'Efficacy' of esophageal peristalsis: a manometric parameter to quantify esophageal body dysfunction

Circadian clocks in the digestive system

Many molecular, physiological and behavioural processes display distinct 24-hour rhythms that are directed by the circadian system. The master clock, located in the suprachiasmatic nucleus region of the hypothalamus, is synchronized or entrained by the light-dark cycle and, in turn, synchronizes clocks present in peripheral tissues and organs. Other environmental cues, most importantly feeding time, also synchronize peripheral clocks. In this way, the circadian system can prepare the body for predictable environmental changes such as the availability of nutrients during the normal feeding period. This Review summarizes existing knowledge about the diurnal regulation of gastrointestinal processes by circadian clocks present in the digestive tract and its accessory organs. The circadian control of gastrointestinal digestion, motility, hormones and barrier function as well as of the gut microbiota are discussed. An overview is given of the interplay between different circadian clocks in the digestive system that regulate glucose homeostasis and lipid and bile acid metabolism. Additionally, the bidirectional interaction between the master clock and peripheral clocks in the digestive system, encompassing different entraining factors, is described. Finally, the possible behavioural adjustments or pharmacological strategies for the prevention and treatment of the adverse effects of chronodisruption are outlined.

WHAT IS THE REAL IMPAIRMENT ON ESOPHAGEAL MOTILITY IN PATIENTS WITH GASTROESOPHAGEAL REFLUX DISEASE?

Context Impairment of esophageal motility is a common finding in patients with gastroesophageal reflux disease (GERD) as reduced lower esophageal sphincter (LES) basal pressure. A very low LES pressure might facilitate the occurrence of more gastroesophageal reflux whereas abnormal esophageal peristalsis may contribute to impaired esophageal clearance after reflux. Objective Evaluate the esophageal motor function of the lower esophageal sphincter and esophageal body in the various forms of gastroesophageal reflux disease. Methods The manometrics records of 268 patients, who had evaluation of the esophageal motility as part of the diagnostic gastroesophageal reflux disease were split into four groups, as follows: 33 patients who had no esophagitis; 92 patients who had erosive esophagitis; 101 patients who had short Barrett's esophagus and 42 patients who had long Barrett's esophagus. Results The group who had long Barrett's esophagus showed smaller mean LES pressure and higher percentage of marked LES hypotonia; in the distal segment of the esophageal body the this group showed higher percentage of marked hypocontractility of the distal segment (<30 mm Hg); this same group showed higher percentage of esophageal motility disorders. Conclusions The most intense esophageal motility disorders and lower pressure of lower esophageal sphincter were noted in the group with long Barrett's esophagus. Those with reflux esophagitis and short Barrett's esophagus had esophageal motility impairment, intermediate among patients with esophagitis and long Barrett's esophagus. Patients with typical symptoms of gastroesophageal reflux but without esophagitis by endoscopy study showed no impairment of esophageal motility.

Gastrointestinal physiology and digestive disorders in sleep

PURPOSE OF REVIEW

The dynamic interplay of the digestive system and sleep is an excellent example of brain-body interaction. New advances in measuring techniques provide an opportunity to evaluate physiology that is dependent upon the sleep/wake state or circadian rhythm and potentially differentiate between normal and pathological conditions.

RECENT FINDINGS

Sleep-related changes in gastrointestinal physiology create vulnerabilities to digestive issues such as reflux, whereas disorders such as duodenal ulcers raise the importance of circadian variations in digestive system function. Advances in the area of normal sleep physiology have furthered our understanding of the underlying cause of irritable bowel syndrome, and the mechanisms by which sleep disruption may aggravate inflammatory bowel disease. Additionally, important early work has shown that the treatment of digestive disorders such as reflux can improve sleep quality just as the improvement in sleep may aid in the treatment of digestive disorders.

SUMMARY

For the clinician, these forward steps in our knowledge mark the start of an era in which understanding the effects of the sleep/wake state and circadian rhythms on gastrointestinal physiology promise to yield novel diagnostic and therapeutic opportunities.

Clinical correlates of dysphagia to oesophageal dysmotility: studies using combined manometry and impedance

This study aimed to elucidate the mechanism of dysphagia by determining the simultaneous relationships between subjective perception of swallow with oesophageal motility and bolus transport in patients with non-obstructive dysphagia (NOD). Combined oesophageal manometry and impedance was performed in 18 consecutive NOD patients and 14 healthy controls. Swallow was abnormal if the amplitude of distal oesophageal contractions was less than 30 mmHg or simultaneous contractions occurred. Bolus transit was abnormal if bolus exit was not found at one or more of the measuring sites. Perception of each swallow was assessed using a standardized scoring system and was enhanced if score was >1. The prevalence of complete bolus transit was lower in NOD patients compared with healthy controls (P = 0.001). Abnormal liquid bolus transit was found in 40% of patients with normal motility and 38% of patients with abnormal motility, whereas abnormal viscous bolus transit was observed in 38% of patients with normal motility and 70% of patients with abnormal motility. Agreement between enhanced perception and impedance was poor during liquid (kappa = 0.12, 95% CI: -0.003 to 0.233) and viscous swallowing (kappa = 0.12, 95% CI: -0.004 to 0.244). Agreement between enhanced perception and manometry was even poorer during liquid (kappa = -0.16, 95% CI: -0.302 to 0.022) and viscous swallowing (kappa = -0.12, 95% CI: -0.25 to 0.002). NOD patients show poor correlation between dysphagia and oesophageal motility parameters. The results suggest that, in patients with NOD, oesophageal motor dysfunction may play a limited role, if any, in the generation of dysphagia.

Ingestible capsule for impedance and pH monitoring in the esophagus

Twenty-four-hour ambulatory pH monitoring is an essential tool for diagnosing gastroesophageal reflux disease (GERD). Simultaneous impedance and pH monitoring of the esophagus improves the detection and characterization of GERD. Conventional catheter-based monitoring systems are uncomfortable and interfere with the normal activity of the patient. To overcome these disadvantages, different wireless esophageal monitoring systems have been proposed. A capsule containing sensors for impedance and pH monitoring with wireless communication capabilities is presented. A low cost miniature microcontroller was utilized for interfacing between the sensors and a wireless transmitter. The microcontroller program allowed efficient management of the electric power provided by a 3-V battery. Magnetic holding is proposed as an alternative to surgical affixation of the monitoring capsule. Permanent neodymium magnets separated by 27 cm successfully held the capsule in a test tube. Experimental results demonstrated that friction force can aid magnetic holding to overcome peristalsis. The proposed design efficiently detected acid and nonacid reflux. More research regarding the holding method and capsule packaging are necessary to optimize the mechanical performance of the proposed design in order to facilitate clinical testing on human subjects.

Friction-assisted magnetic holding of an ingestible capsule for esophageal pH and impedance monitoring

24-hour catheter-based ambulatory pH and impedance monitoring is an essential tool for diagnosing esophageal disorders. However, catheter-based monitoring systems are uncomfortable and interfere with normal activities of the patient. To overcome these disadvantages, different wireless monitoring systems have been proposed. However, efficient ways to position and hold wireless capsules are lacking. Currently there is a need to develop safe and reliable methods to hold an esophageal wireless monitoring system in position for 24 hours. Friction-assisted magnetic holding is proposed as an alternative to conventional holding techniques. Permanent magnet and electromagnet designs with the required characteristics to achieve this task were computer-designed and simulated. The size and power requirements of the magnets were considered. Simulation results were verified using laboratory experiments. Permanent neodymium magnets offered the best performance for the intended application. The obtained results show the feasibility of friction-assisted magnetic holding for esophageal monitoring. Improvements to the thread design, friction enhancing pins, magnetic shielding and encapsulation methods are necessary for in vivo testing.