for 15 min respectively. Subsequently, the mice were treated with intragastric administration with milk loaded with technetium-99m diethylene triamine pentaacetic acid (99mTc-DTPA), immediately followed by scanning of single photon emission computed tomography (SPECT) to test gastric emptying for 50 min; the original data was collected and analyzed to obtain the half gastric emptying time (GET 1/2), 50-min stomach residue rate and gastric emptying curve. The wild-type mice group:compare with the control group, after EA at "Zusanli" (ST 36) and "Neiguan" (PC 6), the GET 1/2 and 50-min stomach residue rate were significantly reduced, which could improve the gastric emptying of wild-type mice (P<0.01, P<0.05); after EA at "Weishu" (BL 21), the GET 1/2 and 50-min stomach residue rate were significantly increased, which could inhibit the gastric emptying of wild-type mice (P<0.01, P<0.05). The OT gene knockout mice group:compared with the control group, EA at "Zusanli" (ST 36) and "Neiguan" (PC 6) had no significant effects on gastric emptying (both P>0.05); after EA at "Weishu" (BL 21), the GET 1/2 and 50-min stomach residue rate were significantly increased, which could inhibit the gastric emptying of OT gene knockout mice (both P<0.01). Gastric emptying curve:the gastric emptying of OT gene knockout mice was significantly faster than that of wild-type mice. The effects of EA at acupoints with different nerve segments on gastric emptying in mice are different, and the knockout of OT gene could accelerate the gastric emptying, and influence the acupuncture effect of several acupoints. It is suggested the paraventricular nucleus OT neurons, as the initiating device of autonomic nervous pathways, might participate in EA regulating the gastric function to inhibit the gastric emptying, with the form of neural and neuroendocrine.

What is the manner of gastric emptying after ingestion of liquids with differences in the volume under uniform glucose-based energy content?

We previously demonstrated that the gastric emptying rate of liquids chiefly depended on the total amount of calories (energy content) in a uniform volume. The aim of the present study was to examine the effects of different volumes of liquids with a uniform energy content on gastric emptying. Three types of test solutions were prepared with a uniform amount of calories (200kcal provided by glucose) and step-wise increments in volume (200ml, 400ml, and 600ml). The gastric volume of each solution was determined by ultrasound measurements of the gastric antral cross-sectional area after their ingestion by 8 healthy volunteers. The mean gastric volume decreased exponentially to nearly 0ml 70min after ingestion in the 200ml group, 90min in the 400ml group, and 100min in the 600ml group. Each gastric emptying curve converged with identical slopes on the graph when the points at which the gastric emptying curves of the 200ml and 400ml groups reached the zero point on the Y-axis (mean gastric volume) were shifted toward 110min on the X-axis (time scale). The volume of liquid ingested with a uniform glucose-based energy content is a critical determinant of liquid gastric emptying. The gastric emptying time may be predicted following the ingestion of an isocaloric liquid with any volume over a predefined range once a gastric emptying curve following the ingestion of a liquid has been plotted on a graph. UMIN000014930.

Simulation research on gastric emptying measurement experiment by electrical impedance tomography with three-layer electrodes

Objective To verify the effectiveness of electrical impedance tomography (EIT) with multi-layer electrodes in gastric emptying measurement by simulation experiments using EIT with three-layer electrodes. Methods Firstly, EIT system with three-layer electrodes and gastric emptying measurement simulation equipment was designed and constructed to simulate gastric emptying process and obtain EIT reconstruction images. Secondly, the region where the electrical characteristic of gastric changes was selected as region of interest. Finally, the relative impedance change rate in region of interest for every image obtained from all three layers was consecutively recorded, then the gastric emptying curve was formed and gastric emptying time was calculated. Results There are obvious differences among the sharp of impedance change curves of interested region for three layers, and the gastric emptying time and process of each layer is also different from one another. It is suggested that the passing path and emptying manner of food in gastric emptying process reflected by EIT images varied from layer to layer. Therefore, the necessity and feasibility of using EIT with three-layer electrodes in gastric emptying measurement study is verified. Conclusions EIT with three-layer electrodes can provide more abundant information of gastric motility function associated with gastric emptying pathology and physiology state. It is likely to be a noninvasive, convenient and effective imaging method for the detection and evaluation research on gastric emptying and gastric motility. Key words: Electrical impedance tomography; Three-layer imaging; Gastric emptying; Simulation experiments

Temporary Endoscopic Stimulation in Gastroparesis-like Syndrome.

Background/AimsGastroparesis-like syndrome (GLS) is defined as gastroparesis-like symptoms with normal gastric scintigraphy. While the efficacy of gastric electrical stimulation (GES) in gastroparesis is well known, the utility of GES in GLS is largely unknown. Our aim was to clarify the role of GES in GLS. We implanted consecutive patients with symptoms of gastroparesis with temporary gastric electrical stimulation and observed changes in gastric scintigraphy and total symptom score.MethodsFive hundred and fifty-one patients suffering from symptoms of gastroparesis (nausea, vomiting, bloating/distension, anorexia/early satiety, and abdominal pain) with negative endoscopy underwent gastric scintigraphy with analysis of 1) solid radio-nuclide gastric emptying at 1, 2, and 4 hours (% remaining); 2) area under the gastric emptying curve (AUC) at 1, 2, and 4 hours; and 3) total gastric emptying test (GET) (the sum of 1, 2, and 4 hour values). Patients were stratified into: delayed gastric emptying, normal gastric emptying, and rapid gastric emptying (Appendix). Of the 551 patients in the larger cohort, 379 had implantation of temporary gastric electrical stimulation (tGES). Gastrointestinal symptoms and gastric emptying were com -pared pre and post tGES implantation.ResultsAfter tGES, 2 hour gastric retention decreased (P < 0.01) for the delayed patients, and increased (P < 0.001) for normal and rapid patients. These changes were accompanied by improvements (P < 0.001) in vomiting, nausea, and total symptom scores in all 3 subgroups.ConclusionsGastric electrical stimulation may be an effective therapy for treating the symptoms of gastroparesis with normal gastric emptying. Further exploration of endoscopic electrical stimulation as a treatment for gastroparesis-like symptoms with non-delayed gastric emptying is needed.

A gamma variate model that includes stretched exponential is a better fit for gastric emptying data from mice.

Noninvasive breath tests for gastric emptying are important techniques for understanding the changes in gastric motility that occur in disease or in response to drugs. Mice are often used as an animal model; however, the gamma variate model currently used for data analysis does not always fit the data appropriately. The aim of this study was to determine appropriate mathematical models to better fit mouse gastric emptying data including when two peaks are present in the gastric emptying curve. We fitted 175 gastric emptying data sets with two standard models (gamma variate and power exponential), with a gamma variate model that includes stretched exponential and with a proposed two-component model. The appropriateness of the fit was assessed by the Akaike Information Criterion. We found that extension of the gamma variate model to include a stretched exponential improves the fit, which allows for a better estimation of T1/2 and Tlag. When two distinct peaks in gastric emptying are present, a two-component model is required for the most appropriate fit. We conclude that use of a stretched exponential gamma variate model and when appropriate a two-component model will result in a better estimate of physiologically relevant parameters when analyzing mouse gastric emptying data.

Involvement of endogenous glucagon-like peptide-1 in regulation of gastric motility and pancreatic endocrine secretion

Objective. To study the role of endogenous glucagon-like peptide-1 (GLP-1) on gastric emptying rates of a solid meal as well as postprandial hormone secretion and glucose disposal. Material and methods. In nine healthy subjects, gastric emptying of a 310-kcal radio-labelled solid meal and plasma concentrations of insulin, glucagon and glucose were measured during infusion of saline or the GLP-1 receptor antagonist exendin(9-39)amide (Ex(9-39)) at 300 pmol·kg−1·min−1. Results. Ex(9-39) infusion had no effect on the total gastric emptying curve, but changed the intra-gastric distribution of the meal. During infusion of Ex(9-39), more content stayed in the upper stomach (79.1 ± 2.5% of total during Ex(9-39) compared to 66.6 ± 5.7% during saline at 5 min). During Ex(9-39) infusion, higher concentrations of plasma glucagon were measured both before (after 40 min of Ex(9-39) infusion the glucagon level was 15.1 ± 0.7 pmol·L−1 compared to 5.4 ± 1.4 during saline) and after the meal, and postprandial GLP-1 levels increased. Basal insulin and glucose levels were not affected by Ex(9-39), but the postprandial rise of insulin and glucose enhanced during Ex(9-39). Conclusions. Endogenous GLP-1 is involved in the regulation of gastric motility in relation to meal intake and also in the regulation of postprandial insulin and glucose levels. Furthermore, endogenous GLP-1 seems to tonically restrain glucagon secretion.

Investigation of Gastric Emptying Disorders in Patients with Functional Dyspepsia Reveals Impaired Inhibitory Gastric Emptying Regulation in the Early Postcibal Period

Background/Aims: The aim of the study was to investigate gastric emptying profiles in patients with postprandial distress syndrome (PDS) as a means to understand relationships between gastric emptying and dyspepsia. Methods: Gastric emptying times were measured using a ¹³C breath test. In addition to comparisons of ¹³C half excretion times (t 1/2 ex) between patients with PDS and healthy subjects, gastric emptying (%dose/h) curves were analyzed using a multipeak curve-fitting technique, and fitted curves were differentiated to measure the slope of curves for each time point. Results: (1) During the early postcibal period, the slope of %dose/h curves in 27% of patients with PDS was larger than the average slope derived from healthy subjects. The t 1/2 ex was also higher in these patients relative to healthy subjects. (2) During the midpostcibal period, the slope of %dose/h curves in 36% of PDS patients was larger than the average slope derived from healthy subjects. There was a trend toward lower t 1/2 ex values for these patients relative to control subjects. (3) When t 1/2 ex was calculated overall, however, there was no significant difference between healthy subjects and patients with PDS. Conclusion: Our findings document abnormal gastric outflow in patients with PDS. In some patients, there appears to be a significant correspondence between PDS-related dyspepsia and accelerated gastric emptying in the early postcibal period, whereas other patients showed a similar correspondence between dyspepsia and impaired inhibitory gastric emptying regulation in the midpostcibal period.

Orlistat accelerates gastric emptying and attenuates GIP release in healthy subjects

Orlistat, an inhibitor of digestive lipases, is widely used for the treatment of obesity. Previous reports on the effect of orally ingested orlistat together with a meal on gastric emptying and secretion of gut peptides that modulate postprandial responses are controversial. We investigated the effect of ingested orlistat on gastric emptying and plasma responses of gut peptides in response to a solid mixed meal with a moderate energy load. In healthy subjects, gastric emptying was determined using scintigraphy and studies were performed without and with 120 mg of orlistat in pellet form in random order. Orlistat shortened t lag and t half and decreased the area under the gastric emptying curve. Orlistat significantly attenuated the secretion of glucose-dependent insulinotropic polypeptide (GIP) but did not alter the plasma responses of cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), pancreatic polypeptide (PP), and insulin. There was no peptide YY (PYY) response. Area under the curve of gastric emptying was positively correlated with integrated secretion of GIP (r=0.786) in orlistat and was negatively correlated with integrated plasma response of GLP-1 (r=-0.75) in control experiments, implying that inhibition of fat absorption modifies determinants of gastric emptying of a meal. Orlistat administered similar to its use in obesity treatment accelerates gastric emptying of a solid mixed meal with a moderate energy load and profoundly attenuates release of GIP without appreciably altering plasma responses of CCK, GLP-1, and PP. Since GIP is being implemented in the development of obesity, its role in weight control attained by orlistat awaits further investigation.

Gastric Emptying is not Affected by Sleeve Gastrectomy—Scintigraphic Evaluation of Gastric Emptying after Sleeve Gastrectomy without Removal of the Gastric Antrum

The aim of this study is to clarify whether laparoscopic sleeve gastrectomy (LSG) to treat morbid obesity causes changes in gastric emptying. Gastric emptying scintigraphy was performed before and 3 months after LSG, in 21 consecutive morbidly obese patients. After an overnight fast, subjects consumed a standard semi-solid meal, to which 0.5 mCi Tc99-labeled sulfur colloid had been added. The meal was consumed within 10 min. Scintigraphic imaging was performed with a gamma camera immediately after the completion of the meal as well as after 30, 60, 120, 180, and 240 min. Quantitative and qualitative analysis was performed by drawing a region of interest (ROI) enclosing the stomach on the anterior and the posterior images. Time 0 was considered the time of meal completion (all the ingested activity) and was defined as 100% retention. The same ROI was used on all consecutive images of the same projection for the same patient. The geometric mean of the anterior and the posterior counts for each time point is calculated and corrected for Tc(99m) decay. Gastric emptying curves were constructed. T 1/2 is the time interval between completion of the meal and the point at which half of the meal (by radioactivity counts) has left the stomach. Retention is expressed as the percent remaining in the stomach at each time point (half, 1, 2, 3, 4 h). The mean T 1/2 raw data was 62.39+/-19.83 and 56.79+/-18.72 min (p=0.36, t=-0.92, NS) before and 3 months after LSG, respectively. The T 1/2 linear was 103.64+/-9.82 and 106.92+/-14.55, (p=0.43, t=-0.43, NS), and the linear fit slope 0.48+/-0.04 and 0.47+/-0.05 (p=0.48, t=0.7, NS). LSG with antrum preservation as performed in this series has no effect on gastric emptying.

Rabeprazole delays gastric emptying of a nutrient liquid

It is generally considered that gastric acid suppression delays gastric emptying of solid meals because gastric hypoacidity impairs peptic digestion and antral triturition. Rabeprazole is one of the most potent acid suppressants. We conducted this cross-over study to investigate if rabeprazole delays gastric emptying of liquid nutrients, for which peptic digestion is unnecessary. On two randomized occasions, 13 healthy male volunteers underwent the (13)C-acetate breath test following ingestion of a 300 kcal-liquid meal. On one occasion, they had received 20 mg rabeprazole for the preceding 2 days and 1 h before the test. On another, they took no pretreatment. Based on 4 h breath samples, the half (13)CO(2) excretion time (t(1/2b)) and the time of maximal excretion (t(max)) were calculated as overall measures of gastric emptying. In addition, time profiles of gastric emptying were generated using the Wagner-Nelson analytical method, which creates the gastric emptying curve as accurately as the scintigraphy. Rabeprazole significantly prolonged t(max) but unchanged t(1/2b). The gastric emptying profiles showed that rabeprazole evoked a segmental slowing of gastric emptying during 0.5-1.25 h of post-meal ingestion. Rabeprazole suppresses gastric emptying of a liquid nutrient 0.5 h after meal ingestion. We have speculated that: (i) rabeprazole delays gastric emptying via a mechanism other than acid-pepsin maldigestion; and (ii) rabeprazole may intensify the post-gastric feedback regulation system (>0.5 h of post-meal).

Free Fatty Acids Have More Potent Effects on Gastric Emptying, Gut Hormones, and Appetite Than Triacylglycerides

The effects of fat on gastric emptying (GE), gut hormones, and energy intake are dependent on digestion to free fatty acids (FFAs). In animals, small intestinal oleic acid inhibits energy intake more potently than the triacylglyceride (TG) triolein, but there is limited information about the comparative effects of FFA and TG in human beings. We compared the effects of FFA and TG on GE, gut hormone secretion, appetite, and energy intake in healthy males. Nine men (age, 23 +/- 2 y; body mass index, 22 +/- 1 kg/m(2)) were studied on 3 occasions to evaluate the effects of (1) 40 g oleic acid (FFA, 1830 kJ), (2) 40 g macadamia oil (TG, 1856 kJ; both 600-mL oil-in-water emulsions stabilized with 4% milk protein and labeled with 15 MBq (123)I), or (3) 600 mL 4% milk protein (control, 352 kJ), administered intragastrically, on GE, plasma cholecystokinin (CCK) and peptide-YY (PYY) levels, appetite perceptions, and subsequent energy intake. GE of FFA was much slower than that of TG (P < .05), with greater retention of FFA, than TG, in the proximal stomach (P < .001). Hunger was less (P < .05), and fullness was greater (P < .05), after FFA when compared with control and TG. Increases in plasma CCK and PYY levels were greater after FFA than TG or control (P < .05). Energy intake tended to be less after FFA compared with TG (control, 4754 +/- 610 kJ; TG, 5463 +/- 662 kJ; FFA, 4199 +/- 410 kJ). FFAs empty from the stomach more slowly, but stimulate CCK and PYY and suppress appetite more potently than TG in healthy human beings.

Assessment of the Preserved Function of the Remnant Stomach in Pylorus‐preserving Gastrectomy by Gastric Emptying Scintigraphy

This study evaluated the preserved function of the remnant stomach by gastric emptying scintigraphy in patients who underwent pylorus-preserving gastrectomy (PPG), and it investigated whether this examination method is a useful tool for evaluation. The residual stomach function was evaluated by gastric emptying scintigraphy in 45 patients with early gastric cancer who had undergone PPG. Function was classified as rapid, intermediate, and delayed emptying types according to gastric emptying curves. Then, the relationships were examined between the gastric emptying types and postprandial symptoms, food intake status, body weight changes, and endoscopic findings. Seventy-three percent of the PPG patients were classified as belonging to the intermediate emptying type, and the remainder to the delayed emptying type. The frequencies of complaints such as epigastric fullness, nausea, and vomiting were high in the delayed emptying-type patients. The intermediate emptying-type patients consumed larger amounts of food and gained more weight than the delayed emptying-type patients. It was difficult to estimate gastric emptying function from endoscopic findings. Gastric function was evaluated by gastric emptying scintigraphy in PPG patients. This method might be useful not only for evaluating the motor function of the remnant stomach, but also for predicting postoperative status.

Measurements of gastric emptying during continuous nasogastric infusion of liquid feed: Electric impedance tomography versus gamma scintigraphy

Continuous nasogastric infusion is commonly used to deliver enteral feed but current methods used to assess tolerance based on aspiration and measurement of gastric residual volume have been criticised. Electric impedance tomography (EIT) measures gastric emptying by monitoring changes in epigastric impedance when a meal progressively empties from the stomach. (1) to establish whether EIT was a valid method for measuring gastric emptying during continuous nasogastric infusion by comparing it with gamma scintigraphy (GS) and (2) to provide data on gastric emptying patterns during continuous nasogastric infusion. Gastric emptying of 400 ml of enteral feed given over 200 min was measured simultaneously using EIT and GS in 10 healthy volunteers (five male and five female). Gastric emptying curves were obtained in 10 subjects by EIT but only eight by GS. Visual examination of the curves showed reasonable agreement. Patterns of emptying and filling during continuous nasogastric infusion were variable between individuals; the prevailing pattern was a trend towards a steady-state volume of approximately 50-125 ml. While EIT does not provide an accurate estimate of gastric volume during continuous infusion, it does show patterns of gastric emptying over time. With further development this could make it a useful tool for monitoring gastric emptying in patients at risk of gastroparesis.

Magnetic resonance imaging of the behaviour of oil-in-water emulsions in the gastric lumen of man

Pre-processed foods often contain a high percentage of lipid, present as emulsions stabilised with various surface-active agents. The acidic gastric environment can affect the behaviour of such emulsions, modifying the lipid spatial distribution and, in turn, the rate of gastric emptying and nutrient delivery to the gut. The aim of the present study was to use echo-planar magnetic resonance imaging (EPI) to determine the behaviour of model olive oil emulsions during gastric processing. Six healthy male volunteers were intubated nasogastrically on two separate occasions and fed 500 ml 15 % (w/w) olive oil-in-water, surfactant-stabilised emulsions designed to have identical droplet size distribution and which were either stable or unstable under gastric acid conditions. EPI was used to assess the oil fraction of the intragastric emulsions, gastric emptying and to visualise the spatial distribution of the oil at 10, 30 and 50 min postprandially. The in vivo imaging measurements of the oil volume fraction of the emulsions correlated well (r 0.66, acid-stable; r 0.52, acid-unstable) with that assayed in the gastric aspirates. Compared with the acid-stable emulsion, the acid-unstable emulsion in the gastric lumen rapidly separated into lipid-depleted 'aqueous' and lipid layers. Phase separation in the acid-unstable meal allowed the oil-depleted component to empty first and more rapidly than the stable emulsion as determined by the gastric emptying curves. These pilot data suggest that gastric processing and emptying of high-fat foods could be manipulated by careful choice of emulsifier.

Measurement of gastric emptying by the 13C-octanoate breath test—rationalization with scintigraphy

The 13C-octanoate breath test has not achieved universal acceptance for the measurement of solid phase gastric emptying, largely because the results are not comparable with those from direct methods such as scintigraphy. To convert breath-test data to their scintigraphic equivalent scale corrections are applied which have been obtained from population studies, but there is no guarantee that these are applicable in all cases. We propose an alternative method applicable on an individual basis based upon a simple physiological model which does not require any change to the breath-test protocol. It is demonstrated by comparison with scintigraphy and the octanoate saliva test. Results from an existing dataset of simultaneous breath test, saliva test and scintigraphic determinations of solid phase gastric emptying from nine healthy subjects were re-analysed. The corrected breath tests gave gastric emptying curves which were shown to be not significantly different to those obtained from scintigraphy. The method provides a simple but effective way of generating gastric emptying curves from breath-test data that are directly comparable with direct measurement methods, which is advantageous since it allows the whole of the gastric emptying profile to be generated, not just values for the lag phase and half-emptying times.

Gastric emptying function changes in patients with thyroid cancer after withdrawal of thyroid hormone therapy.

Hypothyroidism is commonly thought to cause decreased gastric emptying but is mostly associated with autoimmune disease. In the present study the gastric emptying function of thyroid cancer patients with severe hypothyroidism of short duration was evaluated with a radionuclide solid meal gastric emptying study. Twenty-two patients who had undergone surgical operation and (131)I ablation for thyroid cancer participated in solid meal gastric emptying studies before the withdrawal of thyroxine and then again 4 weeks after the withdrawal of thyroxine. Eleven patients had an additional gastric emptying study at 6 weeks after withdrawal of thyroxine. Gastric emptying curves and emptying parameters were calculated. Student's paired t-test was used for statistical analysis of data for all cases between the baseline and at 4 weeks after withdrawal. An additional repeated measure anova with multiple comparisons was performed on data between baseline, 4 weeks and 6 weeks after withdrawal for the other 11 patients. All P values presented are two-tailed and the significance level is 0.05. Hypothyroidism status was confirmed by the marked change of the serum thyroxine and thyroid-stimulating hormone 4 weeks and 6 weeks after withdrawal of the thyroxine replacement (P < 0.001). The gastric half-emptying time and emptying rate changed significantly after short-term severe thyroid hormone deficiency (P < 0.005). However, the length of the lag phase did not have a statistically significant change at 4 weeks or 6 weeks after withdrawal of the thyroxin replacement (P = 0.219 and 0.142). Hypothyroidism following the withdrawal of the thyroxine replacement in thyroid cancer patients preparing for (131)I cancer work-up can significantly prolong gastric half-emptying time and emptying rate.

Gastric clearance of radiopaque markers in the evaluation of gastric emptying rate

Background: The study of gastric emptying rate of solids using radiopaque indigestible solid markers has been a poorly employed technique because some kinds of markers do not leave the stomach at the same time as the meal but during the interdigestive migrating motor complex (IMMC). The aim of this study was to evaluate whether markers of particular shape and size can be successfully employed for this purpose. Methods: Twenty-eight non-ulcer dyspeptic (NUD) patients and 20 healthy volunteers received a standard solid meal (790 Kcal) together with 20 small polyethylene radiopaque cylinders (5 mm × 2 mm in diameter). Gastric emptying rate was evaluated by ultrasound while the emptying of markers was simultaneously followed by X-rays using a brilliance intensifier. Results: Final emptying time (FET = time when the antrum area returns to fasting size) of digestible solids was 355 ± 35 min in NUD patients versus 265 ± 20 min in controls (P < 0.001). The gastric emptying curve of digestible solids correlated with emptying of markers both in NUD patients (r = +0.96) and in controls (r = +0.93). Conclusions: The assessment of gastric clearance of radiopaque cylinders of 2 mm × 5 mm in size is a reliable tool for the study of gastric emptying rate of digestible solids. This is a readily available and easily performed test in any radiology unit.