Bursts of non-deglutitive simultaneous contractions may be a normal oesophageal motility pattern

Motilin: from gastric motility stimulation to hunger signalling

After the discovery of motilin in 1972, motilin and the motilin receptor were studied intensely for their role in the control of gastrointestinal motility and as targets for treating hypomotility disorders. The genetic revolution - with the use of knockout models - sparked novel insights into the role of multiple peptides but contributed to a decline in interest in motilin, as this peptide and its receptor exist only as pseudogenes in rodents. The past 5 years have seen a major surge in interest in motilin, as a series of studies have shown its relevance in the control of hunger and regulation of food intake in humans in both health and disease. Luminal stimuli, such as bitter tastants, have been identified as modulators of motilin release, with effects on hunger and food intake. The current state of knowledge and potential implications for therapy are summarized in this Review.

Intestinal manometry: who needs it?

The use of manometry, i.e. the recording of pressures within hollow viscera, after being successfully applied to the study of esophageal and anorectal motor dysfunctions, has also been used to investigate physiological and pathological conditions of the small bowel. By means of this technique, it has been possible to understand better the normal motor functions of the small intestine, and their relationship and variations following physiologic events, such as food ingestion. Moreover, intestinal manometry has proved useful to document motor abnormalities of the small bowel, although recognition of altered patterns specific for a determinate pathologic condition is still unavailable. However, this technique often permits the detection of abnormal gut motility in patients with abdominal symptoms such as unexplained vomiting and diarrhea, and it is sometimes also useful to address therapeutic targeting.

Effect of clarithromycin on esophageal motility

As clarithromycin (CLA), an antibiotic commonly used for Helicobacter pylori eradication, stimulates gastroduodenal motility, we investigated whether it also stimulates esophageal motility. In 15 normal subjects, esophageal motility was recorded using a low-compliance manometric system with two ports in the esophageal body, one port in the lower esophageal sphincter (LES), and five ports in the antroduodenal tract to monitor the occurrence of phases I-III of the migrating motor complex. Thirty minutes after the occurrence of a duodenal phase III, we infused intravenously, randomly, and in a double-blind manner, CLA 100 mg in five subjects (group A), CLA 250 mg in five subjects (group B), and normal saline in the remaining five subjects (group C). LES tone and post-deglutitive residual pressure, as well as the amplitude and duration of the esophageal contractions, were measured each minute and averaged over a post-infusion period of 30 min. Both group A and B showed a LES tone significantly higher than that of group C after CLA infusion, whereas the post-deglutitive residual pressure was not significantly different from that of group C. The LES tone of group B was significantly higher than that of group A. Group B, but not group A, showed a wave amplitude and duration significantly higher than that of group C. In conclusion, CLA is able to stimulate LES tone and esophageal contractions with a dose-related effect.

Diurnal motor activities of the esophagus in conscious dogs

Diurnal motor activities of the upper, middle, and lower thirds of the thoracic esophagus, the lower esophageal sphincter, and the gastric body were recorded in six conscious dogs, using extraluminal force transducers. The motor activities of the thoracic esophagus and the lower esophageal sphincter were divided into three major motility patterns: feeding, digestive, and interdigestive. Each motility pattern was basically composed of repetitive bursts of contractions that were clearly classified into type I and II according to their contractile properties. Type I bursts were peristaltic contractions initiated at the upper thoracic esophagus and sequentially propagated distally to include the sphincter. Propagation velocity and duration of type I contractions were similar in all three motility patterns, and these contractions never were propagated into the stomach. Type II bursts were nonperistaltic simultaneous contractions of the thoracic esophagus and lower sphincter appearing synchronously with phase III of gastric interdigestive migrating contractions. Amplitude and duration of type II contractions were maximal at the sphincter, suggesting initiation at that site. In nonfeeding patterns, type I contractions would clear the esophagus of refluxed gastric contents, while type II contractions would prevent reflux.

Characterization of esophageal body and lower esophageal sphincter motor function in the very premature neonate

OBJECTIVES

To characterize esophageal body and lower esophageal sphincter (LES) motor function in very premature infants.

STUDY DESIGN

Esophageal manometry was performed in 12 very premature infants of 26 to 33 weeks' postmenstrual age (PMA) (body weights of 610-1360 g). Esophageal motor patterns were recorded for 30 minutes with a perfused micromanometric sleeve assembly (outer diameter, 2.0 mm).

RESULTS

Esophageal pressure waves triggered by dry swallows were predominantly (84%) peristaltic in propagation sequence. All infants showed tonic LES contraction; the mean resting LES pressure (LESP) for individual infants ranged from 5.0 +/- 4.1 mm Hg to 20.0 +/- 4.8 mm Hg. In all infants the LES relaxed (duration, 5.8 +/- 3.0 seconds; nadir pressure, 1.8 +/- 2.6 mm Hg) in response to pharyngeal swallows. Transient LES relaxations (TLESRs) (duration, 21.7 +/- 8.7 seconds; nadir pressure, 0.1 +/- 1.8 mm Hg) occurred on average 2.6 +/- 1.6 times per study; 86% of these relaxations triggered esophageal body common cavity events known to be associated with gastroesophageal reflux.

CONCLUSIONS

Esophageal motor function is well developed in very premature infants. Our data also suggest that TLESR is the predominant mechanism of reflux in these babies.

Normal esophageal body function: a study using ambulatory esophageal manometry

OBJECTIVE

The objective of this study was to establish normative ambulatory manometric data for contractions and contraction propagation in three levels of the esophagus.

METHODS

Twenty-five healthy volunteers underwent simultaneous ambulatory 24 h manometry. Concomitant 24 h pH studies were performed to exclude the presence of increased esophageal acid exposure. Pressures were recorded over a complete circadian cycle while patients continued with their normal lifestyles including eating and sleeping. Data were analyzed with a software program that was previously modified and validated and that enables quantitation of contractions in terms of efficacy.

RESULTS

The frequency of contractions was lowest during sleep, was increased when awake, and was highest during meals. Contraction amplitude increased during meals, providing a greater propulsive force for bolus transport. Similarly, the prevalence of peristaltic waves varied according to different physiologic states, ie., while eating, upright, awake, and sleeping. An increased amplitude and prevalence of peristalsis resulted in an increase in manometric efficacy during meals.

CONCLUSIONS

This study provides normative data for ambulatory manometry for comparison when studying patients with disease.

Distal oesophageal motility characteristics in relation to amplitude of contraction in healthy persons

OBJECTIVES

We wanted to supply a new 'vertical' approach in the analysis of oesophageal contraction data by describing variables of oesophageal function in relation to the amplitude of contraction.

METHODS

Twenty-four-hour oesophageal manometry was performed in 20 healthy volunteers (11 women and 9 men; mean age, 47.5 years). Computer analysis was performed in pressure windows at 10, 15, 20, 30, 40, 50, 60, 70, and 80 mm Hg. Within each window two variables were extracted: the distribution (%) of peristaltic contractions and median duration (sec) of contractions.

RESULTS

The percentage of peristaltic contractions increased with increasing amplitude of contractions during the upright position (15-20 mm Hg window: mean (+/- SD) 68.2% (+/- 13.3%), versus 70-80 mm Hg window: 85.0% (+/- 13.0%) (P < 0.001)) and meal periods (66.9% (+/- 13.8%) versus 92.2% (+/- 11.2%) (P < 0.001)) but not in the supine position (75.9% (+/- 14.6%) versus 73.5% (+/- 16.1%) (P = 0.64)). Contraction duration diminished with increasing contraction amplitude (upright, 15-20 mm Hg window: 3.2 sec (+/- 1.5 sec) versus 70-80 mm Hg window: 1.5 sec (+/- 1.0 sec) ( P < 0.0001); meal: 3.8 sec (+/- 1.7 sec) versus 1.9 sec (+/- 1.1 sec) (P < 0.01); supine: 4.1 sec (+/- 3.0 sec) versus 2.2 (+/- 1.5 sec) (P = 0.03)). The percentage of peristaltic contraction was lower during the supine periods than during meals and upright periods at high amplitudes (70-80 mm Hg window; P < 0.05). The number of contractions decreased linearly on a logarithmic scale with pressure window amplitude.

CONCLUSIONS

Pressure wave amplitude and organization were closely related. Accurate base-line determination and delineation are critical for the interpretation of oesophageal manometric recordings.

Increase of swallows before onset of phase III of migrating motor complex in normal human subjects

The aim of our study was to analyze the relation between the deglutitive activity and fasting esophageal and gastric motility in normal subjects. Fifteen healthy subjects (9 males, 6 females) with a mean age of 42 years (range 19-65) were studied. A 24-hr pH-manometric recording was performed using a probe with four solid-state recording sites 10 cm apart, placed so as to record the motor activity of esophageal body, lower esophageal sphincter (LES) or distal part of the esophagus, and gastric antrum. An additional probe with one recording site was placed in the pharynx to evaluate swallowing. A pH electrode was also placed at 5 cm above the sphincter. Data were transferred to a personal computer and analyzed using specific software. Subjects received two meals during the recording session. MMCs were almost exclusively recorded during the nighttime. A mean of 2 +/- 0.94 (SD) MMC per subject was detected with a mean (+/- SD) interval, between each cycle, of 86.11 +/- 34.53 min. During the 30 min preceding gastric phase III, the number of swallows showed an increase that reached statistical significance 5 min before the onset of phase III. A similar pattern was observed for the area under the curve (AUC) of the esophagus and LES. In conclusion deglutition and esophageal motility vary with the MMC, suggesting that the deglutitive activity is part of the interdigestive motility pattern.

Automatic detection of esophageal pressure events. Is there an alternative to rule-based criteria?

Ambulatory long-term motility recording is used increasingly for evaluation of esophageal function. The enormous amount of motility data recorded by this method demands subsequent computer analysis. One of the most crucial steps of this analysis becomes the process of automatic selection of relevant pressure peaks at the various recording levels. Until now, this selection has been performed entirely by rule-based systems, requiring each pressure deflection to fit within predefined rigid numerical limits in order to be detected. However, due to great variations in the shapes of the pressure curves generated by muscular contractions, rule-based criteria do not always select the pressure events most relevant for further analysis. We have therefore been searching for a new concept for automatic event recognition. The present study describes a new system, based on the method of neurocomputing. A large sample of normal esophageal pressure deflections was used as a "learning set," and the performance of the trained neural networks was subsequently verified on different sets of data from normal subjects. Our trained networks detected pressure deflections with sensitivities of 0.79-0.99 and accuracies of 0.89-0.98, depending on the recording level within the esophageal lumen. The neural networks often recognized peaks that clearly represented true contractions but that had been rejected by a rule-based system. We conclude that neural networks have potentials for automatic detections of esophageal, and possibly also other kinds of gastrointestinal, pressure variations.