Functional association between proximal and distal gastric motility during fasting and duodenal nutrient stimulation in humans

Impact of the Simulated Gastric Digestion Methodology on the In Vitro Intestinal Proteolysis and Lipolysis of Emulsion Gels

The aim of this work was to study the impact of the methodology of in vitro gastric digestion (i.e., in terms of motility exerted and presence of gastric emptying) and gel structure on the degree of intestinal proteolysis and lipolysis of emulsion gels stabilized by whey protein isolate. Emulsions were prepared at pH 4.0 and 7.0 using two homogenization pressures (500 and 1000 bar) and then the emulsions were gelled by heat treatment. These gels were characterized in terms of texture analysis, and then were subjected to one of the following gastric digestion methods: in vitro mechanical gastric system (IMGS) or in vitro gastric digestion in a stirred beaker (SBg). After gastric digestion, the samples were subjected to in vitro intestinal digestion in a stirred beaker (SBi). Hardness, cohesiveness, and chewiness were significantly higher in gels at pH 7.0. The degree of proteolysis was higher in samples digested by IMGS–SBi (7–21%) than SBg–SBi (3–5%), regardless of the gel’s pH. For SBg–SBi, the degree of proteolysis was not affected by pH, but when operating the IMGS, higher hydrolysis values were obtained for gels at pH 7.0 (15–21%) than pH 4.0 (7–13%). Additionally, the percentage of free fatty acids (%FFA) released was reduced by 47.9% in samples digested in the IMGS–SBi. For the methodology SBg–SBi, the %FFA was not affected by the pH, but in the IMGS, higher values were obtained for gels at pH 4.0 (28–30%) than pH 7.0 (15–19%). Our findings demonstrate the importance of choosing representative methods to simulate food digestion in the human gastrointestinal tract and their subsequent impact on nutrient bioaccessibility.

Gastroesophageal Reflux Disease and Foregut Dysmotility in Children with Intestinal Failure

Gastrointestinal dysmotility is a common problem in a subgroup of children with intestinal failure (IF), including short bowel syndrome (SBS) and pediatric intestinal pseudo-obstruction (PIPO). It contributes significantly to the increased morbidity and decreased quality of life in this patient population. Impaired gastrointestinal (GI) motility in IF arises from either loss of GI function due to the primary disorder (e.g., neuropathic or myopathic disorder in the PIPO syndrome) and/or a critical reduction in gut mass. Abnormalities of the anatomy, enteric hormone secretion and neural supply in IF can result in rapid transit, ineffective antegrade peristalsis, delayed gastric emptying or gastroesophageal reflux. Understanding the underlying pathophysiologic mechanism(s) of the enteric dysmotility in IF helps us to plan an appropriate diagnostic workup and apply individually tailored nutritional and pharmacological management, which might ultimately lead to an overall improvement in the quality of life and increase in enteral tolerance. In this review, we have focused on the pathogenesis of GI dysmotility in children with IF, as well as the management and treatment options.

The Effect of Gastrostomy Placement on Gastric Function in Children: a Prospective Cohort Study

BACKGROUND

A gastrostomy placement is frequently performed in pediatric patients who require long-term enteral tube feeding. Unfortunately, postoperative complications such as leakage, feeding intolerance, and gastroesophageal reflux frequently occur. These complications may be due to postoperative gastric dysmotility. Our aim was to evaluate the effect of gastrostomy placement on gastric emptying in children.

METHODS

A prospective study was performed including 50 children undergoing laparoscopic gastrostomy. Before and 3 months after gastrostomy, assessment was performed using the 13C-octanoic acid breath test, 24-h pH monitoring, and reflux symptom questionnaires.

RESULTS

Gastric half-emptying time significantly increased from the 57th to the 79th percentile (p < 0.001) after gastrostomy (p < 0.001). Fifty percent of patients with normal preoperative gastric emptying develop delayed gastric emptying (DGE, P > 95) after gastrostomy (p = 0.01). Most patients (≥75%) with leakage and/or feeding intolerance after gastrostomy had DGE after operation. A decrease in gastric emptying was associated with an increase in esophageal acid exposure time (r = 0.375, p < 0.001).

CONCLUSION

Gastrostomy placement in children causes a significant delay in gastric emptying. Postoperative DGE was associated with gastroesophageal reflux and was found in most patients with postoperative leakage and feeding intolerance. These negative physiologic effects should be taken into account when considering gastrostomy placement in children.

Motility disorders of the upper gastrointestinal tract in the intensive care unit: pathophysiology and contemporary management

Upper gastrointestinal (GI) dysmotility, an entity commonly found in the intensive care unit setting, can lead to insufficient nutrient intake while increasing the risk of infection and mortality. Further, overcoming the altered motility with early enteral feeding is associated with a reduced incidence of infectious complications in intensive care unit patients. Upper GI dysmotility in critical care patients is a common occurrence, and there are many causes for this problem, which affects a very heterogenous population with a multitude of underlying medical abnormalities. Therefore, it is of utmost importance to identify this widespread problem and subsequently institute a proper therapy as rapidly as possible. Prokinetic pharmacotherapies are currently the mainstay for the management of disordered upper GI motility. Future therapies, aimed at the underlying pathophysiology of this complex problem, are under investigation. These aim is to reduce the side effects of the currently available options, while improving on nutrition delivery in the critically ill. This review discusses the pathophysiology, clinical manifestations, diagnosis, and treatment of upper GI motility disturbances in the critically ill.

Current and future therapeutic prokinetic therapy to improve enteral feed intolerance in the ICU patient

Malnutrition is associated with poor outcomes in critically ill patients, and providing enteral feeding to those who cannot eat is considered best practice. Enteral feeding is often unsuccessful when there is delayed gastric emptying. Recent research has given additional insight into the mechanisms underlying delayed gastric emptying. Pharmacological strategies to improve the success of feeding include prokinetic drugs such as metoclopramide and erythromycin alone or in combination. When drug treatment fails, either parenteral nutrition or direct small intestinal feeding is indicated. Simpler methods to access the duodenum and distal small bowel for feed delivery are under investigation. This review summarizes current understanding of the mechanisms underlying enteral feeding intolerance in critical illness, together with the evidence for current treatment practices. Areas requiring further research are also described.

Effects and mechanisms of gastrointestinal electrical stimulation on slow waves: a systematic canine study

The aims of this study were to determine optimal pacing parameters of electrical stimulation on different gut segments and to investigate effects and possible mechanisms of gastrointestinal electrical stimulation on gut slow waves. Twelve female hound-mix dogs were used in this study. A total of six pairs of electrodes were implanted on the stomach, duodenum, and ascending colon. Bilateral truncal vagotomy was performed in six of the dogs. One experiment was designed to study the effects of the pacing frequency on the entrainment of gut slow waves. Another experiment was designed to study the modulatory effects of the vagal and sympathetic pathways on gastrointestinal pacing. The frequency of slow waves was 4.88 +/- 0.23 cpm (range, 4-6 cpm) in the stomach and 19.68 +/- 0.31 cpm (range, 18-22 cpm) in the duodenum. There were no consistent or dominant frequencies of the slow waves in the colon. The optimal parameters to entrain slow waves were: frequency of 1.1 intrinsic frequency (IF; 10% higher than IF) and pulse width of 150-450 ms (mean, 320.0 +/- 85.4 ms) for the stomach, and 1.1 IF and 10-20 ms for the small intestine. Electrical stimulation was not able to alter colon slow waves. The maximum entrainable frequency was 1.27 IF in the stomach and 1.21 IF in the duodenum. Gastrointestinal pacing was not blocked by vagotomy nor the application of an alpha- or beta-adrenergic receptor antagonist; whereas the induction of gastric dysrhythmia with electrical stimulation was completely blocked by the application of the alpha- or beta-adrenergic receptor antagonist. Gastrointestinal pacing is achievable in the stomach and small intestine but not the colon, and the maximal entrainable frequency of the gastric and small intestinal slow waves is about 20% higher than the IF. The entrainment of slow waves with gastrointestinal pacing is not modulated by the vagal or sympathetic pathways, suggesting a purely peripheral or muscle effect.

Pharmaceutical applications of AC biosusceptometry

AC Biosusceptometry offers an alternative to investigate noninvasively and without ionizing radiation the behavior of solid dosage forms in vitro and in the human gastrointestinal tract. This versatility allowed applying this technique in a wide field ranging from characterization of the disintegration process to elucidation of how the physiological parameters can interfere with pharmaceutical processes. It is increasingly important to understand how oral solid dosage forms behave in the human gastrointestinal tract. Once labelled, magnetic dosage forms provide an excellent opportunity to investigate complexes' interactions between dosage form and gastrointestinal physiology. In this paper, basic principles of this biomagnetic instrumentation and of the quantification based on magnetic images are reviewed. Also will be presented are some of the most recent applications of AC Biosusceptometry in the pharmaceutical research including oesophageal transit, gastric emptying and transit time of multiparticulate dosage forms, hydrophilic matrices and disintegration of tablets.

Diminished functional association between proximal and distal gastric motility in critically ill patients

OBJECTIVE

This study examined the effects of critical illness on the relationship between proximal and distal gastric motor activity during fasting and duodenal nutrient stimulation.

DESIGN

Prospective, case-controlled study.

PATIENTS AND PARTICIPANTS

Ten critically ill patients and ten healthy volunteers.

INTERVENTIONS

Concurrent proximal gastric (barostat) and antro-pyloro-duodenal (manometry) motility were recorded during fasting and during two 60-min duodenal nutrient infusions (Ensure at 1 kcal/min and 2 kcal/min) in random order, separated by a 2-h wash-out period.

RESULTS

Baseline proximal gastric volumes were similar between the two groups. At 10 min nutrient-induced fundic relaxation was lower in patients than healthy subjects (45 +/- 26 vs. 196 +/- 29 ml). In patients the frequency and volume amplitude of fundic waves were also lower. There were fewer propagated antral waves in patients than in healthy subjects during both fasting and nutrient infusion. These were more retrograde, shorter in length and associated with a pyloric contraction. The proportion of fundic waves followed by a distally propagated antral wave was significantly less in patients (0%, 0-8%) than controls 36% (11-44%).

CONCLUSIONS

In critical illness, in addition to impairment of proximal and distal gastric motor activity, the association between the two gastric regions is abnormal. This disturbance may interfere with meal distribution and further contribute to slow gastric emptying in these patients.