Automated impedance-manometry analysis detects esophageal motor dysfunction in patients who have non-obstructive dysphagia with normal manometry

Four-dimensional impedance manometry volume metrics for predicting abnormal bolus retention

BACKGROUND

The objective measurement for esophageal bolus volume and bolus clearance could classify abnormal high-resolution manometry (HRM) beyond the current Chicago classification. We aimed to compare the novel four-dimensional impedance manometry (4D HRM) volume metrics with timed barium esophagram (TBE).

METHODS

Adults with esophageal symptoms undergoing HRM and TBE were included. A custom-built program for 4D HRM analysis measured esophageal luminal cross-sectional area (CSA) from impedance and subsequently derived esophageal bolus volume and clearance. 4D HRM volume metrics included pre-swallow residual volume, maximal volume, retention volume, and clearance ratio defined as 1.0-retention volume divided by the maximal volume. An abnormal TBE was defined as a column height >5 cm at 1 min or 5 min.

KEY RESULTS

A total of 95 patients (normal motility: 33%; ineffective esophageal motility: 12%; absent contractility: 10%; esophagogastric junction outflow obstruction: 30%; type I achalasia: 5%; type II achalasia: 12%) were categorized into normal TBE (58%), abnormal TBE at 1 min (17%), and abnormal TBE at 5 min (25%). The AUROC demonstrated that, among all 4D HRM volume metrics, the clearance ratio had the best performance in predicting abnormal TBE at 5 min (AUROC, 95% confidence interval: 0.89, 0.82-0.96), and exhibited a strong negative correlation with TBE at 5 min (r = -0.65; p < 0.001).

CONCLUSIONS & INFERENCES

Novel 4D HRM volume metrics provide objective measurement of esophageal bolus volume and bolus clearance. The clearance ratio has a strong correlation with TBE and could potentially serve as a substitute for TBE to measure esophageal retention.

Why so Many Patients With Dysphagia Have Normal Esophageal Function Testing

Esophageal peristalsis involves a sequential process of initial inhibition (relaxation) and excitation (contraction), both occurring from the cranial to caudal direction. The bolus induces luminal distension during initial inhibition (receptive relaxation) that facilitates smooth propulsion by contraction travelling behind the bolus. Luminal distension during peristalsis in normal subjects exhibits unique characteristics that are influenced by bolus volume, bolus viscosity, and posture, suggesting a potential interaction between distension and contraction. Examining distension-contraction plots in dysphagia patients with normal bolus clearance, ie, high-amplitude esophageal peristaltic contractions, esophagogastric junction outflow obstruction, and functional dysphagia, reveal 2 important findings. Firstly, patients with type 3 achalasia and nonobstructive dysphagia show luminal occlusion distal to the bolus during peristalsis. Secondly, patients with high-amplitude esophageal peristaltic contractions, esophagogastric junction outflow obstruction, and functional dysphagia exhibit a narrow esophageal lumen through which the bolus travels during peristalsis. These findings indicate a relative dynamic obstruction to bolus flow and reduced distensibility of the esophageal wall in patients with several primary esophageal motility disorders. We speculate that the dysphagia sensation experienced by many patients may result from a normal or supernormal contraction wave pushing the bolus against resistance. Integrating representations of distension and contraction, along with objective assessments of flow timing and distensibility, complements the current classification of esophageal motility disorders that are based on the contraction characteristics only. A deeper understanding of the distensibility of the bolus-containing esophageal segment during peristalsis holds promise for the development of innovative medical and surgical therapies to effectively address dysphagia in a substantial number of patients.

High-resolution impedance manometry for comparing bolus transit between patients with non-obstructive dysphagia and asymptomatic controls

BACKGROUND

Currently, there are no high-resolution impedance manometry (HRIM)-based diagnostic criteria for non-obstructive dysphagia (NOD). New impedance parameters, such as the esophageal impedance integral (EII) and volume of inverted impedance (VII) ratios, have shown strong correlations with bolus transit. This study compared the EII and VII ratios as diagnostic tools for NOD.

METHODS

We analyzed 36 participants (12 patients with achalasia, 12 patients with NOD [7 with normal motility and 5 with ineffective esophageal motility], and 12 asymptomatic controls) who underwent HRIM with a maximum of 5 swallows per participant. The EII and VII ratios were calculated as Z2 (post-swallow)/Z1 (pre-swallow). Bolus transit was retrospectively evaluated using transluminal impedance analysis.

KEY RESULTS

Both EII and VII ratios could effectively distinguish the achalasia group from the non-achalasia groups (area under the receiver operating characteristic curve [AUROC]: 0.83 for VII vs. 0.80 for EII; p = 0.73). However, the VII ratio was significantly better in discriminating asymptomatic controls from patients with dysphagia (NOD + achalasia) (AUROC: 0.81 vs. 0.68; p = 0.01). Moreover, the VII ratio was better in discriminating asymptomatic controls from patients with NOD (AUROC: 0.68 vs. 0.51; p = 0.06). In repeated swallows, the VII ratio was consistently the lowest in controls and the highest in patients with achalasia, whereas the EII ratio did not show a consistent pattern.

CONCLUSIONS & INFERENCES

The VII ratio was more reliable than the EII ratio for describing bolus transit and distinguishing patients with NOD from asymptomatic controls, even during repeated measures of subsequent swallows.

Normative values of intra-bolus pressure and esophageal compliance based on 4D high-resolution impedance manometry

BACKGROUND

This study aimed to quantify normative values of phase-specific intra-bolus pressure (IBP) and esophageal distensibility using 4D analysis of high-resolution-impedance manometry (HRIM).

METHODS

HRIM studies of supine swallows from 34 normal controls were analyzed with respect to the four phases of bolus transit: (1) accommodation, (2) compartmentalization, (3) peristalsis/esophageal emptying, and (4) ampullary emptying. Phase-specific IBP, bolus volume, and distensibility index (DI) in the esophageal body and esophagogastric junction (EGJ) during phases 1-3 were extracted.

RESULTS

The median (5-95th/IQR) IBP values were as follows: phase 1: 4.0 (-2.0-10.4/1.9-5.8) mmHg, phase 2: 5.7 (0.2-14.1/3.6-8.9) mmHg, and phase 3: 11.2 (2.9-19.4/7.7-15.1) mmHg. The median bolus volume calculated by integrating impedance planimetry cross-sectional areas was 4.1 ml during the compartmentalization phase. The EGJ-DI at max EGJ diameter during phase 2 and 3 was 2.8 (1.1-9.5/1.8-3.7) mm² /mmHg and 6.0 (3.2-20.3/5.1-7.8) mm² /mmHg, respectively. The phase 3 EGJ-DI values (6.0 (3.2-20.3/5.1-7.8) mm² /mmHg) were similar to those calculated using functional lumen imaging probe (FLIP) at the 60 ml volume on the same subjects (5.8 [3.5-7.2/5.0-6.4] mm² /mmHg).

CONCLUSIONS AND INFERENCES

4D-HRIM provides a standardized methodology to track the nadir impedance and provide measurements of IBP during maximal distention across phases 1-3 of bolus transit. Median IBP and delta IBP were different across the phases, supporting the need to define IBP by phase. Additionally, the EGJ-DI calculated during phase 3 was similar to the 60-ml EGJ-DI from FLIP in the same subjects suggesting that 4D-HRIM can quantify EGJ opening during primary peristalsis.

Distension contraction plots of pharyngeal/esophageal peristalsis: next frontier in the assessment of esophageal motor function

Esophageal peristalsis consists of initial inhibition (relaxation) followed by excitation (contraction), both of which move sequentially in the aboral direction. Initial inhibition results in receptive relaxation and bolus-induced luminal distension, which allows propulsion by the contraction with minimal resistance to flow. Similar to the contraction wave, luminal distension has unique waveform characteristics in normal subjects; both are modulated by bolus volume, bolus viscosity, and posture, suggesting a possible cause-and-effect relationship between the two. Distension contraction plots in patients with dysphagia with normal bolus clearance [high-amplitude esophageal contractions (HAECs), esophagogastric junction outflow obstruction (EGJOO), and functional dysphagia (FD)] reveal two major findings: 1) unlike normal subjects, there is luminal occlusion distal to bolus during peristalsis in certain patients, i.e., with type 3 achalasia and nonobstructive dysphagia; and 2) bolus travels through a narrow lumen esophagus during peristalsis in patients with HAECs, EGJOO, and FD. Aforementioned findings indicate a relative dynamic obstruction to the bolus flow during peristalsis and reduced distensibility of esophageal wall in the bolus segment of the esophagus. We speculate that a normal or supernormal contraction wave pushing bolus against resistance is the mechanism of dysphagia sensation in significant number of patients. Representations of distension and contraction, combined with objective measures of flow timing and distensibility are complementary to the current scheme of classifying esophageal motility disorders based solely on the characteristics of contraction phase of peristalsis. Better understanding of the distensibility of the bolus-containing segment of the esophagus during peristalsis will lead to the development of novel medical and surgical therapies in the treatment of dysphagia in significant number of patients.

Spastic secondary contractile patterns identified by FLIP panometry in symptomatic patients with unremarkable high-resolution manometry

BACKGROUND

Functional lumen imaging probe (FLIP) panometry can show spastic secondary contractile patterns of unclear significance in symptomatic patients who have no esophageal obstructive disorders, and no motility disorders on high-resolution manometry (HRM).

METHODS

We retrospectively analyzed non-obstructed, symptomatic patients with HRM findings of no motility disorder or ineffective esophageal motility (IEM) for whom spastic secondary contractile patterns identified by FLIP panometry were used to guide treatment. Symptoms were scored using the Brief Esophageal Dysphagia Questionnaire (BEDQ).

KEY RESULTS

We identified ten symptomatic patients treated at our medical center who met inclusion criteria (seven women; mean age 56 years; eight no motility disorder, two IEM). On FLIP panometry, seven had spastic secondary contractions at 60 ml, two at 40 ml, and one at both 40 ml and 60 ml balloon volumes. Eight patients (80%) had improvement in BEDQ scores with therapies that targeted the spastic secondary contractile patterns identified by FLIP (five botulinum toxin injection, two Esoflip dilation, and one Heller myotomy). Interestingly, review of HRM tracings revealed that all patients had a novel HRM finding of mid-vertical pressurization in at least 20% swallows, with seven exhibiting this finding in >50% of swallows.

CONCLUSIONS

This case series demonstrates that treatments targeting spastic secondary contractions identified by FLIP panometry can result in symptomatic improvement in patients with no obstructive disorder and no diagnostic motility disorder on HRM. In such patients, we have identified the novel HRM finding of mid-vertical pressurization, which might be the manometric manifestation of spasm limited to the mid-esophagus.

Dysphagia: Novel and Emerging Diagnostic Modalities

Among recent advances in diagnostics for dysphagia and esophageal motility disorders is the update to the Chicago Classification (version 4.0) for interpretation of high-resolution manometry (HRM) and diagnosis of esophageal motility disorders. The update incorporates application of complementary testing strategies during HRM, such as provocative HRM maneuvers, and recommendation for barium esophagram or functional luminal imaging probe (FLIP) panometry to help clarify inconclusive HRM findings. FLIP panometry also represents an emerging technology for evaluation of esophageal distensibility and motility at the time of endoscopy.

Distension-contraction profile of peristalsis in patients with nutcracker esophagus

INTRODUCTION

High amplitude peristaltic esophageal contractions, that is, nutcracker esophagus, were originally described in association with "angina-like pain" of esophageal origin. However, significant number of nutcracker patients also suffer from dysphagia. High-resolution esophageal manometry (HRM) assesses only the contraction phase of peristalsis. The degree of esophageal distension during peristalsis is a surrogate of relaxation and can be measured from the intraluminal esophageal impedance measurements.

AIMS

Determine the amplitude of distension and temporal relationship between distension and contraction during swallow-induced peristalsis in nutcracker patients.

METHODS

HRM impedance (HRMZ) studies were performed and analyzed in 24 nutcracker and 30 normal subjects in the Trendelenburg position. A custom-built software calculated the numerical data of the amplitudes of distension and contraction, the area under the curve (AUC) of distension and contraction, and the temporal relationship between distension and contraction.

RESULTS

In normal subjects, the distension peaks similar to contraction traverse sequentially the esophagus. The amplitude of contraction is greater in the nutcracker esophagus but the amplitude of distension and area under the curve of distension are smaller in patients compared to controls. Distension peaks are aligned closely with contraction in normal subjects, but in patients, the bolus travels faster to the distal esophagus, resulting in a smaller time interval between the onset of swallow and distension peak. Receiver operative characteristics (ROC) curve reveals high sensitivity and specificity of the above parameters in patients.

CONCLUSION

Abnormalities in the distension phase of peristalsis are a possible mechanism of dysphagia in patients with nutcracker esophagus.

European Society for Neurogastroenterology and Motility (ESNM) recommendations for the use of high-resolution manometry of the esophagus

BACKGROUND

Several patients in gastroenterology practice present with esophageal symptoms, and in case of normal endoscopy with biopsies, high-resolution manometry (HRM) is often the next step. Our aim was to develop a European consensus on the clinical application of esophageal HRM, to offer the clinician guidance in selecting patients for HRM and using its results to optimize clinical outcome.

METHODS

A Delphi consensus was initiated with 38 multidisciplinary experts from 16 European countries who conducted a literature summary and voting process on 71 statements. Quality of evidence was evaluated using grading of recommendations assessment, development, and evaluation (GRADE) criteria. Consensus (defined as >80% agreement) was reached for 33 statements.

RESULTS

The process generated guidance on when to consider esophageal HRM, how to perform it, and how to generate the report. The Delphi process also identified several areas of uncertainty, such as the choice of catheters, the duration of fasting and the position in which HRM is performed, but recommended to perform at least 10 5-ml swallows in supine position for each study. Postprandial combined HRM impedance is considered useful for diagnosing rumination. There is a large lack of consensus on treatment implications of HRM findings, which is probably the single area requiring future targeted research.

CONCLUSIONS AND INFERENCES

A multinational and multidisciplinary group of European experts summarized the current state of consensus on technical aspects, indications, performance, analysis, diagnosis, and therapeutic implications of esophageal HRM.

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.

Relationship between distension-contraction waveforms during esophageal peristalsis: effect of bolus volume, viscosity, and posture

High-resolution esophageal manometry (HRM) in its current form assesses only the contraction phase of peristalsis. Degree of esophageal distension ahead of contraction is a surrogate of relaxation and can be measured from intraluminal esophageal impedance measurements. The characteristics of esophageal contractions, i.e., their amplitude, duration, velocity, and modulating factors, have been well studied. We studied the effect of bolus volume and viscosity and posture on swallow-induced distension and contraction and the temporal relationship between the two. HRM impedance recordings of 50 healthy subjects with no esophageal symptoms were analyzed. Eight to ten swallows of 5 and 10 mL of 0.5 N saline and a viscous bolus were recorded in the supine and Trendelenburg positions. Custom-built computer software generated the distension-contraction plots and numerical data of the amplitudes of distension (cross-sectional area) and contraction, and the temporal relationship between distension and peak contraction. The hallmarks of distension waveforms are that 1) distension peak, similarly to contraction, travels the esophagus in a peristaltic fashion, and the amplitude of distension increases from the proximal-to-distal direction; 2) the amplitude of distension is greater with 10 mL than with 5 mL and greater in Trendelenburg than in supine posture; and 3) bolus viscosity increases the amplitude of distension and alters the temporal relationship between distension and contraction waveforms. We describe the characteristics of esophageal distension during peristalsis and the relationship between distension and contraction in a relatively large cohort of normal subjects. These data can be used to compare differences between normal subjects and patients with various esophageal motility disorders in future studies.NEW & NOTEWORTHY We studied esophageal distension (surrogate of inhibition) ahead of contraction during peristalsis from intraluminal esophageal impedance measurements. Esophageal distension, similarly to contraction, travels the esophagus in a sequential manner, and the amplitude of esophageal distension increases from proximal to distal direction in the esophagus. Bolus volume, viscosity and posture have significant effects on the amplitude of distension and its temporal relationship with contraction.

Characterization of Esophageal Motility in Children With Operated Esophageal Atresia Using High-resolution Impedance Manometry and Pressure Flow Analysis

OBJECTIVES

Esophageal dysmotility is common in patients with esophageal atresia (EA). High-resolution impedance manometry and pressure flow analysis (PFA) allow characterization of biomechanical events that drive bolus flow. The aims were to assess esophageal motility in children with EA, using PFA, and to test whether there is a correlation between PFA parameters and symptoms or endoscopic/histologic findings.

METHODS

High-resolution impedance manometry was performed in 16 children with EA (median age 11 years), compared with 13 patient controls (median age 14 years; P = NS vs patients). Wet swallows were analyzed using PFA. Medical charts were reviewed for symptoms and pathology results of the attendant esophagoscopy. Patients with EA were arbitrarily subgrouped according to their motility pattern: group A with presence of distal contraction in ≥50% of the swallows and group B with presence of distal contractions in <50% of the swallows.

RESULTS

Esophageal peristaltic motor patterns were abnormal in all patients with EA. Bolus transport was impaired as shown by the higher impedance ratio in EA than in controls (0.47 vs 0.22; P < 0.001). Impedance ratio was also higher in group B (n = 8) versus group A (n = 8) (P < 0.001). Symptoms of dysphagia were not correlated with the PFA measures. Contractile segment impedance, a marker of mucosal integrity, was significantly lower in the EA group.

CONCLUSIONS

Bolus transport was severely altered in patients with EA but was not predictive of symptoms. The presence of residual distal contractions is associated with a more efficient bolus propulsion.

Enhancing High-Resolution Esophageal Manometry: Use of Ancillary Techniques and Maneuvers

High-resolution manometry evaluates esophageal motor function using 10 supine water swallows. Superimposing impedance over high-resolution manometry pressure topography assesses the relationship between contraction and bolus propulsion and identifies inadequate clearance. Ancillary techniques and maneuvers augment the standard supine high-resolution manometry evaluation by challenging peristaltic function. Increasing bolus volume (rapid drink challenge) and altering bolus consistency (standardized test meal, solid swallows) enhance identification of esophageal outflow obstruction syndromes. Physiologic maneuvers (multiple rapid swallows, abdominal compression) address the ability of the esophageal smooth muscle to augment contraction vigor. Pharmacologic challenge is less commonly used clinically, and elucidates pathophysiology of esophageal motor disorders.

Pressure-impedance analysis: Assist the diagnosis and classification of ineffective esophageal motility disorder

BACKGROUND AND AIM

We elucidated the clinical significance of distal contractile integral-to-esophageal impedance integral (EII) ratio (DCIIR) in ineffective esophageal motility (IEM) adult patients.

METHODS

We recruited 101 patients with IEM (48.38 ± 1.58 years) and 42 matched healthy volunteers (44.28 ± 1.85 years) in this case-control study. All subjects underwent esophageal high-resolution impedance manometry from October 2014 to May 2018. The diagnosis of IEM was based on the Chicago Classification version 3.0. The EII, EII ratio, and DCIIR were analyzed by matlab software.

RESULTS

The EII, EII ratio, and DCIIR calculated at an impedance threshold of 1500 Ω (EII1500, EII ratio1500, and DCIIR1500, respectively) were significantly lower in the IEM group than in healthy controls (P < 0.0001, < 0.0001, and < 0.0001, respectively). Receiver operating characteristic analysis showed that DCIIR1500 < 0.008 mmHg/Ω, EII1500 > 71 000 Ω.s.cm, and EII ratio1500 > 0.43 were all predictive of IEM. Only DCIIR1500 < 0.008 mmHg/Ω remained significant in diagnosing IEM in the multivariate logistic regression analysis (odds ratio = 72.13, P < 0.001). The DCIIR1500 is negatively correlated with Eckardt score and the Reflux Disease Questionnaire (correlation coefficient = -0.2844 and -0.3136; P = 0.0006 and 0.0002, respectively). Receiver operating characteristic analysis further showed that a DCIIR1500 cut-off of 0.002 mmHg/Ω achieved the best differentiation between the IEM-alternans and IEM-persistens subtypes among IEM patients (P < 0.001).

CONCLUSIONS

The novel pressure-impedance parameter of high-resolution impedance manometry, DCIIR1500, may assist in the diagnosis and classification of IEM and correlated with clinical symptoms.

Impedance in the evaluation of the esophagus

The aim of this paper is to review esophageal electrical impedance technologies and to discuss the use of these technologies for physiological measurements, diagnostics, and therapy of esophageal disease. In order to develop a better understanding of the pathophysiology of and improve the diagnosis of esophageal disorders, such as gastroesophageal reflux disease (GERD) and achalasia, several new diagnostic tests, including intraluminal impedance, esophageal mucosal impedance, and the functional luminal imaging probe, have been developed. These technologies have proven valuable for assessment of the esophagus in recent years. They provide information on esophageal flow properties, mucosal integrity, lumen shape, and distensibility in esophageal disorders, in particular for GERD and achalasia. Despite their promise and novel clinical studies, the potential of these technologies has been far from realized. New multidisciplinary approaches will contribute to our understanding and interpretation of esophageal impedance data and disease mechanisms.

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.

British Society of Gastroenterology guidelines for oesophageal manometry and oesophageal reflux monitoring

These guidelines on oesophageal manometry and gastro-oesophageal reflux monitoring supersede those produced in 2006. Since 2006 there have been significant technological advances, in particular, the development of high resolution manometry (HRM) and oesophageal impedance monitoring. The guidelines were developed by a guideline development group of patients and representatives of all the relevant professional groups using the Appraisal of Guidelines for Research and Evaluation (AGREE II) tool. A systematic literature search was performed and the GRADE (Grading of Recommendations Assessment, Development and Evaluation) tool was used to evaluate the quality of evidence and decide on the strength of the recommendations made. Key strong recommendations are made regarding the benefit of: (i) HRM over standard manometry in the investigation of dysphagia and, in particular, in characterising achalasia, (ii) adjunctive testing with larger volumes of water or solids during HRM, (iii) oesophageal manometry prior to antireflux surgery, (iv) pH/impedance monitoring in patients with reflux symptoms not responding to high dose proton pump inhibitors and (v) pH monitoring in all patients with reflux symptoms responsive to proton pump inhibitors in whom surgery is planned, but combined pH/impedance monitoring in those not responsive to proton pump inhibitors in whom surgery is planned. This work has been endorsed by the Clinical Services and Standards Committee of the British Society of Gastroenterology (BSG) under the auspices of the oesophageal section of the BSG.

Topographical plots of esophageal distension and contraction: effects of posture on esophageal peristalsis and bolus transport

Each swallow induces a wave of inhibition followed by contraction in the esophagus. Unlike contraction, which can easily be measured in humans using high-resolution manometry (HRM), inhibition is difficult to measure. Luminal distension is a surrogate of the esophageal inhibition. The aim of this study was to determine the effect of posture on the temporal and quantitative relationship between distension and contraction along the entire length of the esophagus in normal healthy subjects by using concurrent HRM, HRM impedance (HRMZ), and intraluminal ultrasound (US). Studies were conducted in 15 normal healthy subjects in the supine and Trendelenburg positions. Both manual and automated methods were used to extract quantitative pressure and impedance-derived features from the HRMZ recordings. Topographical plots of distension and contraction were visualized along the entire length of the esophagus. Distension was also measured from the US images during 10-ml swallows at 5 cm above the lower esophageal sphincter. Each swallow was associated with luminal distension followed by contraction, both of which traversed the esophagus in a sequential/peristaltic fashion. Luminal distension (US) and esophageal contraction amplitude were greater in the Trendelenburg compared with the supine position. Length of esophageal breaks (in the transition zone) were reduced in the Trendelenburg position. Change in posture altered the temporal relationship between distension and contraction, and bolus traveled closer to the esophageal contraction in the Trendelenburg position. Topographical contraction-distension plots derived from HRMZ recordings is a novel way to visualize esophageal peristalsis. Future studies should investigate if abnormalities of esophageal distension are the cause of functional dysphagia. NEW & NOTEWORTHY Ascending contraction and descending inhibition are two important components of peristalsis. High-resolution manometry only measures the contraction phase of peristalsis. We measured esophageal distension from intraluminal impedance recordings and developed novel contraction-distension topographical plots to prove that similar to contraction, distension also travels in a peristaltic fashion. Change in posture from the supine to the Trendelenburg position also increased the amplitude of esophageal distension and contraction and altered the temporal relationship between distension and contraction.

High-resolution impedance manometry parameters in the evaluation of esophageal function of non-obstructive dysphagia patients

BACKGROUND

High-resolution impedance manometry (HRIM) allows evaluation of esophageal bolus retention, flow, and pressurization. We explored novel HRIM measures and assessed their temporal relationship to dysphagia symptoms for boluses of different volume and consistency in non-obstructive dysphagia (NOD) patients.

METHODS

Thirty-three NOD patients (n = 19 minor or no disorder of peristalsis ("Normal") and n = 14 esophagogastric junction outflow obstruction ("EGJOO")) were evaluated with HRIM. Patients were administered 5 and 10 mL liquid, semisolid, and 2 and 4 cm solid boluses and indicated bolus perception during individual swallows using a 5-point Likert scale. HRIM was analyzed to assess Chicago Classification and pressure flow metrics, esophageal impedance integral (EII) ratio, and bolus flow time (BFT).

KEY RESULTS

Overall, bolus perception increased with increasing bolus consistency (P < 0.001), but did not differ significantly between EGJOO and Normal patients. EGJOO patients had higher IRP4, higher levels of bolus residual (ie, EII ratio and IR), and restricted esophageal emptying. The results for linking semisolid bolus perception to semisolid-derived measures revealed more biomechanically plausible and consistent patterns when compared to those derived for liquid boluses. In Normal patients, perception of boluses of heavier viscosity was related to higher bolus flow resistance during transport, whilst in EGJOO, perception was related to restriction of esophageal emptying.

CONCLUSION & INFERENCES

These novel pressure-impedance measures may aid in the evaluation of NOD patients by revealing abnormal motor patterns, which may explain symptom generation. Future studies are needed to evaluate which of these measures are worthy of calculation and to establish protocol settings that allow for their meaningful interpretation.

Distal contractile to impedance integral ratio assist the diagnosis of pediatric ineffective esophageal motility disorder

OBJECTIVES

We investigated the diagnostic utility of distal contractile integral (DCI) to esophageal impedance integral (EII) ratio (DCIIR) in high-resolution impedance manometry (HRIM) of ineffective esophageal motility (IEM) in children.

METHODS

We performed HRIM in 31 children with dysphagia, odynophagia, chronic vomiting, chest pain, or heartburn sensation. Based on the Chicago classification version 3.0, 20 subjects were diagnosed with IEM, and 11 subjects were normal. We analyzed the EII and DCIIR using MATLAB software.

RESULTS

The DCIIR calculated at the impedance cutoff at 1500 Ω (DCIIR1500) were significantly lower in IEM group than patients with normal motility (P = 0.007). Receiver operating characteristic (ROC) curve analysis showed that a DCIIR1500 < 0.009 mmHg/Ω best predicted IEM in children (P < 0.001). A DCIIR1500 < 0.008 mmHg/Ω is associated with significant body weight loss > 10% within 6 months in children. (P < 0.001).

CONCLUSIONS

The calculation of DCIIR1500 may assist the automatic analysis of bolus transit in HRIM study to diagnose IEM in children. An DCIIR1500 < 0.009 mmHg/Ω may assist in the diagnosis of IEM in children, and DCIIR1500 < 0.008 mmHg/Ω correlated with significant body weight loss. The calculation of DCIIR may serve as possible parameters for HRIM.

Intrabolus Pressure Has Better Correlation Than Eosinophilia with Dysphagia Severity in Fibrostenotic Eosinophilic Esophagitis: A Pilot Study

Eosinophilic esophagitis is characterized by dysphagia with esophageal eosinophilia. We sought to determine if intrabolus pressure measurements on high-resolution manometry had any correlation with dysphagia improvement following standard therapy for patients with fibrostenotic eosinophilic esophagitis. Consecutive patients were prospectively enrolled at our swallowing center. Dysphagia scores, esophageal eosinophil counts, endoscopic reference scores, and intrabolus pressure measurements were compared at baseline and following therapy with 8 weeks of a proton-pump inhibitor and serial bougie dilation to a luminal diameter of 17 mm. Five patients were included in the study. The median age was 38 years. The average endoscopic reference score improved from 5.0 to 2.4 (p = 0.007). The mean esophageal diameter improved from 10.8 mm to 17.2 mm (p = 0.001). Dysphagia severity scores improved from a mean value of 34.2 to 10.8 (p = 0.004). Mucosal eosinophilia had no correlation with dysphagia severity. Mean intrabolus pressure improved from 21.8 mmHg to 11 mmHg (p = 0.001). There was strong correlation between a decrease in intrabolus pressure and improvement in dysphagia severity; however, this was not significant (p = 0.108). Intrabolus pressure has strong correlation with dysphagia severity following therapy for fibrostenotic eosinophilic esophagitis. Bougie dilation provides improvement in dysphagia despite persistent mucosal eosinophilia.

Genesis of Esophageal Pressurization and Bolus Flow Patterns in Patients With Achalasia Esophagus

BACKGROUND & AIMS

In patients with achalasia esophagus, swallows induce simultaneous pressure waves known as esophageal pressurization. We studied the mechanism of esophageal pressurization and bolus flow patterns in patients with type 2 or type 3 achalasia.

METHODS

We recorded high-resolution manometry with impedance and intraluminal ultrasound images concurrently in patients with type 2 achalasia (n = 6) or type 3 achalasia (n = 8) and in 10 healthy subjects (controls) during swallows of 5 mL of 0.5N saline. For each swallow, the ultrasound image was aligned with the pressure and impedance tracings to determine cavity and contact pressure, bolus arrival, bolus dwell time, and changes in muscle thickness at 5 cm and 10 cm above the lower esophageal sphincter.

RESULTS

In patients with type 2 achalasia, esophageal pressurization was associated with an increase in the muscle thickness and luminal narrowing but not complete luminal closure (ie, cavity pressure). Bolus arrival time in the distal esophagus after the onset of a swallow was delayed in patients with type 3 achalasia compared with control individuals because of early luminal closure. The early luminal closure was associated with a decrease in the muscle thickness. The bolus dwell time was shorter in patients with type 3 achalasia compared with control individuals. In patients with type 3 achalasia, the onset of simultaneous pressure wave was always a cavity pressure, but during contraction there were different periods of cavity and contact pressures in association with increases in muscle thickness that resulted in bolus segmentation.

CONCLUSIONS

We observed distinct mechanisms of esophageal pressurization and bolus flow patterns in patients with type 2 or type 3 achalasia esophagus compared with control individuals. These findings will increase our understanding of the mechanisms of dysphagia.

Impedance spectroscopy measurements as a tool for distinguishing different luminal content during bolus transit studies

BACKGROUND

Intraluminal electrical impedance is a well-known diagnostic tool used to study bolus movement in the human esophagus. However, it is use in the human colon it is hindered by the fact that the content cannot be controlled and may include liquid, gas, solid, or a mixture of these at any one time. This article investigates the use of complex impedance spectroscopy to study different luminal content (liquid and gas).

METHODS

An excised section of guinea pig proximal colon was placed in an organ bath with Krebs solution at 37°C and a custom built bioimpedance catheter was placed in the lumen. Liquid (Krebs) and gas (air) content was pumped through the lumen and the intraluminal impedance was measured at five different frequencies (1, 5.6, 31.6, 177.18 kHz and 1 MHz) at 10 samples per second. A numerical model was created to model the passage of bolus with different content and compared to the experimental data.

KEY RESULTS

Differences in mean impedance magnitude and phase angle were found (from 1 to 177.18 kHz) for different contents. The numerical results qualitatively agreed with those in the experimental study. Conductivities of bolus had an effect on detecting its passage.

CONCLUSIONS & INFERENCES

Complex impedance spectroscopy can distinguish between different luminal content within a range of measuring frequencies. The numerical model showed the importance of bolus conductivities for bolus transit studies in those where the bolus is controlled.

Inter-rater agreement of novel high-resolution impedance manometry metrics: Bolus flow time and esophageal impedance integral ratio

BACKGROUND

Novel high-resolution impedance manometry (HRIM) metrics of bolus flow time (BFT) and esophageal impedance integral (EII) ratio have demonstrated clinical utility, though the reliability of their analysis has not been assessed. We aimed to evaluate the inter-rater agreement of the BFT and EII ratio.

METHODS

HRIM studies including five upright, liquid swallows from 40 adult patients were analyzed by two raters using a customized MATLAB program to generate the BFT and EII ratio. Inter-rater agreement was assessed using the intraclass correlation coefficient (ICC) for median values generated per patient and also for all 200 swallows.

KEY RESULTS

The ICC (95% confidence interval, CI) for BFT was 0.873 (0.759-0.933) for median values and 0.838 (0.778-0.881) for all swallows. The ICC (95% CI) for EII ratio was 0.983 (0.968-0.991) for median values and 0.905 (0.875-0.928) for all swallows. Median values for both BFT and EII ratio were similar between the two raters (P-values .05).

CONCLUSIONS AND INFERENCES

The BFT and EII ratio can be reliably calculated as supported by generally excellent inter-rater agreement. Thus, broader utilization of these measures appears feasible and would facilitate further evaluation of their clinical utility.

How to Care for Patients with EA-TEF: The Known and the Unknown

PURPOSE OF REVIEW

Guidelines were recently published highlighting why esophageal atresia (EA) patients are prone to complication risks, and the need for long-term follow-up. In this review, we will focus on how to investigate and treat potential complications, as well as the pros and cons of different investigative and treatment modalities, and what areas continue to need further research.

RECENT FINDINGS

EA patients are at high risk for gastroesophageal reflux and esophageal strictures, and the sequela that result. Extraintestinal manifestations of gastroesophageal reflux disease (GERD) can appear similar to other pathologic diagnoses commonly found in EA patients, such as congenital stricture, eosinophilic esophagitis, esophageal dysmotility, tracheomalacia, recurrent fistula, aspiration, etc. Therefore, it is important to have a standardized way to monitor for these issues. pH impedance allows for detection of nonacid reflux and the height of reflux, which are important in correlating symptoms with reflux episodes. A multidisciplinary approach is beneficial in evaluating and monitoring EA patients in the long term.

Elevated intrabolus pressure identifies obstructive processes when integrated relaxation pressure is normal on esophageal high-resolution manometry

Elevated integrated relaxation pressure (IRP) on esophageal high-resolution manometry (HRM) identifies obstructive processes at the esophagogastric junction (EGJ). Our aim was to determine whether intrabolus pressure (IBP) can identify structural EGJ processes when IRP is normal. In this observational cohort study, adult patients with dysphagia and undergoing HRM were evaluated for endoscopic evidence of structural EGJ processes (strictures, rings, hiatus hernia) in the setting of normal IRP. HRM metrics [IRP, distal contractile integral (DCI), distal latency (DL), IBP, and EGJ contractile integral (EGJ-CI)] were compared among 74 patients with structural EGJ findings (62.8 ± 1.6 yr, 67.6% women), 27 patients with normal EGD (52.9 ± 3.2 yr, 70.3% women), and 21 healthy controls (27.6 ± 0.6 yr, 52.4% women). Findings were validated in 85 consecutive symptomatic patients to address clinical utility. In the primary cohort, mean IBP (18.4 ± 0.9 mmHg) was higher with structural EGJ findings compared with dysphagia with normal EGD (13.5 ± 1.1 mmHg, P = 0.002) and healthy controls (10.9 ± 0.9 mmHg, P < 0.001). However, mean IRP, DCI, DL, and EGJ-CI were similar across groups (P > 0.05 for each comparison). During multiple rapid swallows, IBP remained higher in the structural findings group compared with controls (P = 0.02). Similar analysis of the prospective validation cohort confirmed IBP elevation in structural EGJ processes, but correlation with dysphagia could not be demonstrated. We conclude that elevated IBP predicts the presence of structural EGJ processes even when IRP is normal, but correlation with dysphagia is suboptimal.NEW & NOTEWORTHY Integrated relaxation pressure (IRP) above the upper limit of normal defines esophageal outflow obstruction using high-resolution manometry. In patients with normal IRP, elevated intrabolus pressure (IBP) can be a surrogate marker for a structural restrictive or obstructive process at the esophagogastric junction (EGJ). This has the potential to augment the clinical value of esophageal HRM by raising suspicion for a structural EGJ process when IBP is elevated.

High-resolution impedance manometry parameters enhance the esophageal motility evaluation in non-obstructive dysphagia patients without a major Chicago Classification motility disorder

BACKGROUND

High-resolution impedance manometry (HRIM) allows evaluation of esophageal bolus retention, flow, and pressurization. We aimed to perform a collaborative analysis of HRIM metrics to evaluate patients with non-obstructive dysphagia.

METHODS

Fourteen asymptomatic controls (58% female; ages 20-50) and 41 patients (63% female; ages 24-82), 18 evaluated for dysphagia and 23 for reflux (non-dysphagia patients), with esophageal motility diagnoses of normal motility or ineffective esophageal motility, were evaluated with HRIM and a global dysphagia symptom score (Brief Esophageal Dysphagia Questionnaire). HRIM was analyzed to assess Chicago Classification metrics, automated pressure-flow metrics, the esophageal impedance integral (EII) ratio, and the bolus flow time (BFT).

KEY RESULTS

Significant symptom-metric correlations were detected only with basal EGJ pressure, EII ratio, and BFT. The EII ratio, BFT, and impedance ratio differed between controls and dysphagia patients, while the EII ratio in the upright position was the only measure that differentiated dysphagia from non-dysphagia patients.

CONCLUSIONS & INFERENCES

The EII ratio and BFT appear to offer an improved diagnostic evaluation in patients with non-obstructive dysphagia without a major esophageal motility disorder. Bolus retention as measured with the EII ratio appears to carry the strongest association with dysphagia, and thus may aid in the characterization of symptomatic patients with otherwise normal manometry.

How to Optimally Apply Impedance in the Evaluation of Esophageal Dysmotility

The utilization of impedance technology has enhanced our understanding and assessment of esophageal dysmotility. Esophageal high-resolution manometry (HRM) catheters incorporated with multiple impedance electrodes help assess esophageal bolus transit, and the combination is termed high-resolution impedance manometry (HRIM). Novel metrics have been developed with HRIM-including esophageal impedance integral ratio, bolus flow time, nadir impedance pressure, and impedance bolus height-that augments the assessment of esophageal bolus transit. Automated impedance-manometry (AIM) analysis has enhanced understanding of the relationship between bolus transit and pressure phenomena. Impedance-based metrics have improved understanding of the dynamics of esophageal bolus transit into four distinct phases, may correlate with symptomatic burden, and can assess the adequacy of therapy for achalasia. An extension of the use of impedance involves impedance planimetry and the functional lumen imaging probe (FLIP), which assesses esophageal biophysical properties and distensibility, and could detect patterns of esophageal contractility not seen on HRM. Impedance technology, therefore, has a significant impact on esophageal function testing in the present day.

The Potential Benefits of Applying Recent Advances in Esophageal Motility Testing in Patients with Esophageal Atresia

Infants and children with esophageal atresia commonly present with swallowing dysfunction or dysphagia. Dysphagia can lead to a range of significant consequences such as aspiration pneumonia, malnutrition, dehydration, and food impaction. To improve oral intake, the clinical diagnosis of dysphagia in patients with esophageal atresia should focus on both the pharynx and the esophagus. To characterize the complex interactions of bolus flow and motor function between mouth, pharynx, and esophagus, a detailed understanding of normal and abnormal deglutition is required through the use of adequate and objective assessment techniques. As clinical symptoms do not correlate well with conventional assessment methods of motor function such as radiology or manometry but do correlate with bolus flow, the current state-of-the-art diagnosis involves high-resolution manometry combined with impedance measurements to characterize the interplay between esophageal motor function and bolus clearance. Using a novel pressure flow analysis (PFA) method as an integrated analysis method of manometric and impedance measurements, differentiation of patients with impaired esophago-gastric junction relaxation from patients with bolus outflow disorders is clinically relevant. In this, pressure flow matrix categorizing the quantitative PFA measures may be used to make rational therapeutic decisions in patients with esophageal atresia. Through more advanced diagnostics, improved understanding of pathophysiology may improve our patient care by directly targeting the failed biomechanics of both the pharynx and the esophagus.

Impaired bolus clearance in asymptomatic older adults during high-resolution impedance manometry

BACKGROUND

Dysphagia becomes more common in old age. We performed high-resolution impedance manometry (HRIM) in asymptomatic healthy adults (including an older cohort >80 years) to assess HRIM findings in relation to bolus clearance.

METHODS

Esophageal HRIM was performed in a sitting posture in 45 healthy volunteers (n = 30 young control, mean age 37 ± 11 years and n = 15 older subjects aged 85 ± 4 years) using a 3.2-mm solid-state catheter (Solar GI system; MMS, Enschede, The Netherlands) with 25 pressure (1-cm spacing) and 12 impedance segments (2-cm intervals). Five swallows each of 5- and 10-mL liquid and viscous bolus were performed and analyzed using esophageal pressure topography metrics and Chicago classification criteria as well as pressure-flow parameters. Bolus transit was determined using standard impedance criteria. A p-value <0.05 was considered significant.

KEY RESULTS

Impaired bolus clearance occurred more frequently in asymptomatic older subjects compared with young controls (YC) during liquid (40 vs 18%, χ²  = 4.935; p < 0.05) and viscous (60 vs 17%; χ²  = 39.08; p < 0.001) swallowing. Longer peristaltic breaks (p < 0.05) and more rapid peristalsis (L: p < 0.004, V: p = 0.003) occurred in the older cohort, with reduced impedance-based clearance for both bolus consistencies (L: p < 0.05, V: p < 0.001). Decreased peristaltic vigor (distal contractile integral <450 mmHg/s/cm) was associated with reduced liquid clearance in both age groups (p < 0.001) and of viscous swallows in the older group (p < 0.001). Impedance ratio, a marker of bolus retention, was increased in older subjects during liquid (p = 0.002) and viscous (p < 0.001) swallowing.

CONCLUSIONS & INFERENCES

Impaired liquid and viscous bolus clearance, esophageal pressure topography, and pressure-flow changes were seen in asymptomatic older subjects.

Esophageal Impedance Monitoring: Clinical Pearls and Pitfalls

The development of intraluminal esophageal impedance monitoring has improved our ability to detect and measure gastroesophageal reflux without dependence on acid content. This ability to detect previously unrecognized weak or nonacid reflux episodes has had important clinical implications in the diagnosis and management of gastroesophageal reflux disease (GERD). In addition, with the ability to assess bolus transit within the esophageal lumen, impedance monitoring has enhanced the recognition and characterization of esophageal motility disorders in patients with nonobstructive dysphagia. The assessment of the intraluminal movement of gas and liquid has also been proven to be of diagnostic value in conditions such as rumination syndrome and excessive belching. Further, alternative applications of impedance monitoring, such as the measurement of mucosal impedance, have provided novel insights into assessing esophageal mucosal integrity changes as a consequence of inflammatory change. Future applications for esophageal impedance monitoring also hold promise in esophageal conditions other than GERD. However, despite all of the clinical benefits afforded by esophageal impedance monitoring, important clinical and technical shortcomings limit its diagnostic value and must be considered when interpreting study results. Overinterpretation of studies or application of impedance monitoring in patients can have deleterious clinical implications. This review will highlight the clinical benefits and limitations of esophageal impedance monitoring and provide clinical pearls and pitfalls associated with this technology.

Emerging strategies for the treatment of gastroparesis

Gastroparesis is a syndrome of delayed gastric emptying in the absence of mechanical obstruction. Symptoms can be debilitating, affect nutritional states, and significantly impact patients' quality of life. The management of these patients can prove quite difficult to many providers. This article will review the current management recommendations of gastroparesis, discuss investigational medications and interventions, and summarize future directions of therapies targeting the underlying disease process. Current therapies are subdivided into those improving gastric motility and those directly targeting symptoms. Non-pharmacologic interventions, including gastric stimulator implantation and intra-pyloric botulinum toxic injection are reviewed. A discussion of expert opinion in the field, a look into the future of gastroparesis management, and a key point summary conclude the article.

Effects of Diabetes on Salivary Gland Protein Expression of Tetrahydrobiopterin and Nitric Oxide Synthesis and Function

BACKGROUND

Xerostomia is defined as dry mouth resulting from a change in the amount or composition of saliva and is often a major oral health complication associated with diabetes mellitus (DM). Studies have shown that xerostomia is more common in females at the onset of DM. Evidence suggests that nitric oxide (NO) plays a critical role in healthy salivary gland function. However, the specific mechanisms by which NO regulates salivary gland function at the onset of DM have yet to be determined. This study has two aims: 1) to determine whether protein expression or dimerization of NO synthase enzymes (neuronal [nNOS] and endothelial [eNOS]) are altered in the onset of diabetic xerostomia; and 2) to determine whether the changes in nNOS/eNOS protein expression or dimerization are correlated with changes in NO cofactor tetrahydrobiopterin (BH4) biosynthetic enzymes (guanosine triphosphate cyclohydrolase-1 and dihydrofolate reductase).

METHODS

Functional and Western blot studies were performed in streptozotocin-induced and control Sprague-Dawley female rats with DM (type 1 [t1DM]) using standardized protocols. Confirmation of xerostomia was determined by increased water intake and decreased salivary flow rate.

RESULTS

The results showed that in female rats with DM, salivary hypofunction is correlated with decreased submandibular and parotid gland sizes. The results also show a decrease in NOS and BH4 biosynthetic enzyme in submandibular glands.

CONCLUSIONS

These results indicate that a decrease in submandibular NO-BH4 protein expression may provide insight pertaining to mechanisms for the development of hyposalivation in DM-induced xerostomia. Furthermore, understanding the role of the NO-BH4 pathway may give insight into possible treatment options for the patient with DM experiencing xerostomia.

Characterization of Esophageal Physiology Using Mechanical State Analysis

The esophagus functions to transport swallowed fluids and food from the pharynx to the stomach. The esophageal muscles governing bolus transport comprise circular striated muscle of the proximal esophagus and circular smooth muscle of the distal esophagus. Longitudinal smooth muscle contraction provides a mechanical advantage to bolus transit during circular smooth muscle contraction. Esophageal striated muscle is directly controlled by neural circuits originating in the central nervous system, resulting in coordinated contractions. In contrast, the esophageal smooth muscle is controlled by enteric circuits modulated by extrinsic central neural connections resulting in neural relaxation and contraction. The esophageal muscles are modulated by sensory information arising from within the lumen. 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 identify the “mechanical states” of the circular muscle; that is when the muscles are passively or actively, relaxing or contracting. Detecting these changes in the mechanical state of the muscle has been difficult and as the current interpretation of esophageal motility is based largely upon pressure measurement (manometry), subtle changes in the muscle function during peristalsis can be missed. We hypothesized that quantification of mechanical states of the esophageal circular muscles and the pressure-diameter properties that define them, would allow objective characterization of the mechanisms that govern esophageal peristalsis. To achieve this we analyzed barium swallows captured by simultaneous videofluoroscopy and 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 comparable with measurements from videofluoroscopy. Our data indicated that identification of mechanical state of esophageal muscle was simple to apply and revealed patterns consistent with the known neural inputs activating the different muscles during swallowing.

High-resolution manometry combined with impedance measurements discriminates the cause of dysphagia in children

Pressure-flow analysis allows assessing esophageal bolus transport in relation to esophageal pressures. This study aimed to characterize pressure-flow metrics in relation to dysphagia in paediatric patients. We analysed esophageal pressure-impedance recordings of 5 ml liquid and viscous swallows from 35 children (17 M, mean 10.5 ± 0.8 years). Primary indication for referral was gastroesophageal reflux disease (GERD) (9), post-fundoplication dysphagia (5), idiopathic dysphagia (16), trachea-esophageal fistula (2) and other (3). Peristaltic function was assessed using the 20 mmHg iso-contour defect and the timing between bolus pressure and flow was assessed using the Pressure Flow Index, a metric elevated in relation to dysphagia. Patients were stratified in relation to dysphagia and to peristaltic defect size. Dysphagia was characterized by a weaker peristalsis for liquids and higher Pressure Flow Index for viscous. When patients were stratified based on weak or normal peristalsis, dysphagia with weak peristalsis related to a larger iso-contour defect size and dysphagia with normal peristalsis related to higher Pressure Flow Index.

CONCLUSION

Pressure-flow analysis enables differentiation of patients with dysphagia due to weak peristalsis (poor bolus clearance) from abnormal bolus flow resistance (esophageal outflow obstruction). This new dichotomous categorization of esophageal function may help guide the selection of optimal treatment such as pharmacological or endoscopic therapy.

WHAT IS KNOWN

• Pressure-flow analysis (PFA) can detect abnormalities in esophageal motility using integrated analysis of bolus propulsion and bolus flow during swallowing. • AIM analysis has recently been reported to be useful in identifying subtle pre-operative esophageal dysfunction in adult patients who developed post-fundoplication dysphagia as well as in patients with non-obstructive dysphagia.

WHAT IS NEW

• Pressure-flow parameters can distinguish the cause of dysphagia in paediatric patients. • Combined high-resolution manometry and impedance measurements with pressure-flow analysis can differentiate paediatric patients with dysphagia symptoms in relation to either weak peristalsis (poor bolus clearance) or over-pressurization (abnormal bolus flow resistance). HOW MIGHT IT IMPACT ON CLINICAL PRACTICE IN THE FUTURE? • This study supports the use of a novel objective analysis method on recordings that are readily used in paediatric clinical practice. • The pressure-flow approach allows discriminating esophageal dysfunction in relation to dysphagia symptoms in children. This has not been achieved in children with current analysis methods. • The new findings of this study allow a dichotomous categorization of esophageal function, which may help to guide the selection of the most optimal treatment such as pharmacological or endoscopic therapy.

Current advances in treatment of gastroparesis

INTRODUCTION

Gastroparesis is a syndrome defined by delayed gastric emptying in the absence of mechanical obstruction. Gastroparesis has significant symptomatology and negative impacts on the patient's quality of life.

AREAS COVERED

This article reviews current treatment options for gastroparesis, recent advances in treatment and future directions that treatment may head. Current options are broadly divided into prokinetics and symptom modulators. Within each group, current modalities as well as recent advances are discussed according to agent mechanism of action. Lastly, findings regarding the cellular pathophysiology involved in gastroparesis will be briefly reviewed along with their implications for future treatments.

EXPERT OPINION

The numerous motor functions and neural inputs that control gastric motility are complex and not fully understood. Our lack of understanding of its pathophysiology has led to treatment options which are empirical, palliative and often ineffective. Newly intensified interest in the cellular pathophysiology behind gastroparesis provides promise for a new era of treatments. Identification of common cellular changes in gastroparesis has provided targets for treatment that may allow us to one day better treat the symptoms of gastroparesis related to its underlying pathophysiology. This is the future of gastroparesis therapy.

Oesophageal dysphagia: manifestations and diagnosis

Oesophageal dysphagia is a common symptom, which might be related to severe oesophageal diseases such as carcinomas. Therefore, an organic process must be ruled out in the first instance by endoscopy in all patients presenting with dysphagia symptoms. The most prevalent obstructive aetiologies are oesophageal cancer, peptic strictures and eosinophilic oesophagitis. Eosinophilic oesophagitis is one of the most common causes of dysphagia in adults and children, thus justifying the need to obtain oesophageal biopsy samples from all patients presenting with unexplained dysphagia. With the advent of standardized high-resolution manometry and specific metrics to characterize oesophageal motility, the Chicago classification has become a gold-standard algorithm for manometric diagnosis of oesophageal motor disorders. In addition, sophisticated investigations and analysis methods that combine pressure and impedance measurement are currently in development. In the future, these techniques might be able to detect subtle pressure abnormalities during bolus transport, which could further explain pathophysiology and symptoms. The degree to which novel approaches will help distinguish dysphagia caused by motor abnormalities from functional dysphagia still needs to be determined.

Pressure-flow characteristics of normal and disordered esophageal motor patterns

OBJECTIVE

To perform pressure-flow analysis (PFA) in a cohort of pediatric patients who were referred for diagnostic manometric investigation.

STUDY DESIGN

PFA was performed using purpose designed Matlab-based software. The pressure-flow index (PFI), a composite measure of bolus pressurization relative to flow and the impedance ratio, a measure of the extent of bolus clearance failure were calculated.

RESULTS

Tracings of 76 pediatric patients (32 males; 9.1 ± 0.7 years) and 25 healthy adult controls (7 males; 36.1 ± 2.2 years) were analyzed. Patients mostly had normal motility (50%) or a category 4 disorder and usually weak peristalsis (31.5%) according to the Chicago Classification. PFA of healthy controls defined reference ranges for PFI ≤142 and impedance ratio ≤0.49. Pediatric patients with pressure-flow (PF) characteristics within these limits had normal motility (62%), most patients with PF characteristics outside these limits also had an abnormal Chicago Classification (61%). Patients with high PFI and disordered motor patterns all had esophagogastric junction outflow obstruction.

CONCLUSIONS

Disordered PF characteristics are associated with disordered esophageal motor patterns. By defining the degree of over-pressurization and/or extent of clearance failure, PFA may be a useful adjunct to esophageal pressure topography-based classification.

Correlation of esophageal pressure-flow analysis findings with bolus transit patterns on videofluoroscopy

Pressure-flow analysis quantifies the interactions between bolus transport and pressure generation. We undertook a pilot study to assess the interrelationships between pressure-flow metrics and fluoroscopically determined bolus clearance and bolus transport across the esophagogastric junction (EGJ). We hypothesized that findings of abnormal pressure-flow metrics would correlate with impaired bolus clearance and reduced flow across the EGJ. Videofluoroscopic images, impedance, and pressure were recorded simultaneously in nine patients with dysphagia (62-82 years, seven male) tested with liquid barium boluses. A 3.6 mm diameter solid-state catheter with 25 × 1 cm pressure/12 × 2 cm impedance was utilized. Swallowed bolus clearance was assessed using a validated 7-point radiological bolus transport scale. The cumulative period of bolus flow across the EGJ was also fluoroscopically measured (EGJ flow time). Pressure only parameters included the length of breaks in the 20 mmHg iso-contour and the 4 second integrated EGJ relaxation pressure (IRP4s). Pressure-flow metrics were calculated for the distal esophagus, these were: time from nadir impedance to peak pressure (TNadImp to PeakP) to quantify bolus flow timing; pressure flow index (PFI) to integrate bolus pressurization and flow timing; and impedance ratio (IR) to assess bolus clearance. When compared with controls, patients had longer peristaltic breaks, higher IRs, and higher residual EGJ relaxation pressures (break length of 8 [2, 13] vs. 2 [0, 2] cm, P = 0.027; IR 0.5 ± 0.1 vs. 0.3 ± 0.0, P = 0.019; IRP4s 11 ± 2 vs. 6 ± 1 mmHg, P = 0.070). There was a significant positive correlation between higher bolus transport scores and longer peristaltic breaks (Spearman correlation r = 0.895, P < 0.001) and with higher IRs (r = 0.661, P < 0.05). Diminished EGJ flow times correlated with a shorter TNadImp to PeakP (r = -0.733, P < 0.05) and a higher IR (r = -0.750, P < 0.05). Longer peristaltic breaks and higher IR correlate with failed bolus clearance on videofluoroscopy. The metric TNadImp to PeakP appears to be a marker of the period of time over which the bolus flows across the EGJ.

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.

Evaluating esophageal bolus transit by impedance monitoring

The function of the esophagus is transporting nutrients from the oropharyngeal cavity to the stomach. This is achieved by coordinated contractions and relaxation of the tubular esophagus and the upper and lower esophageal sphincter. Multichannel intraluminal impedance monitoring offers quantification of esophageal bolus transit and/or retention without the use of ionizing radiation. Combined with conventional or high-resolution manometry, impedance measurements complement the quantification of esophageal body contraction and sphincter relaxation, offering a more comprehensive evaluation of esophageal function. Further studies evaluating the utility of quantifying bolus transit will help clarify the role and position of impedance measurements.

Esophageal function testing: beyond manometry and impedance

Manometry and impedance provide only surrogate information regarding longitudinal wall function and are focused on contractile amplitude and lumen content. Ultrasound imaging provides a unique perspective of esophageal function by providing important information regarding longitudinal muscle contraction. Laser Doppler assessment of perfusion may be an important complementary tool to assess abnormal wall blood perfusion as a possible mechanism of pain.

The four phases of esophageal bolus transit defined by high-resolution impedance manometry and fluoroscopy

We aimed to model esophageal bolus transit based on esophageal pressure topography (EPT) landmarks, concurrent intrabolus pressure (IBP), and esophageal diameter as defined with fluoroscopy. Ten healthy subjects were studied with high-resolution impedance manometry and videofluoroscopy. Data from four 5-ml barium swallows (2 upright, 2 supine) in each subject were analyzed. EPT landmarks were utilized to divide bolus transit into four phases: phase I, upper esophageal sphincter (UES) opening; phase II, UES closure to the transition zone (TZ); phase III, TZ to contractile deceleration point (CDP); and phase IV, CDP to completion of bolus emptying. IBP and esophageal diameter were analyzed to define functional differences among phases. IBP exhibited distinct changes during the four phases of bolus transit. Phase I was associated with filling via passive dilatation of the esophagus and IBP reflective of intrathoracic pressure. Phase II was associated with auxotonic relaxation and compartmentalization of the bolus distal to the TZ. During phase III, IBP exhibited a slow increase with loss of volume related to peristalsis (auxotonic contraction) and passive dilatation in the distal esophagus. Phase IV was associated with the highest IBP and exhibited isometric contraction during periods of nonemptying and auxotonic contraction during emptying. IBP may be used as a marker of esophageal wall state during the four phases of esophageal bolus transit. Thus abnormalities in IBP may identify subtypes of esophageal disease attributable to abnormal distensibility or neuromuscular dysfunction.

Flow time through esophagogastric junction derived during high-resolution impedance-manometry studies: a novel parameter for assessing esophageal bolus transit

This study aimed to develop and validate a method to measure bolus flow time (BFT) through the esophagogastric junction (EGJ) using a high-resolution impedance-manometry (HRIM) sleeve. Ten healthy subjects were studied with concurrent HRIM and videofluoroscopy; another 15 controls were studied with HRIM alone. HRIM studies were performed using a 4.2-mm-outer diameter assembly with 36 pressure sensors at 1-cm intervals and 18 impedance segments at 2-cm intervals (Given Imaging, Los Angeles, CA). HRIM and fluoroscopic data from four barium swallows, two in the supine and two in the upright position, were analyzed to create a customized MATLAB program to calculate BFT using a HRIM sleeve comprising three sensors positioned at the crural diaphragm. Bolus transit through the EGJ measured during blinded review of fluoroscopy was almost identical to BFT calculated with the HRIM sleeve, with the nadir impedance deflection point used as the signature of bolus presence. Good correlation existed between videofluoroscopy for measurement of upper sphincter relaxation to beginning of flow [R = 0.97, P < 0.001 (supine) and R = 0.77, P < 0.01 (upright)] and time to end of flow [R = 0.95, P < 0.001 (supine) and R = 0.82, P < 0.01 (upright)]. The medians and interquartile ranges (IQR) of flow time though the EGJ in 15 healthy subjects calculated using the virtual sleeve were 3.5 s (IQR 2.3-3.9 s) in the supine position and 3.2 s (IQR 2.3-3.6 s) in the upright position. BFT is a new metric that provides important information about bolus transit through the EGJ. An assessment of BFT will determine when the EGJ is open and will also provide a useful method to accurately assess trans-EGJ pressure gradients during flow.

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.

Oesophageal pressure-flow metrics in relation to bolus volume, bolus consistency, and bolus perception

BACKGROUND

The utility of combined oesophageal pressure-impedance recording has been enhanced by automation of data analysis.

OBJECTIVE

To understand how oesophageal function as measured by automated impedance manometry (AIM) pressure-flow analysis varies with bolus characteristics and subjective perception of bolus passage.

METHODS

Oesophageal pressure-impedance recordings of 5 and 10 ml liquid or viscous swallows and 2 and 4 cm solid swallows from 20 healthy control subjects (five male; 25-73 years) were analysed. Metrics indicative of bolus pressurization (intrabolus pressure and intrabolus pressure slope) were derived. Bolus flow resistance, the relationship between bolus pressurization and flow timing, was assessed using a pressure-flow index. Bolus retention was assessed using the ratio of nadir impedance to peak pressure impedance (impedance ratio). Subjective perception of bolus passage was assessed swallow by swallow.

RESULTS

Viscosity increased the bolus flow resistance and reduced bolus clearance. Responses to boluses of larger volume and more viscous consistency revealed a positive correlation between bolus pressurization and oesophageal peak pressure. Flow resistance was higher in subjects who perceived bolus hold up of solids.

CONCLUSIONS

Bolus volume and bolus type alter oesophageal function and impact AIM analysis metrics descriptive of oesophageal function. Perception of bolus transit was associated with heightened bolus pressurization relative to bolus flow.

New insights in gastroesophageal reflux, esophageal function and gastric emptying in relation to dysphagia before and after anti-reflux surgery in children

In children with gastroesophageal reflux (GER) disease refractory to pharmacological therapies, anti-reflux surgery (fundoplication) may be a treatment of last resort. The applicability of fundoplication has been hampered by the inability to predict which patient may benefit from surgery and which patient is likely to develop post-operative dysphagia. pH impedance measurement and conventional manometry are unable to predict dysphagia, while the role of gastric emptying remains poorly understood. Recent data suggest that the selection of patients who will benefit from surgery might be enhanced by automated impedance manometry pressure-flow analysis (AIM) analysis, which relates bolus movement and pressure generation within the esophageal lumen.

Inter- and intra-rater reproducibility of automated and integrated pressure-flow analysis of esophageal pressure-impedance recordings

BACKGROUND

Automated impedance manometry pressure-flow analysis (AIM analysis) determines pressure measurements relative to bolus flow and has to date shown subtle variations in esophageal motility in relation to dysphagia. In this study, we assessed intra- and inter-rater reproducibility of AIM metrics derived using purpose designed software.

METHODS

Fifty patients referred for evaluation of gastro-esophageal reflux symptoms (33 men, age 52 ± 1.9 years) underwent combined high-resolution impedance manometry and completed a dysphagia questionnaire. From 10 liquid and 10 viscous swallows, a subset of four swallows (two saline and two viscous) was systematically selected from each patient for manual and AIMplot analysis, which was performed twice by five observers (two experts, three non-experts). Intra- and inter-rater agreement were determined using intraclass correlation coefficients.

KEY RESULTS

AIMplot-based analysis showed high intra-rater and inter-rater reproducibility for all metrics (mean ICCs of 0.95 and 0.94, respectively). Reproducibility of metrics derived for liquid and viscous did not differ (ICCs of 0.96 and 0.91 for liquid and viscous, respectively). In addition, metrics derived by experts had an equivalent level of reproducibility compared to non-experts (ICCs of 0.96 and 0.94, respectively). Variables that could be derived with commercial software (ManoView™) correlated highly with variables from AIMplot-based analysis, such as 4-s integrated relaxation pressure (r = 0.85) and the 20-mmHg isobaric contour defect (r = 0.92).

CONCLUSIONS & INFERENCES

Esophageal AIM analysis is highly reproducible, independent of an observer's level of experience in esophageal motility. Therefore, AIM analysis produces data that are reliable for clinical and research purposes.