Gastrointestinal function gastric emptying

Gastrointestinal sphincters are formed where the circular layer of smooth muscle is thickened. Sphincters occur at several points along the tract. Their function is to limit the movement of food materials from one region to another. For example, the pyloric sphincter found between the stomach and duodenum of the small intestine plays an important role in limiting the rate of gastric emptying. Sphincters undergo tonic contractions that may be sustained for minutes or hours. 

Figure 26-3. Patients with severe pancreatic exocrine insufficiency (n = 14, mean + SE) show marked alterations of gastrointestinal functions with shortened small bowel transit time, 90% gastric emptying time, and duration of the fed pattern. These alterations are corrected by enzyme replacement therapy ( P <. 05 vs. controls, P <. 05 vs. placebo) (Layer et al., 1997).

Moreover, recent studies suggest that gastric emptying and small intestinal transit are markedly accelerated in patients with untreated pancreatic insufficiency (Fig. 26-3) (Layer et al., 1997). The available time for digestion and absorption is therefore markedly decreased in these patients, which may contribute further to malabsorption. Disturbance of both digestion and gastrointestinal transit are corrected by enzyme replacement, suggesting that malabsorption is not only a consequence but also a cause of abnormal motor function. In turn, this... 

The peripheral effects concern the motility and tonus of gastrointestinal smooth muscle segmentation is enhanced but propulsive peristalsis is inhibited. The tonus of sphincter muscles is markedly raised (spastic constipation). The antidiarrhetic effect is used therapeutically (loperamide, p.180). Gastric emptying is delayed (pyloric spasm) and drainage of bile and pancreatic juice is impeded because the sphincter of Oddi contracts. Likewise, bladder function is affected specifically bladder emptying is impaired owing to an increased tone of the vesicular sphincter. 

The effects of nalbuphine and morphine on gastrointestinal function have been compared in 17 volunteers. Nalbuphine 10 mg prolonged gastric emptying to a greater extent than nalbuphine 5 mg or morphine 5 mg, which were about equal in their effects (9). However, another study (10) showed that nalbuphine produced significantly less inhibition of gastrointestinal activity than morphine. 

From the studies described above, it is evident that motilides not only stimulate gastric motility but also accelerate delayed gastric emptying in certain clinical conditions. As the next step, the clinical benefit to patients with gastrointestinal disorders (e.g., symptom relief) needs to be proved in double-blind and placebo-controlled studies. Motilides seem to offer an additional therapeutic possibility for the treatment of patients with impaired gastric motor function. 

Functional ultrasound of the gastrointestinal (GI) tract includes studies of the distal and proximal stomach, gastric and gallbladder emptying, gastric distribution, Gl wall motility, and flow of luminal contents in healthy subjects as well as in patients. Furthermore, it includes the effect of different meals and pharmacological intervention. 

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