Esophageal contractions, bolus transit and perception of transit after swallows of liquid and solid boluses in normal subjects

Changes in specific esophageal neuromechanical wall states are associated with conscious awareness of a solid swallowed bolus in healthy subjects

Esophageal neuromechanical wall states are the physical manifestations of circular muscle inhibition and contraction resulting from neural inputs and leading to bolus propulsion. A novel method infers esophageal neuromechanical wall states through simultaneous determination of pressure and diameter in vivo using impedance manometry. We hypothesized that changes in esophageal neuromechanical wall states relate to conscious awareness of esophageal bolus passage ("bolus perception"). Seven healthy participants were selected for perception of solid bolus passage and were compared with seven healthy participants with no conscious awareness of solid bolus passage. Participants were studied using impedance manometry (MMS Solar, Unisensor, 20 Hz). Subjects swallowed ten 5-ml liquid and ten 2-cm square saline-soaked bread boluses and rated bolus perception using a visual analog scale. Esophageal neuromechanical wall states were calculated and analyzed. Proportions of time spent in states with and without luminal distension were compared using a two-proportions Z-test. Bolus perception was associated with neuromechanical wall states corresponding to luminal distension more frequently than matching states without distension in the proximal esophagus (P < 0.001) and transition zone (P < 0.001), whereas there were no differences for the distal esophagus. In healthy volunteers, perceived swallows relate to changes in esophageal neuromechanical wall states in the proximal esophagus. We postulate that these changes relate to bolus retention and summation of active and passive wall tension activating intramural tension receptors.NEW & NOTEWORTHY This study explores esophageal neuromechanical wall states derived from changes in pressure and impedance-derived distension in relation to conscious awareness of esophageal solid bolus transit in healthy volunteers. There are increases in neuromechanical wall states indicative of esophageal distension in healthy volunteers with conscious awareness of bolus transit as compared with unaware individuals. Bolus-based esophageal distension is postulated as a mechanism for esophageal symptoms such as dysphagia.

ALTERED ESOPHAGEAL MOTILITY DURING PERCEPTION OF BOLUS TRANSIT IN HEALTHY VOLUNTEERS

BACKGROUND

The perception of bolus transit through the thoracic esophagus may be caused by altered esophageal anatomy and function.

OBJECTIVE

To evaluate the hypothesis that, in healthy volunteers, swallows followed by perception of esophageal bolus transit are associated with changes in esophageal motility.

METHODS

Simultaneous evaluation of motility and perception of esophageal bolus transit was performed in 22 healthy volunteers. Esophageal motility was evaluated by high-resolution manometry with a 32-channel solid state catheter. Each volunteer performed, in the sitting position, 10 swallows of a 5 mL bolus of saline and 10 swallows of pieces of 1 cm3 of bread, with an interval of at least 30 seconds between swallows. After each swallow the volunteers were asked about the perception of bolus transit through the esophagus.

RESULTS

Perception of bolus transit occurred in 11.7% of liquid swallows and in 48.1% of solid swallows. In liquid swallows the perception was associated with higher distal contractile integral and shorter proximal contraction length. Perception of solid bolus transit was associated with a longer distal latency, longer proximal contraction length, lower proximal contractile integral and shorter proximal contraction duration.

CONCLUSION

The perception of swallowed bolus transit through the esophagus in healthy individuals is more frequent with solid than liquid swallows and is associated with changes in proximal esophageal contractions.

ESOPHAGEAL MOTILITY IN MEN AND WOMEN EVALUATED BY HIGH-RESOLUTION MANOMETRY

BACKGROUND

Esophageal motility has been described in the literature as having differences between men and women. Most of these investigations use the water perfusion method for esophageal manometry. In this investigation the esophageal motility of men and women was compared with high-resolution manometry of the esophagus.

OBJECTIVE

To compare the esophageal motility of men and women with the high-resolution manometry method for esophageal manometry, performed in the sitting position. The hypothesis was that men and women have differences in esophageal motility.

METHODS

High-resolution manometry was performed in normal volunteers, 10 men [mean age: 37.5 (8.1) years] and 12 women [mean age: 38.7 (7.5) years], in the sitting position and with 10 swallows of a 5 mL bolus of saline, with an interval of at least 30 seconds between consecutive swallows. We evaluated the integrated relaxation pressure of the lower esophageal sphincter, contraction front velocity, distal contraction integral, distal latency, proximal contraction extension, proximal contraction duration >30 mmHg, proximal contraction duration, proximal contraction integral and maximal upper esophageal sphincter pressure.

RESULTS

There was no significant difference between men and women in the variables measured.

CONCLUSION

There was no difference in esophageal motility of men and women evaluated by the high resolution manometry method, in the sitting position with swallows of a liquid bolus.

Subclinical dysphagia in persons with Prader-Willi syndrome

Prader-Willi Syndrome (PWS) is caused by a genetic imprinting abnormality resulting from the lack of expression of the paternal genes at 15q11-q13. Intellectual disability, low muscle tone, and life-threatening hyperphagia are hallmarks of the phenotype. The need for the Heimlich maneuver, death from choking, and pulmonary infection occur in a disproportionally high number of persons with PWS. The widely held belief is that eating behaviors are responsible for choking and aspiration; yet, no investigation had sought to determine if swallowing impairments were present in persons with PWS. To address this research and clinical gap, simultaneous videofluoroscopy and nasal respiratory signals were used to record swallowing function and breathing/swallowing coordination in 30 participants with PWS. Subjects consumed thin liquid and barium cookies under two randomized conditions as follows: (i) controlled (cues to swallow and standardized bolus sizes); (ii) spontaneous (no cues or bolus size control). Under videofluoroscopy, the cohort showed disordered pharyngeal and esophageal swallowing in both conditions with disturbances in timing, clearance, and coordination of swallowing with the respiratory cycle. No participant showed a sensory response such as attempting to clear residue or coughing; thereby supporting the lack of overt symptoms. We conclude that the high death rate from choking and pulmonary infection in children and adults with PWS may be related, in part, to underlying, asymptomatic dysphagia. The combination of rapid eating and dysphagia would increase the risk of aspiration-related morbidity and mortality. © 2016 Wiley Periodicals, Inc.

Adapting human videofluoroscopic swallow study methods to detect and characterize dysphagia in murine disease models

This study adapted human videofluoroscopic swallowing study (VFSS) methods for use with murine disease models for the purpose of facilitating translational dysphagia research. Successful outcomes are dependent upon three critical components: test chambers that permit self-feeding while standing unrestrained in a confined space, recipes that mask the aversive taste/odor of commercially-available oral contrast agents, and a step-by-step test protocol that permits quantification of swallow physiology. Elimination of one or more of these components will have a detrimental impact on the study results. Moreover, the energy level capability of the fluoroscopy system will determine which swallow parameters can be investigated. Most research centers have high energy fluoroscopes designed for use with people and larger animals, which results in exceptionally poor image quality when testing mice and other small rodents. Despite this limitation, we have identified seven VFSS parameters that are consistently quantifiable in mice when using a high energy fluoroscope in combination with the new murine VFSS protocol. We recently obtained a low energy fluoroscopy system with exceptionally high imaging resolution and magnification capabilities that was designed for use with mice and other small rodents. Preliminary work using this new system, in combination with the new murine VFSS protocol, has identified 13 swallow parameters that are consistently quantifiable in mice, which is nearly double the number obtained using conventional (i.e., high energy) fluoroscopes. Identification of additional swallow parameters is expected as we optimize the capabilities of this new system. Results thus far demonstrate the utility of using a low energy fluoroscopy system to detect and quantify subtle changes in swallow physiology that may otherwise be overlooked when using high energy fluoroscopes to investigate murine disease models.

EFFECT OF SWALLOWED BOLUS VISCOSITY AND BODY POSITION ON ESOPHAGEAL TRANSIT, CONTRACTION AND PERCEPTION OF TRANSIT

Background The esophagus has a different response in relation to the characteristics of a swallowed bolus. Bolus viscosity and body position may affect esophageal contraction and transit. Objectives To investigate the effect of bolus viscosity and body position on esophageal contraction, transit and perception. Methods Esophageal contraction, transit and perception of transit were evaluated in 26 asymptomatic volunteers, 13 men and 13 women aged 18-60 years, mean: 33.6 (12.2) years. Esophageal contraction (manometry) and transit (impedance) were measured with a solid state catheter with sensors located 5, 10, 15, and 20 cm from the lower esophageal sphincter. Each volunteer swallowed in duplicate and in random sequence a 5 mL low viscous (LV) liquid bolus of an isotonic drink with pH 3.3, and a 5 mL high viscous (HV) paste bolus, which was prepared with 7.5 g of instant food thickener diluted in 50 mL of water (pH: 6.4). Results Total bolus transit time, in the sitting position, was longer with the HV bolus than with the LV bolus. Esophageal transit was longer in the supine position than in the sitting position. Bolus head advance time was longer with the HV bolus than with the LV bolus in both positions. Contraction esophageal amplitude was higher in the supine position than in the sitting position. The perception of bolus transit was more frequent with the HV bolus than with the LV bolus, without differences related to position. Conclusions The viscosity of the swallowed bolus and body position during swallows has an influence on esophageal contractions, transit and perception of transit.

Impedance as an adjunct to manometric testing to investigate symptoms of dysphagia: What it has failed to do and what it may tell us in the future

Dysphagia is a common reason for referral for investigations of oesophageal motility. Impedance measurement has now been incorporated into commercially available diagnostic manometry systems for more than a decade. This innovation, which offered the ability to record patterns of bolus transport without the need for simultaneous radiology, has for the most part failed to live up to expectations, offering few additional diagnostic insights. This review examines the potential pitfalls related to how impedance patterns are currently analysed and introduces and discusses the new concept of pressure-flow analysis integrating pressure and impedance measurements to derive new metrics linked to the pressures occurring within and around the bolus as it is being transported.

Combined impedance-manometry for the evaluation of esophageal disorders

PURPOSE OF REVIEW

Combined impedance-manometry was introduced just over 20 years ago for the assessment of esophageal motor function. Since then, technical developments have led to the introduction of high-resolution impedance-manometry (HRIM). However, analysis of the impedance and manometry recordings has remained separate and relatively unchanged since the introduction of HRIM, and it is unclear whether the addition of impedance has had a significant impact on the management of esophageal motor disorders.

RECENT FINDINGS

The major technical advance over the past 12 months or so has been the development of automated impedance-manometry (AIM) analysis, in which the impedance and manometric data are analyzed together to assess the interactions between pressure and flow. This analysis has revealed subtle abnormalities in esophageal function in patients with nonobstructive dysphagia who have normal manometry and conventional impedance analyses. AIM analysis has also revealed preoperative characteristics in patients that may predict the occurrence of postfundoplication dysphagia.

SUMMARY

Through ongoing technical development, impedance-manometry is becoming increasingly useful clinically to assess esophageal motility disorders as well as to provide further insights into esophageal physiology.

Esophageal motility in troublesome belching

CONTEXT

Supragastric belches are the main determinants of troublesome belching symptoms. In supragastric belches, air is rapidly brought into the esophagus and is immediately followed by a rapid expulsion before it has reached the stomach.

OBJECTIVE

To evaluate the esophageal contraction and transit after wet swallows in patients with troublesome belching.

METHODS

Esophageal contraction and transit were evaluated in 16 patients with troublesome belching and 15 controls. They were measured at 5, 10, 15, and 20 cm from the lower esophageal sphincter (LES) by a solid state manometric and impedance catheter. Each subject swallowed five 5 mL boluses of saline.

RESULTS

The amplitude, duration and area under the curve of contractions were similar in patients with troublesome belching and control subjects. The total esophageal bolus transit time was 6.2 (1.8) s in patients with troublesome belching and 6.1 (2.3) s in controls (P=0.55). The bolus presence time was longer in controls than in patients at 5 cm from the LES [controls: 6.0 (1.1) s, patients: 4.9 (1.2) s, P=0.04], without differences at 10, 15 and 20 cm from the LES. The bolus head advanced time was longer in patients than controls from 20 cm to 15 cm [controls: 0.1 (0.1) s, patients: 0.7(0.8)s, P=0.01] and from 15 cm to 10 cm [controls: 0.3 (0.1) s, patients: 1.6 (2.6) s, P=0.01] of the LES, without difference from 10 cm to 5 cm [controls: 0.7 (0.3) s, patients: 1.0 (1.1) s, P=0.37]. There was no difference in segment transit time.

CONCLUSION

There was no difference in esophageal contractions between patients with troublesome belching and controls. The swallowed bolus went slower into the proximal and middle esophageal body in patients than in control, but cross the distal esophageal body faster in patients than in controls.