Intrabolus pressure gradient identifies pathological constriction in the upper esophageal sphincter during flow

An analytical and comparative study of swallowing in a tumor-infected oesophagus: a mathematical model

This study discusses non-steady effects encountered in peristaltic flows in oesophagus. The purpose of this communication is to evolve a mechanism to diagnose tumor in an oesophagus mathematically. The tumor is modelled by generic bump function of certain height and width. The method of solution follows long wavelength and low-Reynolds number approximations for unsteady flow, while integrations have been performed numerically in order to plot graphs, which reveal various characteristics of the flow. The goal is to assess how pressure varies across the tumor's width. The spatial, as well as temporal, dependence of pressure has been studied in the laboratory frame of reference. The pressure distribution for tumor-infected oesophagus is compared with that of normal oesophagus. An intensified pressure is obtained in the presence of tumor. The interruption while swallowing through benign oesophageal tumor is confirmed by an abrupt pressure rise across the tumor's width. Tumor position also plays a significant role whether it is at contraction or relaxation of walls. Additionally, wall-shear-stress, volumetric flow rate and streamlines have also been described and compared with that without tumor growth. The expressions corresponding to all the physical quantities are computed numerically. Further, this model may also be implemented to the two-dimensional channel flow for an industrial application.

A Short History of High-Resolution Esophageal Manometry

High-resolution esophageal manometry (HRM) utilizes sufficient pressure sensors such that intraluminal pressure is monitored as a continuum along luminal length, similar to time viewed as a continuum on polygraph tracings in 'conventional' manometry. When HRM is coupled with pressure topography plotting, and pressure amplitude is transformed into spectral colors with isobaric areas indicated by same-colored regions, "Clouse plots" are generated. HRM has several advantages compared to the technology that it replaced: (1) the contractility of the entire esophagus can be viewed simultaneously in a uniform standardized format, (2) standardized objective metrics of peristaltic and sphincter function can be systematically applied for interpretation, and (3) topographic patterns of contractility are more easily recognized with greater reproducibility. Leveraging these advantages led to the current standard for the interpretation of clinical esophageal HRM studies, the Chicago Classification (CC), now in its fourth iteration. Compared to conventional manometry, HRM has vastly improved the sensitivity for detecting achalasia, largely due to the objectivity and accuracy of identification of impaired esophagogastric junction (EGJ) relaxation. Additionally, it has led to the subcategorization of achalasia into three clinically relevant subtypes, differentiated by the contractile function of the esophageal body, and identified an additional disorder of EGJ outflow obstruction wherein esophageal peristalsis is preserved. Headway has also been made in understanding hypocontractile and hypercontractile conditions. In summary, HRM and the CC process have revolutionized our understanding of esophageal motility and motility disorders. Moving forward, there will always be remaining challenges, but we now have the tools to meet them.

Toward a robust swallowing detection for an implantable active artificial larynx: a survey

Total laryngectomy consists in the removal of the larynx and is intended as a curative treatment for laryngeal cancer, but it leaves the patient with no possibility to breathe, talk, and swallow normally anymore. A tracheostomy is created to restore breathing through the throat, but the aero-digestive tracts are permanently separated and the air no longer passes through the nasal tracts, which allowed filtration, warming, humidification, olfaction, and acceleration of the air for better tissue oxygenation. As for phonation restoration, various techniques allow the patient to talk again. The main one consists of a tracheo-esophageal valve prosthesis that makes the air passes from the esophagus to the pharynx, and makes the air vibrate to allow speech through articulation. Finally, swallowing is possible through the original tract as it is now isolated from the trachea. Yet, many methods exist to detect and assess a swallowing, but none is intended as a definitive restoration technique of the natural airway, which would permanently close the tracheostomy and avoid its adverse effects. In addition, these methods are non-invasive and lack detection accuracy. The feasibility of an effective early detection of swallowing would allow to further develop an implantable active artificial larynx and therefore restore the aero-digestive tracts. A previous attempt has been made on an artificial larynx implanted in 2012, but no active detection was included and the system was completely mechanic. This led to residues in the airway because of the imperfect sealing of the mechanism. An active swallowing detection coupled with indwelling measurements would thus likely add a significant reliability on such a system as it would allow to actively close an artificial larynx. So, after a brief explanation of the swallowing mechanism, this survey intends to first provide a detailed consideration of the anatomical region involved in swallowing, with a detection perspective. Second, the swallowing mechanism following total laryngectomy surgery is detailed. Third, the current non-invasive swallowing detection technique and their limitations are discussed. Finally, the previous points are explored with regard to the inherent requirements for the feasibility of an effective swallowing detection for an artificial larynx. Graphical Abstract.

Transient hypopharyngeal intrabolus pressurization patterns: Clinically relevant or normal variant?

INTRODUCTION

In oropharyngeal dysphagia, impaired pharyngoesophageal junction (PEJ) opening is reflected by an elevated hypopharyngeal intrabolus pressure (IBP), quantifiable using pharyngeal high-resolution manometry with impedance (P-HRM-I). Transient intrabolus pressurization (TP) phenomena are not sustained and last for only a brief period. We hypothesized that TP patterns reflect impaired coordination between timing of hypopharyngeal bolus arrival and PEJ relaxation.

METHODS

A retrospective audit was conducted of P-HRM-I datasets; 93 asymptomatic Controls and 214 Patients with differing etiological/clinical backgrounds were included. TP patterns were examined during 10ml liquid swallows. TP was defined by a simultaneous, non-sustained, pressurization wave spanning from the velo-/meso-pharynx to PEJ. The coordination between deglutitive pharyngeal bolus distension and PEJ relaxation timing was assessed using timing variables; (i) Distention-Contraction Latency (DCL, s) and (ii) PEJ Relaxation Time (RT, s). Resultant flow resistance was quantified (IBP, mmHg).

RESULTS

TP swallows were observed in 87 (28%) cases. DCL was not significantly different in relation to TP, while PEJ relaxation time was shorter, and IBP was higher during TP swallows. In Patients RT-DCL time difference correlated with IBP (r -0.368, p < 0.01).

CONCLUSION

Bolus distension and PEJ relaxation were miss-timed during TP swallows, impeding bolus flow and leading to a brief period of pressurization of the pharyngeal chamber by muscular propulsive forces. While TP swallows were identified in both Controls and Patients, increased IBPs were most apparent for Patient swallows indicating that the extent of IBP increase may differentiate pathological TP swallows.

Annular Flow in the Upper Esophageal Sphincter Demonstrated with Dynamic 320-row Area Detector Computed Tomography

Understanding bolus flow patterns in swallowing (rheology, the study of flow) is fundamental to assessment and treatment of dysphagia. These patterns are complex and poorly understood. A liquid swallow is typically biphasic, including air, so the actual bolus has both liquid and gas phases. We report a novel observation of annular two-phase flow (a ring of liquid around a core of air) as thin liquids passed through the upper esophageal sphincter (UES). Dynamic CT was performed on 27 healthy asymptomatic volunteers swallowing liquid barium in a semi-reclining position. Each subject swallowed 3, 10, and 20 ml of either thin (14 subjects) or thick liquid (13 subjects). Sagittal and axial images were analyzed. Flow patterns in the UES were assessed on cross-sectional images. Annular flow was seen in the majority of subjects with thin liquid but few with thick liquid swallows. The percentage of Annular flow during UES opening was 3 ml 58%, 10 ml 58%, 20 ml 56% in thin and 3 ml 0%, 10 ml 4%, 20 ml 1% in thick. Annular flow was usually observed from the second or third frames after onset of UES opening. The other pattern, Plug flow was seldom seen with thin but was typical with thick liquid swallows. Annular flow was the most common pattern for thin liquids (but not thick liquids) passing through the UES. Annular flow has been defined as a liquid continuum adjacent to the channel wall with a gas continuum (core) in the center of the channel. The two regions are demarcated by a gas–liquid interface. Annular flow is typical for two-phase gas–liquid flow in a vertical or inclined channel. It results from the interaction of viscosity with cohesive and adhesive forces in the two phases. We infer that the difference in flow pattern between thin liquid–air and thick liquid–air boluses resulted from the differing magnitudes of viscous forces.

Biomechanical correlates of sequential drinking behavior in aging

BACKGROUND

The timed water swallow test (TWST) is a test of sequential swallowing where a measured volume is ingested as quickly as comfortably possible. We undertook a study of the biomechanics underpinning the TWST in healthy young and older participants.

METHODS

Thirty healthy volunteers underwent high-resolution impedance manometry (MMS; Unisensor, 2.7 mm diameter, 32 pressure sensors, 16 impedance segments). Participants were asked to drink 150 mL, 0.9% normal saline solution rapidly. Swallowing biomechanics and bolus flow characteristics were assessed using pressure-flow analysis and compared using t test and Fisher's exact test with significance as P < .05.

KEY RESULTS

Older participants (n = 18; 76 ± 11 years) took longer to complete the TWST (21.2 ± 2.5 vs 9.2 ± 1.0 seconds; P < .001) and displayed reduced volume per swallow (16.6 ± 1.3 vs 27.8 ± 2.9 mL; P < .001) compared to younger participants (n = 12; 29 ± 5 years). Two distinctive pharyngeal swallowing patterns were observed: (a) a single rapid sequence of swallows with or without a clearing swallow (Pattern I) or (b) multiple, shorter sequences interrupted and/or interspersed with single swallows or breaks (Pattern II). Some older participants showed biomechanical evidence of upper esophageal sphincter restriction (n = 7) or impaired deglutitive inhibition (n = 7), associated with the more prolonged Pattern II (TWST duration 30.1 ± 1.5 vs Pattern I 11.9 ± 1.5 seconds; P < .001).

CONCLUSIONS AND INFERENCES

Healthy older participants had an increased duration of TWST, suggesting a need to adapt normative values for this population. Rapid sequential swallowing was associated with evidence of UES restriction and impaired deglutitive inhibition in some older participants.

Modulation of pharyngeal swallowing by bolus volume and viscosity

Oropharyngeal swallowing involves complex neuromodulation to accommodate changing bolus characteristics. The pressure events during deglutitive pharyngeal reconfiguration and bolus flow can be assessed quantitatively using high-resolution pharyngeal manometry with impedance. An 8-French solid-state unidirectional catheter (32 pressure sensors, 16 impedance segments) was used to acquire triplicate swallows of 3 to 20 ml across three viscosity levels using a Standardized Bolus Medium (SBMkit) product (Trisco, Pty. Ltd., Australia). An online platform (https://swallowgateway.com/; Flinders University, South Australia) was used to semiautomate swallow analysis. Fifty healthy adults (29 females, 21 males; mean age 46 yr; age range 19-78 yr old) were studied. Hypopharyngeal intrabolus pressure, upper esophageal sphincter (UES) maximum admittance, UES relaxation pressure, and UES relaxation time revealed the most significant modulation effects to bolus volume and viscosity. Pharyngeal contractility and UES postswallow pressures elevated as bolus volumes increased. Bolus viscosity augmented UES preopening pressure only. We describe the swallow modulatory effects with quantitative methods in line with a core outcome set of metrics and a unified analysis system for broad reference that contributes to diagnostic frameworks for oropharyngeal dysphagia.NEW & NOTEWORTHY The neuromodulation of the healthy oropharyngeal swallow response was described in relation to bolus volume and viscosity challenges, using intraluminal pressure and impedance topography methods. Among a wide range of physiological measures, those indicative of distension pressure, luminal opening, and flow timing were most significantly altered by bolus condition, and therefore can be considered to be potential markers of swallow neuromodulation. The study methods and associated findings inform a diagnostic framework for swallow assessment in patients with oropharyngeal dysphagia.

Effects of Posture and Swallow Volume on Esophageal Motility Morphology and Probability of Bolus Clearance: A Study Using High-Resolution Impedance Manometry

The Chicago classification diagnostic criteria of esophageal motility disorders are based on 5-ml water swallows in the supine position and have not been analyzed for the correlation between the morphology and bolus transit in the upright position and larger volume swallow conditions. This study aimed to evaluate the effect of posture and swallow volume on peristaltic morphology and the probability of bolus clearance in patients with nonspecific esophageal disorder. A total of 139 patients (4,214 swallows) were included for high-resolution impedance manometry analysis in the right lateral recumbent and upright positions, as well as 5- and 10-ml liquid swallows. Intact peristalses were more frequent in the right lateral recumbent position than in the upright position. No difference was reported on failed peristalsis between both positions. Breaks were more frequent in the upright position. A 20 mmHg isobaric contour (compared with 30 mmHg) was associated with decreased bolus clearance. Bolus clearance probability with 10-ml swallows is greater than that with 5-ml swallows. There was no significant difference in the total bolus clearance comparing between the right lateral recumbent and upright positions. The right lateral recumbent position was associated with a higher intact peristalsis. The volume of swallow did not affect the integrality of esophageal peristalsis but did improve the bolus clearance.

[High-resolution manometry of pharyngeal swallowing dynamics]

BACKGROUND

To transport a bolus from the mouth into the stomach, regular contraction of the pharyngeal muscles and a coordinated function of the upper esophageal sphincter (UES) are necessary. The muscle contraction generates intraluminal pressure, which pushes the bolus continuously forward. In contrast to imaging studies, manometric methods enable assessment of intraluminal pressure buildup and the function of the muscles involved. These methods were initially established for the esophagus and have been used increasingly in the pharynx for 7-8 years. Pharyngeal high-resolution manometry (pHRM) allows pressure measurements in high spatial and temporal resolution, and assessment of pharyngeal swallowing dynamics.

OBJECTIVE

An overview is given of the implementation, evaluation, and interpretation of the pHRM data, as well as of the current state of research.

MATERIALS AND METHODS

PubMed and Scopus were searched for the keywords "high-resolution manometry" and "pharynx" or "upper esophageal sphincter". Original articles, reviews, and book chapters on the subject pHRM were included.

RESULTS

Swallowing pressure conditions in the pharynx and the UES can be assessed by pHRM. The spatiotemporal pressure plot gives an overview of changes in pharyngeal motor function. Determination of swallowing parameters enables a sophisticated evaluation of swallowing; a comparison with normal values permits delimitation of pathologies.

CONCLUSION

Although several swallowing parameters still need to be further evaluated for clinical routine, a pHRM study should nowadays always be carried out for a comprehensive evaluation of the swallowing process.

Systematic Review of Pharyngeal and Esophageal Manometry in Healthy or Dysphagic Older Persons (>60 years)

We undertook a systematic review of swallowing biomechanics, as assessed using pharyngeal and esophageal manometry in healthy or dysphagic older individuals aged over 60 years of age, comparing findings to studies of younger participants. PRISMA-P methodology was used to identify, select, and evaluate eligible studies. Across studies, older participants had lower upper esophageal sphincter (UES) resting pressures and evidence of decreased UES relaxation when compared to younger groups. Intrabolus pressures (IBP) above the UES were increased, demonstrating flow resistance at the UES. Pharyngeal contractility was increased and prolonged in some studies, which may be considered as an attempt to compensate for UES flow resistance. Esophageal studies show evidence of reduced contractile amplitudes in the distal esophagus, and an increased frequency of failed peristaltic events, in concert with reduced lower esophageal sphincter relaxation, in the oldest subjects. Major motility disorders occurred in similar proportions in older and young patients in most clinical studies, but some studies show increases in achalasia or spastic motility in older dysphagia and noncardiac chest pain patients. Overall, study qualities were moderate with a low likelihood of bias. There were few clinical studies specifically focused on swallowing outcomes in older patient groups and more such studies are needed.

The critical importance of pharyngeal contractile forces on the validity of intrabolus pressure as a predictor of impaired pharyngo-esophageal junction compliance

INTRODUCTION

Restrictive defects of the pharyngo-esophageal junction (PEJ) are common in both structural and neurological disorders and are amenable to therapies aiming to reduce outflow resistance. Intrabolus pressure (IBP) acquired with high-resolution manometry and impedance (HRMI) is an indicator of resistance and a marker of reduced PEJ compliance. Constraints and limitations of IBP as well as the optimal IBP parameter remain undefined.

AIMS

To determine: (i) the impact of peak pharyngeal pressure (PeakP) on the diagnostic accuracy of IBP for the detection of a restrictive defect at the PEJ and (ii) the optimal IBP parameter for this purpose.

METHODS

In 52 dysphagic patients previously treated for head and neck cancer. Five candidate IBP measures and PeakP were obtained with HRMI, as well as a presence of a stricture determined by a mucosal tear after endoscopic dilatation. Predictive values of IBP measures were evaluated by receiver operating characteristic (ROC) analysis for all patients and reiterated as patients with lowest PeakP were progressively removed from the cohort.

RESULTS

All IBP parameters had fair to good accuracy at predicting strictures. Intrabolus pressure measured at a discrete point of maximum admittance 1 cm above the maximal excursion of the upper esophageal sphincter had highest sensitivity (0.76) and specificity (0.78). When PeakP was at least 57 mm Hg both sensitivity and specificity improved to 0.9.

CONCLUSIONS

Pharyngeal propulsive force has substantial impact on the accuracy of IBP as a predictor of a PEJ stricture. When PeakP is ≥57 mm Hg, an elevated IBP is highly predictive of a restrictive defect at the PEJ.

Roles of High-resolution Manometry in Predicting Incomplete Bolus Transit in Patients With Dysphagia

BACKGROUND

High-resolution manometry (HRM) is used to assess esophageal motility diseases. Abnormalities in a number of HRM parameters have been reported in patients with dysphagia. However, it is unclear whether some of abnormal HRM parameters are predictive of dysphagia. The aim of this retrospective study was to investigate the roles of HRM parameters in predicting incomplete bolus clearance (IBC) in patients with dysphagia using high-resolution impedance manometry.

METHODS

A total of 644 wet swallows were reviewed and analyzed in 63 patients with symptoms of dysphagia or reflux who underwent a clinical high-resolution impedance manometry test. IBC was defined based on impedance measurement. The relationship of each of abnormal HRM parameters with IBC was analyzed and their roles in predicting IBC were determined.

RESULTS

Patients with symptoms of both dysphagia and reflux showed the highest IBC rate, and patients with symptoms of reflux had the lowest IBC rate. The IBC was more prevalent in the distal esophagus. Premature contractions and peristalsis with large breaks were associated with a higher IBC rate in the proximal esophagus (P<0.05); large breaks, ineffective peristalsis, and abnormalities of the esophageal gastric junction functions were associate with higher IBC rates in the distal esophagus (P<0.05). Abnormalities in a number of motility parameters were able to predict IBC with high specificities and/or high sensitivity, such as pan esophageal pressurization, ineffective peristalsis, and large breaks. Abnormal integrative relaxation pressure of the lower esophageal sphincter with concurrent pan esophageal pressurization, ineffective peristalsis, or large breaks is predictive of IBC with nearly 100% of specificity.

CONCLUSIONS

Abnormalities in a number of HRM parameters are not only useful in diagnosing esophageal motility diseases, but also valuable in predicting IBC during swallowing.

Clinical measurement of gastrointestinal motility and function: who, when and which test?

Symptoms related to abnormal gastrointestinal motility and function are common. Oropharyngeal and oesophageal dysphagia, heartburn, bloating, abdominal pain and alterations in bowel habits are among the most frequent reasons for seeking medical attention from internists or general practitioners and are also common reasons for referral to gastroenterologists and colorectal surgeons. However, the nonspecific nature of gastrointestinal symptoms, the absence of a definitive diagnosis on routine investigations (such as endoscopy, radiology or blood tests) and the lack of specific treatments make disease management challenging. Advances in technology have driven progress in the understanding of many of these conditions. This Review serves as an introduction to a series of Consensus Statements on the clinical measurements of gastrointestinal motility, function and sensitivity. A structured, evidence-based approach to the initial assessment and empirical treatment of patients presenting with gastrointestinal symptoms is discussed, followed by an outline of the contribution of modern physiological measurement on the management of patients in whom the cause of symptoms has not been identified with other tests. Discussions include the indications for and utility of high-resolution manometry, ambulatory pH-impedance monitoring, gastric emptying studies, breath tests and investigations of anorectal structure and function in day-to-day practice and clinical management.

Effect of Body Position on Pharyngeal Swallowing Pressures Using High-Resolution Manometry

The effect of body position and gravitational pull on the complex pressure-driven process of pharyngeal swallowing remains unknown. Using high-resolution manometry (HRM), this study aims to identify positional adaptations of pharyngeal physiology by evaluating swallowing pressure patterns in a series of inverted body positions. Ten healthy adults each underwent swallowing tasks with pharyngeal HRM at six body positions using an inversion table (0°[upright], 45°, 90°[supine], 110°, 135°, and 180°[fully inverted]). Repeated measures ANOVA was used to assess impact of position on pressure parameters, and pharyngeal-UES pressure gradients translate. Velopharyngeal pressures varied by position (P < 0.001), with significantly higher pressures generated with inversion ≥90°, compared with upright and 45°. Change in position did not significantly affect common mesopharyngeal pressures or swallowing pressure durations. UES valving mechanisms were preserved during inversion, with subtle variations observed in integral pressures (P = 0.011). Pharyngeal-UES pressure gradients changed with position (P < 0.01), increasing with inversion > 90° compared to upright and 45°. Mechanisms of deglutition may differ with position and relative direction of gravity, particularly when at > 45° inclination. Increased palatal pressure is generated in the upside-down position to achieve nasopharyngeal closure and prevent regurgitation. While other classically measured pressures may not consistently differ with positioning, many individuals exhibit adaptations in pressure gradients when inverted, likely due to a combination of changes in pharyngeal driving force and UES opening mechanisms. Identification of these changes, relative to position, further builds on our understanding of the adaptability of the pharyngeal swallowing system.

Consistency and effect of body position change on measurement of upper and lower esophageal sphincter geometry using impedance planimetry in a canine model

The EndoFLIP (Endolumenal Functional Lumen Imaging Probe, Crospon Inc, Galway, Ireland) device uses the technique of impedance planimetry to evaluate dimensions and distensibility of the upper and lower esophageal sphincter. The null hypotheses for this study were that EndoFLIP variables would be stable between anesthestic episodes and would not be affected by body position when evaluating the upper and lower esophageal sphincters in healthy dogs. During each of three consecutive general anesthesia episodes administered to eight healthy adult research colony dogs with a standardized protocol, the EndoFLIP catheter was positioned to measure cross-sectional area, intrabag pressure, upper and lower esophageal sphincter length at two different balloon fill volumes (30 and 40 mL) and two body positions (lateral and dorsal recumbency). From these measured variables, a distensibility index was also calculated. Mixed effect analysis of variance was used to evaluate the fixed marginal and interaction effects of anesthesia episode, body position, and balloon volume on measured and calculated variables. For the upper esophageal sphincter significant interactions were present between anesthetic episode and body position for all variables except intrabag pressure; adjusting for body position significant differences were present between anesthetic episodes for all variables except distensibility index; adjusting for anesthetic episode cross-sectional area, intrabag pressure, upper esophageal sphincter length and distensibility index were all affected by body position. For the lower esophageal sphincter distensibility index was the only variable where a significant interaction between anesthesia episode and body position occurred; cross-sectional area, intrabag pressure, and lower esophageal length were not significantly affected by anesthesia episode when adjusting for body position; distensibility index was the only variable significantly affected by body position. Measurements of the geometry of the lower esophageal sphincter as measured by the EndoFLIP device were consistent under conditions of general anesthesia. Similar measurements taken at the upper esophageal sphincter displayed greater variability between anesthetic episodes and were affected to a greater extent by body position. Body position should be standardized in studies using the EndoFLIP to assess geometric and functional characteristics of the upper and lower esophageal sphincters.

Diagnosis of Swallowing Disorders: How We Interpret Pharyngeal Manometry

PURPOSE OF REVIEW

We provide an overview of the clinical application of novel pharyngeal high-resolution impedance manometry (HRIM) with pressure flow analysis (PFA) in our hands with example cases.

RECENT FINDINGS

In our Centre, we base our interpretation of HRIM recordings upon a qualitative assessment of pressure-impedance waveforms during individual swallows, as well as a quantitative assessment of averaged PFA swallow function variables. We provide a description of two global swallowing efficacy measures, the swallow risk index (SRI), reflecting global swallowing dysfunction (higher SRI = greater aspiration risk) and the post-swallow impedance ratio (PSIR) detecting significant post-swallow bolus residue. We describe a further eight swallow function variables specific to the hypopharynx and upper esophageal sphincter (UES), assessing hypo-pharyngeal distension pressure, contractility, bolus presence and flow timing, and UES basal tone, relaxation, opening and contractility. Pharyngeal HRIM has now come of age, being applicable for routine clinical practice to assess the biomechanics of oropharyngeal swallowing dysfunction. In the future, it may guide treatment strategies and allow more objective longitudinal follow-up on clinical outcomes.

The Esophagiome: concept, status, and future perspectives

The term "Esophagiome" is meant to imply a holistic, multiscale treatment of esophageal function from cellular and muscle physiology to the mechanical responses that transport and mix fluid contents. The development and application of multiscale mathematical models of esophageal function are central to the Esophagiome concept. These model elements underlie the development of a "virtual esophagus" modeling framework to characterize and analyze function and disease by quantitatively contrasting normal and pathophysiological function. Functional models incorporate anatomical details with sensory-motor properties and functional responses, especially related to biomechanical functions, such as bolus transport and gastrointestinal fluid mixing. This brief review provides insight into Esophagiome research. Future advanced models can provide predictive evaluations of the therapeutic consequences of surgical and endoscopic treatments and will aim to facilitate clinical diagnostics and treatment.

Pharyngeal Pressure and Timing During Bolus Transit

Determining intrabolus pressure (IBP) at the upper esophageal sphincter (UES) and in the esophagus has given compelling evidence that IBP can be a predictor for swallowing dysfunction. Studies have looked most superiorly at the low hypopharynx region but there has been no inquiry into what IBP measures throughout the entire pharynx can tell us. We present a study to describe the pressures within and surrounding the moving bolus throughout the pharynx and into the UES. Simultaneous high-resolution manometry (HRM) and videofluoroscopy were performed in ten healthy subjects swallowing ten 10 mL thin-liquid barium boluses. Three events surrounding bolus movement were tracked via videofluoroscopy, and two additional events were found using manometric measures. As the bolus passes through the pharynx, low pressure is created at and below the head of the bolus. A modest pressure increase is seen as the bolus passes through the pharynx, and finally, high pressure is observed at the bolus tail, followed by an even larger pressure generation of a clearance event. HRM allows for greater resolution in data collection in the pharynx and in this study, aided in identifying semi-unique characteristics around the hypopharynx and the UES which are consistent with the complex anatomy of the regions and the transition of the UES from active closure to relaxed opening. In the future, additional studies designed to look at aged and diseased populations may lead to better understanding of disease etiology, and treatment options.

Pressure topography metrics for high-resolution pharyngeal-esophageal manofluorography-a normative study of younger and older adults

BACKGROUND

We aimed to define normative values for novel pressure topography metrics for high-resolution pharyngeal-esophageal manofluorography. The effects of age, gender, and bolus properties were examined.

METHODS

Concurrent high-resolution manometry (HRM) and videofluoroscopy data were collected from 22 younger (aged 21-40) and 22 older (aged 60-80) healthy subjects. Pressure topography was analyzed by correlating pressure domains with videofluoroscopic events. Nine pressure topography metrics of the pharyngeal and proximal esophageal swallow were extracted; four of these were also compared with previously obtained esophageal HRM studies to assess the effects of catheter diameter.

KEY RESULTS

Older individuals exhibited more vigorous contractility in the pharynx than did younger subjects with all bolus types, but the greatest values for both groups were with effortful swallow and on that measure the age groups were similar. Upper esophageal sphincter (UES) intrabolus pressure during sphincter opening was also greater in the older subjects. Some gender differences were observed, particularly related to proximal esophageal contractile vigor. Bolus consistency had no consistent effect. Studies using the larger catheter diameter resulted in significantly greater contractile vigor in the UES and proximal esophagus.

CONCLUSIONS & INFERENCES

Older adults exhibited more vigorous pharyngeal contractions than young adults, albeit within a similar range of capacity, perhaps reflecting a compensatory response to other age-related physiological changes. Greater UES intrabolus pressures observed during bolus transit in the older group likely reflect reduced UES compliance with age. Normative data on novel HRM metrics collected in this study can serve as a reference for future clinical studies.

Upper esophageal sphincter mechanical states analysis: a novel methodology to describe UES relaxation and opening

The swallowing muscles that influence upper esophageal sphincter (UES) opening are centrally controlled and modulated by sensory information. Activation of neural inputs to these muscles, the intrinsic cricopharyngeus muscle and extrinsic suprahyoid muscles, results in their contraction or relaxation, which changes the diameter of the lumen, alters the intraluminal pressure and ultimately inhibits or promotes flow of content. This relationship that exists between the changes in diameter and concurrent changes in intraluminal pressure has been used previously to calculate the “mechanical states” of the muscle; that is when the muscles are passively or actively, relaxing or contracting. Diseases that alter the neural pathways to these muscles can result in weakening the muscle contractility and/or decreasing the muscle compliance, all of which can cause dysphagia. Detecting these changes in the mechanical state of the muscle is difficult and as the current interpretation of UES motility is based largely upon pressure measurement (manometry), subtle changes in the muscle function during swallow can be missed. We hypothesized that quantification of mechanical states of the UES and the pressure-diameter properties that define them, would allow objective characterization of the mechanisms that govern the timing and extent of UES opening during swallowing. To achieve this we initially analyzed swallows captured by simultaneous videofluoroscopy and UES pressure with impedance recording. From these data we demonstrated that intraluminal impedance measurements could be used to determine changes in the internal diameter of the lumen when compared to videofluoroscopy. Then using a database of pressure-impedance studies, recorded from young and aged healthy controls and patients with motor neuron disease, we calculated the UES mechanical states in relation to a standardized swallowed bolus volume, normal aging and dysphagia pathology. Our results indicated that eight different mechanical states were almost always seen during healthy swallowing and some of these calculated changes in muscle function were consistent with the known neurally dependent phasic discharge patterns of cricopharyngeus muscle activity during swallowing. Clearly defined changes in the mechanical states were observed in motor neuron disease when compared to age matched healthy controls. Our data indicate that mechanical state predictions were simple to apply and revealed patterns consistent with the known neural inputs activating the different muscles during swallowing.

Automatische Impedantie Manometrie (AIM): objectieve diagnostiek van oro-faryngale dysfagie

AUTOMATED IMPEDANCE MANOMETRY (AIM): OBJECTIVE DIAGNOSIS OF OROPHARYNGEAL DYSPHAGIA: This review article aims to demonstrate the clinical potential of Automated Impedance Manometry (AIM) as a new, non-radiological technique for screening and diagnosis of oro-pharyngeal dysphagia. An integrated - rather than separate - analysis of pressure and impedance patterns generated in the pharynx when swallowing a food bolus, can be a useful complement to the radiological investigations considered as gold standard today. Major advantages are the objective nature of this technique and the fully automated calculation of various swallow parameters. A global measure of swallowing function can be derived (a Swallow Risk Index, SRI) and is related to (the severity of) the risk of aspiration and the presence of pharyngeal post-swallow residue. It was shown that aspiration on videofluoroscopy was accurately detected by using AIM with a sensitivity of 0.88 and a specificity of 0.96. AIM analysis can be performed quickly and is reliable in the hands of different end users. Various parameters are sufficiently sensitive to detect changes in bolus consistency and - as was recently found - are influenced by swallowing manoeuvers. Furthermore, different patterns of deviant swallow parameters can be found in different patient populations. Whether this observation can provide specific diagnoses and - as a consequence - more targeted treatments is currently under investigation.

Impedance Analysis Using High-resolution Impedance Manometry Facilitates Assessment of Pharyngeal Residue in Patients With Oropharyngeal Dysphagia

Background/Aims

Impedance analysis using high-resolution impedance manometry (HRIM) enables the recognition of pharyngeal residue in patients with oropharyngeal dysphagia. The aims of this study were to evaluate appropriate criteria for impedance analysis in a large patient cohort, as well as the diagnostic accuracy and agreement of analysis performed by HRIM trainees.

Methods

We reviewed 33 controls (13 males; median age, 61.2 years) and 104 oropharyngeal dysphagia patients (61 males; median age, 70.4 years) who underwent a flexible endoscopic evaluation of swallowing study (FEES) and HRIM. Two experts compared the pharyngeal residue on FEES and impedance color pattern at 1,000, 1,500 and 2,000 Ω of the impedance bar. Three trainees were given a 60 minutes tutorial to determine the diagnostic accuracy and agreement of this analysis.

Results

The diagnostic sensitivity of experts for predicting liquid residue was 73.1% for 1,000 Ω, 96.2% for 1,500 Ω and 100% for 2,000 Ω. Significantly higher sensitivity was observed at 1,500 Ω compared to 1,000 Ω (P < 0.001). The diagnostic specificity of experts for liquid residue was 98.3% for 1,000 Ω, 96.6% for 1,500 Ω and 83.1% for 2,000 Ω. There was a higher specificity at 1,500 Ω compared to 2,000 Ω (P = 0.008). The κ value among the 3 trainees was 0.89 and the diagnostic accuracy of the trainees for liquid residue was comparable to that of the experts.

Conclusions

The impedance analysis at 1,500 Ω provides more accurate information for the detection of liquid residue, irrespective of the level of expertise.

Swallowing dysfunction in healthy older people using pharyngeal pressure-flow analysis

BACKGROUND

Age-related loss of swallowing efficiency may occur for multiple reasons. Objective assessment of individual dysfunctions is difficult and may not clearly differentiate these from normal. Pharyngeal pressure-flow analysis is a novel technique that allows quantification of swallow dysfunction predisposing to aspiration risk based on a swallow risk index (SRI). In this study, we examined the effect of ageing on swallow function.

METHODS

Studies were performed in 68 healthy subjects aged 20-91 years (mean 59 years; 29 male), asymptomatic for oropharyngeal disease. Swallowing of liquid and viscous boluses was recorded with a pressure-impedance catheter. Indices of swallow function including the SRI, postswallow residues, upper esophageal sphincter opening and bolus transit time were derived using purpose designed software.

KEY RESULTS

Swallow function worsened with increasing age with a significant decline after 80 years. Higher SRI correlated with increasing age (r = 0.257, p < 0.05 for liquids and r = 0.361, p < 0.005 viscous bolus). Subjects over 80 years were overrepresented amongst those with an SRI considered diagnostically relevant (SRI > 15). In addition, upper esophageal sphincter opening was reduced and postswallow residues increased in older subjects.

CONCLUSIONS & INFERENCES

Pharyngeal pressure-flow analysis reveals multiple functional abnormalities in older individuals. The higher SRI levels seen in asymptomatic elders possibly reflect a loss of functional reserve with ageing. Automated impedance manometry analysis of swallow function may allow the risk of developing disordered swallowing to be quantified numerically.

Utilizing intrabolus pressure and esophagogastric junction pressure to predict transit in patients with Dysphagia

Background/Aims

High-resolution manometry (HRM), with a greatly increased number of recording sites and decreased spacing between sites, allows evaluation of the dynamic simultaneous relationship between intrabolus pressure (IBP) and esophagogastric junction (EGJ) relaxation pressure. We hypothesized that bolus transit may occur when IBP overcomes integrated relaxation pressure (IRP) and analyzed the relationships between peristalsis pattern and the discrepancy between IBP and IRP in patients with dysphagia.

Methods

Twenty-two dysphagia patients with normal EGJ relaxation were examined with a 36-channel HRM assembly. Each of the 10 examinations was performed with 20 and 30 mmHg pressure topography isobaric contours, and findings were categorized based on the Chicago classification. We analyzed the relationships between peristalsis pattern and the discrepancy between IBP and IRP.

Results

Twenty-two patients were classified by the Chicago classification: 1 patient with normal EGJ relaxation and normal peristalsis, 8 patients with intermittent hypotensive peristalsis and 13 patients with frequent hypotensive peristalsis. A total of 220 individual swallows were analyzed. There were no statistically significant relationships between peristalsis pattern and the discrepancy between IBP and IRP on the 20 or 30 mmHg isobaric contours.

Conclusions

Peristalsis pattern was not associated with bolus transit in patients with dysphagia. However, further controlled studies are needed to evaluate the relationship between bolus transit and peristalsis pattern using HRM with impedance.

Upper esophageal sphincter and esophageal motility in patients with chronic cough and reflux: assessment by high-resolution manometry

The pathophysiology of chronic cough and its association with dsymotility and laryngopharyngeal reflux remains unclear. This study applied high-resolution manometry (HRM) to obtain a detailed evaluation of pharyngeal and esophageal motility in chronic cough patients with and without a positive reflux-cough symptom association probability (SAP). Retrospective analysis of 66 consecutive patients referred for investigation of chronic cough was performed. Thirty-four (52%) were eligible for inclusion (age 55 [19-77], 62% female). HRM (ManoScan 360, Given/Sierra Scientific Instruments, Mountain View, CA) with 10 water swallows was performed followed by a 24-hour ambulatory pH monitoring. Of this group, 21 (62%) patients had negative reflux-cough SAP (group A) and 13 (38%) had positive SAP (group B). Results from 23 healthy controls were available for comparison (group C). Detailed analysis revealed considerable heterogeneity. A small number of patients had pathological upper esophageal sphincter (UES) function (n=9) or esophageal dysmotility (n=1). The overall baseline UES pressure was similar, but average UES residual pressure was higher in groups A and B than in control group C (-0.2 and -0.8mmHg vs. -5.4mmHg; P<0.018 and P<0.005). The percentage of primary peristaltic contractions was lower in group B than in groups A and C (56% vs. 79% and 87%; P=0.03 and P<0.002). Additionally, intrabolus pressure at the lower esophageal sphincter was higher in group B than in group C (15.5 vs. 8.9; P=0.024). HRM revealed changes to UES and esophageal motility in patients with chronic cough that are associated with impaired bolus clearance. These changes were most marked in group B patients with a positive reflux-cough symptom association.

Evaluation of esophageal motor function in clinical practice

Esophageal motor function is highly coordinated between central and enteric nervous systems and the esophageal musculature, which consists of proximal skeletal and distal smooth muscle in three functional regions, the upper and lower esophageal sphincters, and the esophageal body. While upper endoscopy is useful in evaluating for structural disorders of the esophagus, barium esophagography, radionuclide transit studies, and esophageal intraluminal impedance evaluate esophageal transit and partially assess motor function. However, esophageal manometry is the test of choice for the evaluation of esophageal motor function. In recent years, high-resolution manometry (HRM) has streamlined the process of acquisition and display of esophageal pressure data, while uncovering hitherto unrecognized esophageal physiologic mechanisms and pathophysiologic patterns. New algorithms have been devised for analysis and reporting of esophageal pressure topography from HRM. The clinical value of HRM extends to the pediatric population, and complements preoperative evaluation prior to foregut surgery. Provocative maneuvers during HRM may add to the assessment of esophageal motor function. The addition of impedance to HRM provides bolus transit data, but impact on clinical management remains unclear. Emerging techniques such as 3-D HRM and impedance planimetry show promise in the assessment of esophageal sphincter function and esophageal biomechanics.

Upper esophageal sphincter impedance as a marker of sphincter opening diameter

The measurement of the physical extent of opening of the upper esophageal sphincter (UES) during bolus swallowing has to date relied on videofluoroscopy. Theoretically luminal impedance measured during bolus flow should be influenced by luminal diameter. In this study, we measured the UES nadir impedance (lowest value of impedance) during bolus swallowing and assessed it as a potential correlate of UES diameter that can be determined nonradiologically. In 40 patients with dysphagia, bolus swallowing of liquids, semisolids, and solids was recorded with manometry, impedance, and videofluoroscopy. During swallows, the UES opening diameter (in the lateral fluoroscopic view) was measured and compared with automated impedance manometry (AIM)-derived swallow function variables and UES nadir impedance as well as high-resolution manometry-derived UES relaxation pressure variables. Of all measured variables, UES nadir impedance was the most strongly correlated with UES opening diameter. Narrower diameter correlated with higher impedance (r = -0.478, P < 0.001). Patients with <10 mm, 10-14 mm (normal), and ≥ 15 mm UES diameter had average UES nadir impedances of 498 ± 39 Ohms, 369 ± 31 Ohms, and 293 ± 17 Ohms, respectively (ANOVA P = 0.005). A higher swallow risk index, indicative of poor pharyngeal swallow function, was associated with narrower UES diameter and higher UES nadir impedance during swallowing. In contrast, UES relaxation pressure variables were not significantly altered in relation to UES diameter. We concluded that the UES nadir impedance correlates with opening diameter of the UES during bolus flow. This variable, when combined with other pharyngeal AIM analysis variables, may allow characterization of the pathophysiology of swallowing dysfunction.

A novel method for the nonradiological assessment of ineffective swallowing

OBJECTIVES

This validation study evaluates a new manometry impedance-based approach for the objective assessment of pharyngeal function relevant to postswallow bolus residue.

METHODS

We studied 23 adult and pediatric dysphagic patients who were all referred for a videofluoroscopy, and compared these patients with 10 adult controls. The pharyngeal phase of swallowing of semisolid boluses was recorded with manometry and impedance. Fluoroscopic evidence of postswallow bolus residue was scored. Pharyngeal pressure impedance profiles were analyzed. Computational algorithms measured peak pressure (Peak P), pressure at nadir impedance (PNadImp), time from nadir impedance to PeakP (PNadImp-PeakP), the duration of impedance drop in the distal pharynx (flow interval), upper esophaghageal sphincter (UES) relaxation interval (UES-RI), nadir UES pressure (NadUESP), UES intrabolus pressure (UES-IBP), and UES resistance. A swallow risk index (SRI) was derived by the formula: SRI=(FI × PNadImp)/(PeakP × (TNadImp-PeakP+1)) × 100.

RESULTS

In all, 76 patient swallows (35 with residue) and 39 control swallows (12 with residue) were analyzed. Different functional variables were found to be altered in relation to residue. In both controls and patients, flow interval was longer in relation to residue. In controls, but not patients, residue was associated with an increased PNadImp (suggestive of increased pharyngeal IBP). Controls with residue had increased UES-IBP, NadUESP, and UES resistance compared with patients with residue. Residue in patients was related to a prolonged UES-RI. The SRI was elevated in relation to residue in both controls and patients and an average SRI of 9 was optimally predictive of residue (sensitivity 75% and specificity 80%).

CONCLUSIONS

We present novel findings in control subjects and dysphagic patients showing that combined manometry and impedance recordings can be objectively analyzed to derive pressure-flow variables that are altered in relation to the bolus residual and can be combined to predict ineffective pharyngeal swallowing.

Pharyngeal swallow adaptations to bolus volume measured with high-resolution manometry

OBJECTIVE

: To determine the effect of bolus volume on pharyngeal swallowing using high-resolution manometry (HRM).

STUDY DESIGN

: Repeated measures with subjects serving as own controls.

METHODS

: Twelve subjects swallowed four bolus volumes in the neutral head position: saliva; 5 mL water; 10 mL water; and 20 mL water. Pressure measurements were taken along the length of the pharynx using a high-resolution manometer, with emphasis placed on the velopharynx, tongue base, and upper esophageal sphincter (UES). Variables were analyzed across bolus volumes using three-way repeated measures analysis of covariance (ANCOVA) investigating the effect of sex, bolus volume, and pharynx length. Pearson's product moment tests were performed to evaluate how pharyngeal pressure and timing events changed across bolus volume.

RESULTS

: Velopharyngeal duration, maximum tongue base pressure, tongue base pressure rise rate, UES opening duration, and total swallow duration varied significantly across bolus volume. Sex did not have an effect, whereas pharynx length appeared to affect tongue base pressure duration. Maximum velopharyngeal pressure and minimum UES pressure had a direct relationship with bolus volume, whereas maximum tongue base pressure had an inverse relationship. Velopharyngeal pressure duration, UES opening duration, and total swallow duration increased as bolus volume increased.

CONCLUSIONS

: Differences in pharyngeal pressures and timing of key pressure events were detected across varying bolus volumes. Knowing the relationships between bolus volume and pharyngeal pressure activity can be valuable when diagnosing and treating dysphagic patients.

Physiological parameters for oral delivery and in vitro testing

Pharmaceutical solid oral dosage forms must undergo dissolution in the intestinal fluids of the gastrointestinal tract before they can be absorbed and reach the systemic circulation. Therefore, dissolution is a critical part of the drug-delivery process. The rate and extent of drug dissolution and absorption depend on the characteristics of the active ingredient as well as properties of the dosage form. Just as importantly, characteristics of the physiological environment such as buffer species, pH, bile salts, gastric emptying rate, intestinal motility, and hydrodynamics can significantly impact dissolution and absorption. While significant progress has been made since 1970 when the first compendial dissolution test was introduced (USP apparatus 1), current dissolution testing does not take full advantage of the extensive physiologic information that is available. For quality control purposes, where the question is one of lot-to-lot consistency in performance, using nonphysiologic test conditions that match drug and dosage form properties with practical dissolution media and apparatus may be appropriate. However, where in vitro-in vivo correlations are desired, it is logical to consider and utilize knowledge of the in vivo condition. This publication critically reviews the literature that is relevant to oral human drug delivery. Physiologically relevant information must serve as a basis for the design of dissolution test methods and systems that are more representative of the human condition. As in vitro methods advance in their physiological relevance, better in vitro-in vivo correlations will be possible. This will, in turn, lead to in vitro systems that can be utilized to more effectively design dosage forms that have improved and more consistent oral bioperformance.

The contractile deceleration point: an important physiologic landmark on oesophageal pressure topography

BACKGROUND

This study aimed to correlate oesophageal bolus transit with features of oesophageal pressure topography (OPT) plots and establish OPT metrics for accurately measuring peristaltic velocity.

METHODS

About 18 subjects underwent concurrent OPT and fluoroscopy studies. The deglutitive Contractile Front Velocity (CFV) in OPT plots was subdivided into an initial fast phase (CFV(fast)) and subsequent slow phase (CFV(slow)) separated by a user-defined deceleration point (CDP). Fluoroscopy studies were analyzed for the transition from the initial rapidly propagated luminal closure associated with peristalsis to slow bolus clearance characteristic of phrenic ampullary emptying and to identify the pressure sensors at the closure front and at the hiatus. Oesophageal pressure topography measures were correlated with fluoroscopic milestones of bolus transit. Oesophageal pressure topography studies from another 68 volunteers were utilized to develop normative ranges for CFV(fast) and CFV(slow).

KEY RESULTS

A distinct change in velocity could be determined in all 36 barium swallows with the fast and slow contractile segments having a median velocity of 4.2 cm s(-1) and 1.0 cm s(-1), respectively. The CDP noted on OPT correlated closely with formation of the phrenic ampulla making CFV(fast) (mean 5.1 cm s(-1)) correspond closely to peristaltic propagation and CFV(slow) (mean 1.7 cm s(-1)) to ampullary emptying.

CONCLUSIONS & INFERENCES

The deceleration point in the CFV on OPT plots accurately demarcated the early region in which the CFV reflects peristaltic velocity (CFV(fast)) from the later region where it reflects the progression of ampullary emptying (CFV(slow)). These distinctions should help objectify definitions of disordered peristalsis, especially spasm, and improve understanding of impaired bolus transit across the oesophagogastric junction.

New technologies in the gastrointestinal clinic and research: Impedance and high-resolution manometry

The last five years have been an exciting time in the study of esophageal motor disorders due to the recent advances in esophageal function testing. New technologies have emerged, such as intraluminal impedance, while conventional techniques, such as manometry, have enjoyed many improvements due to advances in transducer technology, computerization and graphic data presentation. While these techniques provide more detailed information regarding esophageal function, our understanding of whether they can improve our ability to diagnose and treat patients more effectively is evolving. These techniques are also excellent research tools and they have added substantially to our understanding of esophageal motor function in dysphagia. This review describes the potential benefits that these new technologies may have over conventional techniques for the evaluation of dysphagia.

Esophageal motility testing: impedance-based transit measurement and high-resolution manometry

Esophageal function tests are widely used, not only to obtain insight into esophageal physiology and pathophysiology in a research setting, but also to diagnose esophageal motor disorders in patients with symptoms such as dysphagia and chest pain. While esophageal function testing has long been considered almost synonymous with manometry, recently new techniques such as impedance measurement and high-resolution manometry have emerged. With impedance monitoring the transit of a bolus through the esophagus can be studied without the use of ionizing radiation. High-resolution manometry offers a highly detailed and comprehensive view of esophageal pressure patterns. Multichannel high resolution manometry with color plotting facilitates positioning of the catheter and interpretation of the tracings. In this article the development, clinical usefulness, and indications of these new tests are discussed.

Liquid in the gastroesophageal segment promotes reflux, but compliance does not: a mathematical modeling study

The mechanical force relationships that distinguish normal from chronic reflux at sphincter opening are poorly understood and difficult to measure in vivo. Our aim was to apply physics-based computer simulations to determine mechanical pathogenesis of gastroesophageal reflux. A mathematical model of the gastroesophageal segment (GES) was developed, incorporating the primary anatomical and physiomechanical elements that drive GES opening and reflux. In vivo data were used to quantify muscle stiffness, sphincter tone, and gastric pressure. The liquid lining the mucosa was modeled as an "effective liquid film" between the mucosa and a manometric catheter. Newton's second law was solved mathematically, and the space-time details of opening and reflux were predicted for systematic variations in gastric pressure increase, film thickness, muscle stiffness, and tone. "Reflux" was defined as "2 ml of refluxate entering the esophagus within 1 s." GES opening and reflux were different events. Both were sensitive to changes in gastric pressure and sphincter tone. Reflux initiation was extremely sensitive to the liquid film thickness; the protective function of the sphincter was destroyed with only 0.4 mm of liquid in the GES. Compliance had no effect on reflux initiation, but affected reflux volume. The presence of abnormal levels of liquid within the collapsed GES can greatly increase the probability for reflux, suggesting a mechanical mechanism that may differentiate normal reflux from gastroesophageal reflux disease. Compliance does not affect the probability for reflux, but affects reflux volume once it occurs. Opening without reflux suggests the existence of "gastroesophageal pooling" in the distal esophagus, with clinical implications.

Utilizing intraluminal pressure gradients to predict esophageal clearance: a validation study

BACKGROUND

Esophageal bolus clearance requires a preferential esophagogastric pressure gradient sustained for a sufficient period. We aimed to validate a high-resolution manometry (HRM) paradigm for predicting bolus clearance.

METHODS

Twenty volunteers and 30 patients were studied with HRM during barium swallows with concurrent fluoroscopy. Simultaneous bolus domain pressure and esophagogastric junction (EGJ) obstruction pressure were plotted and flow permissive time was tallied during which the bolus domain pressure exceeded the EGJ obstruction pressure. Distal peristaltic integrity was assessed at incrementally increasing pressure isobaric contour thresholds from 15-40 mmHg. ROC analysis was performed to assess the sensitivity and specificity of cutoff values for flow permissive time and peristaltic amplitude for predicting incomplete clearance as verified fluoroscopically.

RESULTS

Flow permissive time < or =2.5 s had a sensitivity of 86% and specificity of 92% for predicting incomplete clearance. In contrast, a 30-mmHg peristaltic amplitude had a sensitivity of only 48% and specificity of 88%. Incomplete clearance was variably attributable to functional EGJ obstruction, hiatus hernia, or impaired peristalsis.

CONCLUSIONS

A detailed analysis of intraluminal pressure gradients in the distal esophagus and across the EGJ in the postdeglutitive period predicts esophageal bolus clearance with far greater accuracy than any threshold value of peristaltic amplitude.

Physiology of the oesophageal transition zone in the presence of chronic bolus retention: studies using concurrent high resolution manometry and digital fluoroscopy

Distinct contraction waves (CWs) exist above and below the transition zone (TZ) between the striated and smooth muscle oesophagus. We hypothesize that bolus transport is impaired in patients with abnormal spatio-temporal coordination and/or contractile pressure in the TZ. Concurrent high resolution manometry and digital fluoroscopy were performed in healthy subjects and patients with reflux oesophagitis; a condition associated with ineffective oesophageal contractility and clearance. A detailed analysis of space-time variations in bolus movement, intra-bolus and intra-luminal pressure was performed on 17 normal studies and nine studies in oesophagitis patients with impaired bolus transit using an interactive computer based system. Compared with normal controls, oesophagitis patients had greater spatial separation between the upper and lower CW tails [median 5.2 cm (range 4.4-5.6) vs 3.1 cm (2.2-3.7)], the average relative pressure within the TZ region (TZ strength) was lower [30.8 mmHg (28.3-36.5) vs 45.8 mmHg (36.1-55.7), P < 0.001], and the risk of bolus retention was higher (90%vs 12%; P < 0.01). The presence of bolus retention was associated with a wider spatial separation of the upper and lower CWs (>3 cm, the upper limit of normal; P < 0.002), independent of the presence of oesophagitis. We conclude that bolus retention in the TZ is associated with excessively wide spatial separation between the upper and lower CWs and lower TZ muscle squeeze. These findings provide a physio-mechanical basis for the occurrence of bolus retention at the level of the aortic arch, and may underlie impaired clearance with reflux oesophagitis.

Diagnostic evaluation of dysphagia

Taking a careful history is vital for the evaluation of dysphagia. The history will yield the likely underlying pathophysiologic process and anatomic site of the problem in most patients, and is crucial for determining whether subsequently detected radiographic or endoscopic 'anomalies' are relevant or incidental. Although the symptoms of pharyngeal dysphagia can be multiple and varied, the typical features of neurogenic pharyngeal dysphagia are highly specific, and can accurately distinguish pharyngeal from esophageal disorders. The history will also dictate whether the next diagnostic procedure should be endoscopy, a barium swallow or esophageal manometry. In some difficult cases, all three diagnostic techniques may need to be performed to establish an accurate diagnosis. Stroke is the most common cause of pharyngeal dysphagia. A videoradiographic swallow study is vital in such cases to determine the extent and timing of aspiration and the severity and mechanics of dysfunction as a prelude to therapy.

High-resolution manometry

Recently, high-resolution oesophageal manometry was added to the armamentarium of researchers and gastroenterologists. Current studies suggest that the yield of high-resolution oesophageal manometry is higher than that of conventional pull-through manometry and is at least comparable to that of sleeve sensor manometry. Probably the most important advantage of solid-state high-resolution manometry is that it makes oesophageal manometry faster and easier to perform. Topographic plotting of high-resolution manometry signals facilitates their interpretation. It is concluded that high-resolution manometry is a promising technique for the evaluation of oesophageal motor function. Further studies will have to determine whether high-resolution manometry is superior to conventional manometry in the diagnostic work-up of patients with oesophageal symptoms.

Utilizing intraluminal pressure differences to predict esophageal bolus flow dynamics

Successful esophageal emptying depends on the generation of a sustained intrabolus pressure (IBP) sufficient to overcome esophagogastric junction (EGJ) obstruction. Our aim was to develop a manometric analysis paradigm that describes the bolus driving pressure difference and the flow permissive time for esophageal bolus transit. Twenty normal subjects were studied with a 36-channel manometry assembly (1-cm spacing) during two 5- and one 10-ml barium swallows and concurrent fluoroscopy. Bolus domain pressure plots were generated by plotting bolus domain pressure (BDP) and EGJ relaxation pressure. BDP was defined as the pressure midway between the peristaltic ramp-up and the proximal margin of the EGJ. The flow permissive time was defined as the period where the BDP was > or = EGJ relaxation pressure. The mean BDP was 11.7 +/- 1.0 mmHg (SE), and the mean flow permissive time was 3.9 +/- 0.4 s for 5-ml swallows in normal controls. The mean BDP difference during flow was 4.0 +/- 1.0 mmHg. There was no significant difference in the fluoroscopic transit time and the flow permissive time calculated from the BDP plots (5 ml: fluoroscopy 3.4 +/- 0.2 s; BDP 3.9 +/- 0.4 s, P > 0.05). BDP plots provide a reliable measurement of IBP and its relationship with EGJ relaxation. The time available for flow can be readily delineated from this analysis, and the driving pressure responsible for flow can be accurately described and quantified. This may help predict abnormal bolus transit and the underlying mechanical properties of the EGJ.

High-resolution manometry of the esophagus: more than a colorful view on esophageal motility?

Since the introduction of pressure measurement of the esophagus, there has been a stepwise improvement in manometric techniques and the recognition of esophageal manometry as a useful tool to evaluate esophageal function in clinical practice. The newest development in this field is high-resolution manometry of the esophagus. In this review, we will briefly discuss the indications for esophageal manometry and we will focus on the development of the technique of high-resolution manometry and the new insights that were obtained by using this emerging tool. We conclude that high-resolution esophageal manometry with spatiotemporal plotting of signals is a valuable research tool. Clinically, the solid-state high-resolution technique is attractive because it makes it easy to perform a high-quality manometric test. However, future studies will have to determine whether the yield of the technique is higher than that of conventional manometry.