Prediction of Acrylonitrile-Butadiene-Styrene Mechanical Properties through Compressed-Sensing Techniques.

One of the challenges in the plastic industry is the cost and time spent on the characterization of different grades of polymers. Compressed sensing is a data reconstruction method that combines linear algebra with optimization schemes to retrieve a signal from a limited set of measurements of that signal. Using a data set of signal examples, a tailored basis can be constructed, allowing for the optimization of the measurements that should be conducted to provide the highest and most robust signal reconstruction accuracy. In this work, compressed sensing was used to predict the values of numerous properties based on measurements for a small subset of those properties. A data set of 21 fully characterized acrylonitrile-butadiene-styrene samples was used to construct a tailored basis to determine the minimal subset of properties to measure to achieve high reconstruction accuracy for the remaining nonmeasured properties. The analysis showed that using only six measured properties, an average reconstruction error of less than 5% can be achieved. In addition, by increasing the number of measured properties to nine, an average error of less than 3% was achieved. Compressed sensing enables experts in academia and industry to substantially reduce the number of properties that must be measured to fully and accurately characterize plastics, ultimately saving both costs and time. In future work, the method should be expanded to optimize not only individual properties but also entire tests used to simultaneously measure multiple properties. Furthermore, this approach can also be applied to recycled materials, of which the properties are more difficult to predict.

Effect of pancreatic polypeptide on gastric accommodation and gastric emptying in conscious rats.

Pancreatic polypeptide (PP) is an anorexigenic hormone released from pancreatic F cells upon food intake. We aimed to determine the effect of PP on gastric accommodation and gastric emptying in conscious Wistar HAN rats to investigate whether effects on motor function could contribute to its anorexigenic effects. Intragastric pressure (IGP) was measured through a chronically implanted gastric fistula during the infusion of a nutrient meal (Nutridrink; 0.5 ml/min). Rats were treated with PP (0, 33 and 100 pmol·kg(-1)·min(-1)) in combination with N(G)-nitro-L-arginine methyl ester (L-NAME; 180 mg·kg(-1)·h(-1)), atropine (3 mg·kg(-1)·h(-1)), or vehicle. Furthermore, the effect of PP was tested after subdiaphragmal vagotomy of the stomach. Gastric emptying of a noncaloric and a caloric meal after treatment with 100 pmol·kg(-1)·min(-1) PP or vehicle was compared using X-rays. PP significantly increased IGP during nutrient infusion compared with vehicle (P < 0.01). L-NAME and atropine significantly increased IGP during nutrient infusion compared with vehicle treatment (P < 0.005 and 0.01, respectively). The effect of PP on IGP during nutrient infusion was abolished in the presence of L-NAME and in the presence of atropine. In vagotomized rats, PP increased IGP compared with intact controls (P < 0.05). PP significantly delayed gastric emptying of both a noncaloric (P < 0.05) and a caloric (P < 0.005) meal. PP inhibits gastric accommodation and delays gastric emptying, probably through inhibition of nitric oxide release. These results indicate that, besides the well-known centrally mediated effects, PP might decrease food intake through peripheral mechanisms.

Clinical validation of the VIPUN™ gastric monitoring system versus manometry for the evaluation of gastric motility.

BACKGROUND: Gastrointestinal dysmotility is frequently suspected in patients with gastroparesis, functional dyspepsia, and ileus, and in the intensive care unit. Monitoring of gastric motility in clinical practice remains challenging. A novel technology was developed to meet the medical need for a widely available bedside tool to monitor gastric motility continuously. The VIPUN™ Gastric Monitoring System (GMS) comprises a nasogastric feeding tube with intragastric balloon to allow for measuring gastric contractions. AIMS: To compare the performance of the VIPUN GMS versus a reference technique (manometry). METHODS: In this validation study in healthy subjects, the investigational catheter and a solid-state manometry catheter were placed in the stomach concomitantly. Motility was recorded for 2.5 h: 2 h in a fasting state, followed by a 400-kcal liquid meal, and monitoring of the fed state for the remaining half hour. The performance of both systems was compared by automated recognition and manual identification of the contractile activity. Data are presented as mean (standard deviation). KEY RESULTS: The analysis set comprised 13 healthy subjects (6 women, age: 27.5 (8.1) years, BMI: 22.2 (2.46) kg/m2). Automatically-recognized contractility was strongly correlated between the two techniques (endpoint: contraction duration; Spearman ρ = 0.96, p < 0.001). A correlation was also observed between the number of individual contractions identified by expert gastroenterologists on both technologies independently (ρ = 0.71, p = .007) and between the contractions identified by the experts and by the GMS software (ρ = 0.87, p = 0.001). No serious or unanticipated adverse events occurred. CONCLUSIONS & INFERENCES: The observed strong correlations with the gold standard, manometry, validate the performance of the VIPUN GMS as a gastric monitoring system.

The relation between symptom improvement and gastric emptying in the treatment of diabetic and idiopathic gastroparesis.

OBJECTIVES: The relationship between symptom improvement (SI) and acceleration of gastric emptying (GE) for different drugs used in the treatment of idiopathic and diabetic gastroparesis is uncertain. In this paper we examined the study-specific correlations between SI and GE, and we performed a meta-regression analysis of the association across multiple studies. METHODS: The MEDLINE database (1,946 to present) was searched, and only controlled trials or trials with an established effective comparator that compared both SI and GE were included. RESULTS: Studies were identified for metoclopramide (n=6), domperidone (n=6), cisapride (n=14), erythromycin (n=3), botulinum toxin (n=2), and levosulpiride (n=3). Even though most drugs concomitantly improved symptoms and accelerated GE, no study reported a significant correlation between SI and GE. Moreover, a correlation analysis over all studies using meta-regression did not show a significant relationship between SI and GE. Our findings need to be qualified by inconsistencies in study methods, which is a limitation but also suggests that our findings are robust to methodological factors. CONCLUSIONS: In this review, no evidence of a relationship between SI and GE was identified for different drugs used for the treatment of gastroparesis. This finding questions the use of GE measurement to direct drug development for gastroparesis.

Do prokinetic agents provide symptom relief through acceleration of gastric emptying? An update and revision of the existing evidence.

BACKGROUND: Gastroparesis and functional dyspepsia are disorders characterized by upper gastrointestinal symptoms and multifaceted etiologies. One of the main therapeutic approaches is accelerating gastric emptying (GE) by means of prokinetic agents. Their efficacy has been demonstrated, although the association between symptom improvement and acceleration of emptying is less clear. Meta-analyses have found contradictory results. Differences in applied methodology and included trials might drive these contradictions. OBJECTIVE: To provide a transparent meta-analysis update to elucidate the association between symptom improvement and acceleration of GE due to gastroprokinetic agents available for long-term use in patients with gastroparesis. DESIGN: Two approaches from earlier meta-analyses were executed and compared. One analyzed the relative changes on active treatment versus baseline, the other compared the change from baseline on active treatment versus the change from baseline on placebo. Papers that reported sufficient numerical data for both analyses were selected. Both analyses included the same trials. RESULTS: Overall, both approaches yield the same positive direction of association between symptom improvement and acceleration of emptying (0.291 (-0.391, 0.972), p = 0.4 and 0.453 (0.123, 0.782), p = 0.007 for the active-only and placebo-controlled analysis respectively). The association between symptom improvement and GE acceleration for studies using optimal GE tests was either 0.028 (p > 0.9) or 0.463 (p = 0.007), and for sub-optimal GE tests was either 0.370 (p = 0.4) or 0.052 (p > 0.9) depending on the used meta-analysis methodology. CONCLUSIONS: The applied methodology for GE testing, and the meta-analysis substantially impacts the conclusion. When considering the clinically relevant outcome of improvement from baseline, symptoms and emptying improve with prokinetics, but no correlation is found between both aspects. When the change over placebo is considered, limiting the analysis to scientifically more rigorous study approaches, changes in emptying rate and symptom improvement are positively associated.

Efficacy of buspirone, a fundus-relaxing drug, in patients with functional dyspepsia.

BACKGROUND & AIMS: Impaired accommodation and hypersensitivity to gastric distention are believed to be involved in the development of functional dyspepsia (FD). Buspirone, a 5-hydroxytryptamine 1A receptor agonist, relaxes the proximal stomach in healthy individuals. We studied the effects of buspirone on symptoms and mechanisms of FD. METHODS: We performed a randomized, double-blind, placebo-controlled, crossover study of 17 patients (13 women; mean age, 38.5 ± 2.4 years). The study included 2 treatment periods of 4 weeks each, separated by a 2-week washout period. In the first period, 7 participants were given buspirone (10 mg, 3 times daily for 4 weeks) and 10 were given placebo 15 minutes before meals; patients switched groups for the second period. We assessed meal-related symptoms and severity, along with gastric sensitivity, accommodation, and emptying (by using barostat and breath tests) before and after 4 weeks of treatment. RESULTS: Buspirone significantly reduced the overall severity of symptoms of dyspepsia (7.5 ± 1.3 vs 11.5 ± 1.2 for placebo; P < .005) and individual symptoms of postprandial fullness, early satiation, and upper abdominal bloating, whereas placebo had no significant effect (all P < .05). Buspirone did not alter the rate of gastric emptying of solids or sensitivity to gastric distention, but it significantly increased gastric accommodation, compared with placebo (229 ± 28 vs 141 ± 32 mL, respectively; P < .05), and delayed gastric emptying of liquids (half-life = 64 ± 5 vs 119 ± 24 minutes, respectively). Adverse events were similar when patients were given buspirone or placebo. CONCLUSIONS: In patients with FD, 4 weeks of administration of buspirone significantly improved symptoms and gastric accommodation, compared with placebo, whereas gastric emptying of liquids was delayed.

New Stent Technologies.

Ureteral stents are an indispensable part of any (endo-) urologic practice. Despite the widely demonstrated advantages of stents, they also carry a considerable risk of side effects and complications, such as urinary symptoms, pain, hematuria, decreased quality of life, stent-related infection, and encrustation. Multiple pathways in preventing or mitigating these side effects and complications and improving stent efficacy have been and are being investigated, including stent architecture and design, biomaterials, and coatings. This article provides an update on currently researched and available stents as well as future perspectives.

Functional dyspepsia.

PURPOSE OF REVIEW: This review summarizes the recent progress in the epidemiology, pathophysiology and treatment of functional dyspepsia. RECENT FINDINGS: Epidemiological, pathophysiological and therapeutic studies continue to examine the Rome III-proposed subdivision of functional dyspepsia into epigastric pain syndrome and postprandial distress syndrome. Although epidemiological studies support the subdivision, studies in patient samples show major overlap. Several studies identified overlapping functional disorders and psychosocial comorbidity as major contributors to the severity of functional dyspepsia and its impact on quality of life. Central processing of visceral stimuli, and its role in the pathogenesis of functional dyspepsia, as well as low-grade inflammation in the duodenum are important emerging topics in pathophysiology research. Therapeutic studies have reported on prokinetic and fundus-relaxing drugs. Acotiamide is a first-in-class drug with both prokinetic and fundus-relaxing properties that was evaluated in the recent phase 2 and phase 3 trials in functional dyspepsia. SUMMARY: There is gradual progress in our understanding of the symptom pattern, impact and pathophysiology of functional dyspepsia. The areas of recent advances including the recognition of low-grade duodenal inflammation, central nervous system processing and the exploration of novel pharmacotherapeutic approaches are summarized in this review.

Emerging drugs for functional dyspepsia.

INTRODUCTION: Functional dyspepsia (FD) is a highly prevalent condition with a major impact on quality of life and high socio-economic and healthcare costs. To date, no treatment of established efficacy in FD is available. AREAS COVERED: This review of the literature summarizes recent progress in drug development for FD. Gastroprokinetics are considered therapeutically relevant in FD, although it has been difficult to prove symptomatic benefit. Recently studied drugs include 5-HT(4) receptor agonists (tegaserod), motilin receptor agonists (GSK962040 and others) and ghrelin receptor agonists (TZP-101, TZP-102). Fundic relaxant drugs are a novel approach to FD therapy. Recently studied drugs include 5-HT(1A) receptor agonists (buspirone, tandospirone, R137696) and acotiamide (or Z-338 or YM443), a first-in-class muscarinic M(1)/M(2) receptor antagonist and cholinesterase inhibitor. Extensive Phase II studies support the potential efficacy of acotiamide, especially for postprandial distress syndrome. In refractory cases, psychotropics are considered and recently studied agents include venlafaxine, which in a large multi-center study did not confirm efficacy, and a combination preparation of flupenthixol/melitracen, which showed potential efficacy in a small study. EXPERT OPINION: While many new prokinetic drugs are in the early stages of evaluation, acotiamide emerges as the drug with a promising efficacy profile. Convincing evidence for the efficacy of psychotropics is lacking.

Erythromycin stimulates phasic gastric contractility as assessed with an isovolumetric intragastric balloon pressure measurement.

BACKGROUND: A novel technique to assess gastric motility by measuring the pressure in a low-volume intragastric balloon was developed to monitor (disordered) motility. We previously showed that this technique allows measuring pharmacologically induced inhibition of motility. In this study, we assessed whether it is possible to measure pharmacologically induced stimulation of gastric motility using 200 mg erythromycin. Erythromycin is a highly effective stimulator of gastric emptying and contractility. METHODS: After an overnight fast, a nasogastric balloon catheter was introduced in healthy subjects. After inflation with 120 ml of air, the catheter was connected to a pressure sensor. Intraballoon pressure was continuously recorded for 4 h. After a baseline recording of 2 h, 200 mg erythromycin was infused intravenously over 20 min while the recording continued for 2 h. Epigastric symptoms were surveyed on 100-mm visual analogue scales. Motility was quantified from the pressure recording as a gastric balloon motility index. Wilcoxon signed-rank tests were performed. Data are shown as median (interquartile range). KEY RESULTS: Six subjects were enrolled and five completed the procedures (age: 28 (25-29) years, body mass index: 24.0 (23.8-24.5) kg m-2 ). One subject could not tolerate tube placement. Bloating, nausea, and epigastric sensation scores were 0 (0-3), 0 (0-1), and 1 (0-1) mm, respectively. Erythromycin significantly increased the motility index from 0.48 (0.41-0.51) to 0.79 (0.70-0.82) (p = 0.03). CONCLUSIONS AND INFERENCES: Gastric motility assessed via pressure measurement in a low-volume intragastric balloon is able to detect pharmacologically stimulated motility in healthy subjects, which further validates this technique.

Supraphysiological effects of pancreatic polypeptide on gastric motor function and nutrient tolerance in humans.

Pancreatic polypeptide (PP) is known to affect food intake. In this exploratory study, we set out to investigate its supraphysiological effect on food tolerance, gastric accommodation, and emptying. In 12 healthy volunteers, 0, 3, or 10 pmol*kg-1 *min-1 PP was administered intravenously (PP0, PP3 or PP10). Thirty minutes thereafter, nutrient drink infusion (60 ml*min-1 ) through a nasogastric feeding tube was started until maximum satiation. Gastric accommodation was assessed by measuring the intragastric pressure (IGP; nasogastric manometry). In a separate test, the effect of PP0 or PP10 on gastric emptying was tested in 10 healthy volunteers and assessed using the 13 C breath test. Results are presented as mean ± SEM, and p < 0.05 was considered significant. For the IGP test, PP increased ingested nutrient volume: 886 ± 93, 1059 ± 124, and 1025 ± 125 ml for PP0, PP3, and PP10, respectively (p = 0.048). In all groups, Nadir IGP values were reached upon food intake (transformed values: 1.5 ± 0.2, 1.7 ± 0.3, and 1.6 ± 0.3 mmHg for PP0, PP3, and PP10, respectively; NS) to return to baseline thereafter. For the gastric emptying study, volunteers ingested a similar nutrient volume: 802 ± 119 and 1089 ± 128 ml (p = 0.016), and gastric half-emptying time was 281 ± 52 and 249 ± 37 min for PP0 and PP10, respectively (NS). No significant correlation between tolerated nutrient volume and IGP drop (R² < 0.01; p = 0.88 for PP0 vs. PP3 and R² =0.07; p = 0.40 for PP0 vs. PP10, respectively) or gastric half-emptying time (R² = 0.12; p = 0.32) was found. A supraphysiological PP dose enhances food tolerance; however, this effect is not mediated through gastric motility. CLINICAL TRIAL REGISTRY NUMBER: NCT03854708 is obtained from clinicaltrials.gov.

Continuous Assessment of Gastric Motility and Its Relation to Gastric Emptying in Adult Critically Ill Patients.

BACKGROUND: Critically ill patients frequently develop feeding intolerance, which is difficult to predict. In healthy subjects, gastric motility, assessed by nasogastric balloon tube, correlated with gastric emptying. We now investigated this correlation in critically ill patients, as well as the feasibility and safety of such application in a pilot study. METHODS: Endotracheally intubated adults scheduled to receive enteral nutrition (EN) were included. After insertion of a double-lumen nasogastric balloon tube and radiographic confirmation of position, balloon pressure was recorded for 10 hours after inflation (4 hours fasted, 2 hours during administration of 13 C-labeled EN, and 4 hours postprandially). Gastric motility was expressed as Gastric Balloon Motility Index (GBMI), reflecting the fraction of time in which phasic gastric contractions occurred. Gastric emptying was assessed by 13 C-octanoate breath test and expressed as gastric half-emptying time (GET½). Correlation between GBMI (assessed in different time intervals) and GET½ was investigated by Pearson/Spearman correlation. Feasibility was defined as the success of tube placement and pressure recording. Safety was assessed based on adverse device effects. RESULTS: Thirty patients were enrolled, of whom 19 had paired GBMI and GET½ data. There was no correlation between GBMI and GET½. The tube was successfully placed in 28/30 (93.3%) patients. In 3/28 (10.7%) patients, balloon leakage precluded analysis. Two safety events were directly linked to the device. CONCLUSION: This pilot study showed no significant correlation between balloon-assessed gastric motility and emptying in critically ill patients. The feasibility/safety profile of the balloon tube appears similar to that of standard nasogastric tubes.

Effect of protein composition of enteral formula on gastric content volume during continuous feeding: A randomized controlled cross-over study in healthy adults.

BACKGROUND & AIMS: Enteral nutrition with polymeric intact protein formula is the preferred medical nutrition strategy in critically ill patients when oral intake is insufficient. Enteral nutrition formulas are often rich in casein protein, which has coagulating properties. Coagulation in the stomach impedes gastric emptying and might result in high gastric residual volumes which are a clinical sign of gastrointestinal intolerance and a major reason to decrease or to discontinue enteral feeding. In this study the impact of protein composition of enteral formula on gastric content volume (GCV) during and after continuous feeding was tested in healthy volunteers in whom gastrointestinal conditions of critically ill patients were mimicked. METHODS: An enteral formula including 4 proteins (P4) with non-coagulating properties was compared to a casein-dominant formula (Cas) with coagulating properties. Esomeprazole and codeine were administered to mimic stress ulcer prophylaxis and induce gastroduodenal motor dysfunction, both being hallmarks of critically ill patients. GCV was measured with magnetic resonance imaging during and after continuous enteral feeding (100 mL/h for 4h) in a randomized single-center cross-over study. Results are provided as mean (SD). Significance level of p < 0.05 was applied. RESULTS: Twenty subjects completed the study (14 women, 6 men, 25.8 (4.6) years old, BMI: 22.5 (1.5) kg/m2). The GCV as change from baseline at T = 240 (primary endpoint) did not differ between study products (P4: 124.3 (83.4) vs. Cas: 137.1 (102.0) mL, 95% CI: -57.4, 27.0, p = 0.457). During feeding and after cessation of feeding, the area under the GCV-curve (AUC0-360 GCV) for P4 and Cas was 44631.1 (15546.1) and 52822.2 (19686.1) mL∗min, respectively (p = 0.061). During feeding the GCV was lower at T = 180 min (175.4 (64.8) vs. 205.2 (75.4) mL, p = 0.038) and after cessation of feeding at T = 300 min (81.3 (71.1) vs. 116.3 (84.3) mL, p = 0.004) and T = 330 min (39.9 (53.9) vs. 73.6 (81.1) mL, p = 0.031). With P4 it took less time to reach half of the GCV at T = 240 min compared to Cas (52.8 (27.6) vs. 65.4 (29.9) min, p = 0.020). CONCLUSIONS: In this study in which healthy volunteers received esomeprazole and codeine to mimic gastrointestinal conditions of critically ill patients, observations of secondary endpoints suggest faster gastric emptying with P4 compared to Cas, and less gastric accumulation, possibly due to the non-coagulating properties of the P4 protein blend. Considering the small effect and the possible clinical relevance of reduced intragastric accumulation of enteral nutrition, the potential impact of protein coagulation should be further investigated in relevant study populations. Registered under Netherlands Trial Register identifier no. NTR6423.

Gastric accumulation of enteral nutrition reduces pressure changes induced by phasic contractility in an isovolumetric intragastric balloon.

BACKGROUND: An isovolumetric intragastric balloon to continuously measure gastric phasic contractility was recently developed by us. We aimed to investigate the readout of this technique in relation to gastric content and gastric emptying. METHODS: In this crossover investigation, the VIPUNTM Gastric Monitoring System, which comprises a double lumen nasogastric feeding tube with integrated intragastric balloon, was used to assess phasic gastric contractility by interpretation of the pressure in an isovolumetric balloon in 10 healthy subjects. Balloon pressure was recorded in fasted state, during a 2-hour intragastric nutrient infusion (1 kcal/ml at 25, 75, or 250 ml/h) and 4 hours post-infusion, and quantified as Gastric Balloon Motility Index (GBMI), ranging from 0 (no contractility) to 1 (maximal contractility). Gastric accumulation was quantified with magnetic resonance imaging and gastric emptying with a13 C-breath test. Results are expressed as mean(SD). KEY RESULTS: GBMI was significantly lower during infusion at 250 ml/h compared to baseline (0.13(0.05) versus 0.46(0.12)) and compared to infusion at 25 (0.54(0.21)) and 75 ml/h (0.43(0.20)), all P < 0.005. Gastric content volume was larger after infusion at 250 versus 75 ml/h (P < 0.001). Half-emptying time and accumulation were both negatively correlated with postprandial contractility. Postprandial GBMI was significantly lower when GCV>0 ml compared to when the stomach was empty. CONCLUSIONS AND INFERENCES: Enteral nutrition dose-dependently decreased the contractility readout. This decrease was linked to gastric accumulation of enteral nutrition.

Gastroduodenal motility.

PURPOSE OF REVIEW: Abnormalities of gastroduodenal motility are considered key players in the pathogenesis of upper gastrointestinal symptoms in disorders such as functional dyspepsia and gastroparesis. Abnormalities of sensory control are considered another important factor that contributes to symptom generation. This review summarizes recent progress in our understanding of gastroduodenal motility and sensitivity in health and in disease. RECENT FINDINGS: Although gastric and small intestinal motility remain an important focus of research, including the application of the SmartPill (SmartPill Corp., Buffalo, New York, USA) wireless motility monitoring capsule, duodenal sensitivity and low-grade duodenal inflammation are new areas of interest in the pathogenesis of functional dyspepsia. A number of genetic polymorphisms associated with functional dyspepsia are being investigated, but large-scale studies are still lacking. Central processing of visceral stimuli, and its role in the pathogenesis of functional dyspepsia, is another important emerging topic. Therapeutic studies have reported on novel pharmacological approaches in functional dyspepsia and gastroparesis, as well as gastric electrical stimulation in the treatment of refractory gastroparesis. SUMMARY: There is gradual progress in our understanding of the pathogenesis of gastroduodenal symptoms. Areas of recent advances including the recognition of low-grade duodenal inflammation, the role of central nervous system processing in visceral hypersensitivity and the exploration of novel pharmacotherapeutic approaches.

Effect of muscarinic and nicotinic receptor antagonism on rat gastric motor activity.

BACKGROUND/AIMS: Our aim was to investigate whether muscarinic and nicotinic receptors mediate nitric oxide release during motor events in the rat stomach. METHODS: Isolated rat stomach volume changes were monitored in an organ bath setup with an intragastric balloon coupled to a barostat and studied in basal conditions and during electrical vagal stimulation (EVS). In conscious rats, the intragastric pressure (IGP) was measured during test meal infusion. RESULTS: In the presence of N(G)-nitro-L-arginine methyl ester (L-NAME; 0.1 mmol/l), EVS induced significant gastric contractions (mean +/- SEM = 0.27 +/- 0.04 ml; n = 6) that could be blocked by atropine (3 micromol/l) and hexamethonium (0.1 mmol/l). In the presence of atropine and/or hexamethonium, EVS-induced relaxations could not be blocked by L-NAME, while exogenous nitric oxide could still relax the stomach. In conscious rats, atropine (1 mg kg(-1)) initially decreased IGP, while during further distension it increased IGP. In the presence of L-NAME (30 mg kg(-1)) atropine consistently decreased IGP. L-NAME alone significantly increased IGP during the test meal infusion, but this effect was reduced in the presence of atropine. CONCLUSION: These findings indicate a role for nicotinic and muscarinic receptors in the vagal-stimulation-induced activation of nitrergic nerves in the rat stomach.

Repeated Gastric Motility Measurement Affects Gastric Motility and Epigastric Symptom Sensation.

Background: Gastric motility is an important determinant of gastric emptying, epigastric symptom generation, and intolerance to food. Motility is classically assessed directly using manometry or an intragastric balloon. These diagnostic methods are perceived as stressful and invasive, which, by itself might influence the readout of these assessments. Our hypothesis was that with repeated exposure to an invasive motility test the outcome would be different. Methods: Gastric motility was assessed with a custom-made orogastric balloon catheter in 10 healthy subjects naive to intubation. A motility index ranging from 0 (no motility) to 1 (maximum motility) was calculated in the fasted state for 3.5 h. Symptoms were surveyed with visual analog scales of 100 mm. Results are presented as median (interquartile range). Results: Motility index during visit 1 [0.40 (0.37-0.59)] was lower compared to visit 2 [0.50 (0.45-0.66); not significant] and 3 [0.63 (0.50-0.71); p = 0.016]. Nausea and pain scores were significantly higher during visit 1 (35 (2.8-126) and 103 (88-125) mm, respectively) compared with visit 3 [1 (2.8-26) mm (p = 0.016) and 75 (30-100) mm (p = 0.008), respectively]. No adverse events were observed. Conclusions: Repeated exposure to an invasive method to assess motility resulted in more vigorous motility and lower symptom scores. Caution is warranted when interpreting functional assessments, as prior exposure to invasive tests might confound the obtained results through habituation.

Codeine delays gastric emptying through inhibition of gastric motility as assessed with a novel diagnostic intragastric balloon catheter.

BACKGROUND: The use of opioids as analgesic is on the rise, despite their inhibitory effect on gastric emptying. A novel feeding catheter with integrated intragastric balloon was developed to continuously assess gastric motility, enabling to investigate the effect of opioids on motility and emptying simultaneously. We aimed to discriminate normal and pharmacologically impaired gastric motility and its impact on gastric emptying in healthy adults. METHODS: The VIPUN Gastric Monitoring System comprises a nasogastric balloon catheter and a monitoring unit. In a four-way randomized, single-blinded, cross-over study, subjects received either placebo or 58.8 mg codeine phosphate in combination with either an uninflated or an inflated (180 mL) balloon catheter. Motility-induced pressure changes were recorded for 6 hours. During the first 2 hours, nutrients were infused (225 kcal, 75 mL/h). Gastric emptying was assessed with a 13 C-octanoate breath test and expressed as gastric half-emptying time (GET½). An algorithm, designed to detect phasic contractility, converted pressure changes to a gastric balloon motility index (GBMI). Results are presented as mean(SD). KEY RESULTS: Eighteen subjects completed the investigation (32(13) years, 22(2) kg/m2 ). After codeine, GBMI was lower (0.31(0.16)) and GET½ was longer (233(57) minutes) compared with placebo (GBMI: 0.48(0.15), P < .01 and GET½: 172(12) minutes, P < .001). Within-subject ΔGET½ correlated significantly with ΔGBMI (r = -0.77 and P < .001). CONCLUSIONS AND INFERENCES: The VIPUN Gastric Monitoring System allowed to assess gastric motility safely and continuously. The correlation between pharmacologically decreased gastric emptying and motility indicates a strong link between both. Gastric motility, measured with this innovative device, can be an indicator for gastrointestinal intolerance.