Neoplastic progression in short-segment Barrett's oesophagus is associated with impairment of chemical clearance, but not inadequate acid suppression by proton pump inhibitor therapy

Esophageal secondary peristalsis following acid infusion and chemical clearance correlate with mucosal integrity and acid sensitivity in GERD patients

Background

Acid sensitivity can be altered in patients with gastroesophageal reflux disease (GERD). Secondary peristalsis helps clear gastro-esophageal refluxate and residual ingested food bolus.

Objectives

The aim of this study was to investigate the associations among acid sensitivity, esophageal mucosal integrity, chemical clearance, and secondary peristalsis before and after esophageal acid infusion.

Design

This was an investigator-initiated, prospective, cross-sectional study.

Methods

Adult reflux patients underwent high resolution manometry and 24 h impedance-pH monitoring off acid suppression to identify GERD phenotypes, including non-erosive reflux disease (NERD), reflux hypersensitivity (RH), and functional heartburn (FH). Secondary peristalsis was assessed using five rapid 20 mL air injections into the esophagus before and after infusion of hydrochloric acid (0.1 N) into the mid-esophagus. Conventional acid infusion parameters recorded included lag time, intensity rating, and sensitivity score. Chemical clearance was evaluated using the post-reflux swallow-induced peristaltic wave (PSPW), and mucosal integrity was assessed by the mean nocturnal baseline impedance (MNBI) derived from impedance-pH monitoring.

Results

A total of 88 patients (age 21-64 years, 62.5% women) completed the study including 12 patients with NERD, 45 with RH, and 31 with FH. There was no significant difference in acid infusion parameters between patients with NERD, RH, and FH. Upon acid infusion, patients who exhibited successful secondary peristalsis had longer lag time, higher MNBI, and shorter bolus contact time than those without secondary peristalsis. Meanwhile, patients with intact PSPW demonstrated significantly higher intensity ratings in response to acid perfusion and higher MNBI than those with impaired PSPW. The lag time correlated positively with MNBI (r = 0.285; p = 0.007).

Conclusion

In conclusion, the protective effect of esophageal secondary peristalsis and chemical clearance on esophageal mucosal integrity was demonstrated. Concerning acid sensitivity, longer lag time in patients with intact secondary peristalsis may be attributed to better esophageal mucosal integrity, while stronger intensity ratings may have a greater tendency to induce PSPW and protect esophageal mucosal integrity.

Association between post-reflux swallow-induced peristaltic wave index and esophageal mucosal integrity in patients with GERD symptoms

BACKGROUND

Impedance-pH monitoring allows evaluation of esophageal chemical clearance, a response to reflux elicited by the esophago-salivary reflex, by means of the post-reflux swallow-induced peristaltic wave (PSPW) index; mucosal integrity can be evaluated by means of mean nocturnal baseline impedance (MNBI) and is regarded as a GERD marker. Currently, the relationship between PSPW index and MNBI has not yet been fully investigated and represents the aim of the present study.

METHODS

Impedance-pH tracings from consecutive patients were reviewed. ROC analysis and multivariate regression models were generated to evaluate the association between acid exposure time (AET), total refluxes (TRs), PSPW index, and MNBI. Patients were classified by means of AET thresholds and symptom-reflux association indexes into conclusive and inconclusive GERD, reflux hypersensitivity (RH), and functional heartburn (FH). Pathologic MNBI <2292 Ω was defined according to published outcome studies.

KEY RESULTS

Two hundred and thirty patients constituted the study cohort. Overall, a significant direct correlation was observed between PSPW index and MNBI (0.759, p < 0.001). At ROC analysis, a PSPW index cut-off value of 53% was the best discriminator between normal from pathologic MNBI values (sensitivity 88%, specificity 86.4%). Considering AET cut-off of 4% or 6%, a sensitivity of 80.7% and 46% and a specificity of 62.5% and 93.2% were found, respectively. According to multivariate analysis, AET >4% and PSPW index value <53% or <61% were significantly associated with pathologic MNBI values.

CONCLUSIONS AND INFERENCES

Esophageal chemical clearance is a major defense mechanism against reflux and its impairment represents a major determinant of reflux-associated mucosal damage.

Novel Advanced Impedance Metrics on Impedance-pH Testing Predict Lung Function Decline in Idiopathic Pulmonary Fibrosis

INTRODUCTION

Gastroesophageal reflux has been associated with idiopathic pulmonary fibrosis (IPF). Mean nocturnal baseline impedance (MNBI) is a marker of esophageal mucosal integrity, whereas postreflux swallow-induced peristaltic wave (PSPW) index reflects esophageal chemical clearance. Both metrics offer novel ways to assess reflux burden on multichannel intraluminal impedance-pH testing (MII-pH), but their role in extraesophageal reflux remains unclear. We aimed to evaluate the relationship between these novel metrics and lung function decline in patients with IPF.

METHODS

Adults with IPF undergoing prelung transplant MII-pH were enrolled. All patients completed pulmonary function testing (PFT) at the time of MII-pH and at the 1-year follow-up. MNBI was calculated by averaging baseline impedance at three 10-minute intervals (1 AM/2 AM/3 AM). PSPW index was the proportion of all reflux episodes, followed by a peristaltic swallow within 30 seconds. Univariate (Student t-test/Pearson correlation) and multivariable (general linear regression) analyses were performed.

RESULTS

One hundred twenty-five subjects (mean age = 61.7 years, 62% men) were included. Forced expiratory volume in one second and forced vital capacity declined more significantly over 12 months in subjects with lower distal MNBI, proximal MNBI, and PSPW index (all P < 0.05). On multivariable analyses adjusting for age, sex, proton pump inhibitor use, and baseline lung function, distal MNBI (β = -10.86, P = 0.024; β = -8.03, P = 0.045), proximal MNBI (β = -13.5, P = 0.0068; β = -9.80, P = 0.025), and PSPW index (β = -18.1, P = 0.010; β = -12.55, P = 0.050) remained predictive of greater forced expiratory volume in one second and forced vital capacity decline.

DISCUSSION

Low distal MNBI, proximal MNBI, and PSPW index independently predicted more severe lung function decline over 1 year in patients with IPF. These impedance metrics may have prognostic value and support a role for reflux in IPF pathogenesis.

Reflux characteristics triggering post-reflux swallow-induced peristaltic wave (PSPW) in patients with GERD symptoms

BACKGROUND

Esophageal chemical clearance has been evaluated with the post-reflux swallow-induced peristaltic wave (PSPW) index. The factors triggering PSPW in Gastro-esophageal reflux disease (GERD) have not yet been investigated. This multicenter study was aimed at evaluating the characteristics of reflux episodes associated with PSPW occurrence in patients with typical GERD symptoms.

METHODS

Impedance-pH tracings from patients with typical reflux symptoms were analyzed. Sixteen healthy subjects were included for comparison. Multivariate analysis was performed to determine predictors of PSPW events.

KEY RESULTS

Impedance-pH tracings from 60 patients and 16 healthy subjects were evaluated. A total of 3454 refluxes were recorded. In patients, comparing reflux episodes followed with those not followed by a PSPW, significantly higher proportions of acid (79% vs. 74%, p: 0.02), mixed (47% vs. 32%, p: 0.0001) and proximal refluxes (34% vs. 20%, p: 0.0001) were observed. A multivariate analysis, acid (OR: 1.3, 95% CI: 1.05-1.6), mixed (OR: 2, 95% CI: 1.6-2.3), and proximal (OR: 2.1, 95% CI: 1.7-2.5) refluxes were independently associated with PSPWs. Reflux episodes followed by a PSPW were characterized by a significantly higher bolus clearing time [(mean ± SD) 41 s ± 6 s vs. 30 s ± 5 s, p < 0.05] whereas nadir pH value of reflux events preceding PSPWs was tangentially but not significantly lower [(mean ± SD) 2.61 ± 1.22 vs. 2.74 ± 1.26, p: 0.057].

CONCLUSIONS AND INFERENCES

Acid, mixed and proximal refluxes, and their duration are key factors in eliciting PSPWs. PSPW represents a response to reflux directly related to the potential harmfulness of reflux contents.

Clinical use of mean nocturnal baseline impedance and post-reflux swallow-induced peristaltic wave index for the diagnosis of gastro-esophageal reflux disease

The clinical diagnosis of gastro-esophageal reflux disease (GERD) is based on the presence of typical esophageal troublesome symptoms. In clinical practice, heartburn relief following a proton pump inhibitor (PPI) trial or endoscopy can confirm a diagnosis of GERD. In cases of diagnostic uncertainty or before anti-reflux interventions, combined impedance-pH monitoring (MII-pH) provides a comprehensive assessment of both physical and chemical properties of the refluxate, allowing to achieve a conclusive diagnosis of GERD. Recently, the Lyon Consensus proposed the use of mean nocturnal baseline impedance (MNBI) and post-reflux swallow-induced peristaltic wave index (PSPW-I) as novel MII-pH metrics to support the diagnosis of GERD. The calculation of MNBI and PSPW-I currently needs to be performed manually, but artificial intelligence systems for the automated analysis of MII-pH tracings are being developed. Several studies demonstrated the increased diagnostic yield MNBI and PSPW-I for the categorization of patients with GERD at both on- and off-PPI MII-pH monitoring. Accordingly, we performed a narrative review on the clinical use and diagnostic yield of MNBI and PSPW-I when the diagnosis of GERD is uncertain. Based on currently available evidence, we strongly support the evaluation of PSPW-I and MNBI as part of the standard assessment of MII-pH tracings for the evaluation of GERD, especially in patients with endoscopy-negative heartburn.

Postreflux swallow-induced peristaltic wave index from pH-impedance monitoring associates with esophageal body motility and esophageal acid burden

BACKGROUND

Postreflux swallow-induced peristaltic wave (PSPW) on pH-impedance monitoring and contraction vigor on high-resolution manometry (HRM) both assess esophageal peristaltic response. We aimed to evaluate relationships between PSPW and esophageal peristalsis on HRM in the context of reflux disease in this multicenter cohort study.

METHODS

pH-impedance and HRM studies performed on patients with persisting reflux symptoms were reviewed from 6 centers (5 in Europe and 1 in US). Total, upright and supine acid exposure time (AET) were evaluated from pH-impedance studies; PSPW index (PSPWI) and mean nocturnal baseline impedance (MNBI) were calculated using standard methodology. Esophageal body contraction vigor was analyzed using distal contractile integral (DCI), and DCI ratio > 1 between single swallows and multiple rapid swallows (MRS) defined presence of contraction reserve. Student's t test, ANOVA, and linear regression were utilized to investigate relationships between PSPW, contraction vigor, and contraction reserve.

KEY RESULTS

Of 296 patients (52.8 ± 0.8 yr, 63% F), median PSPWI was 0.475. Only 24.0% had intact DCI; the remainder had varying degrees of hypomotility. As hypomotility increased, PSPWI and MNBI decreased significantly, while total AET and reflux episodes had an inverse response (P ≤ .002 for each). MRS data were available in 167 (56.4%), 72.5% had contraction reserve. MRS cohorts with normal PSPWI had significantly lower reflux burden compared to low PSPWI, regardless of presence or absence of contraction reserve (P ≤ .001).

CONCLUSIONS AND INFERENCES

PSPWI correlates with esophageal hypomotility and reflux burden, and complements clinical reflux evaluation. Intact PSPW is more relevant to esophageal reflux clearance than contraction reserve.

Esophageal physiology-an overview of esophageal disorders from a pathophysiological point of view

The esophagus serves the principal purpose of transporting food from the pharynx into the stomach. A complex interplay between nerves and muscle fibers ensures that swallowing takes place as a finely coordinated event. Esophageal function can be tested by a variety of methods, endoscopy, manometry, and reflux monitoring being some of the most important. Regarding pathophysiology, motor disorders, such as achalasia, often cause dysphagia and/or chest pain. Functional esophageal disorders are a heterogeneous group with hypersensitivity as a dominant pathophysiological factor. Gastroesophageal reflux disease often causes symptoms, such as heartburn and regurgitation, and a spectrum of disease, ranging from minimal mucosal damage visible only in the microscope to esophageal ulcers and strictures in the most severe cases. Eosinophilic esophagitis is an immune-mediated condition that can result in significant dysphagia and associated luminal narrowing. In the following, we will provide an overview of the most common esophageal disorders from a combined pathophysiological and clinical view.

Esophageal Function Abnormalities in Patients With Barrett's Esophagus

Various esophageal functional abnormalities have been described in patients with Barrett's esophagus (BE). A significantly higher esophageal acid exposure especially in the supine position has been documented in BE, as compared with the other gastroesophageal reflux disease phenotypes. In addition, weakly acidic reflux and duodenogastroesophageal reflux are more common in BE patients. The presence of Barrett's mucosa reduces esophageal mucosal impedance, occasionally to a level that prevents detection of reflux episodes. Reduced amplitude contractions and lower esophageal sphincter basal pressure are more common in BE patients as compared with the other gastroesophageal reflux disease groups. Ineffective esophageal motility is the most commonly defined motor disorder in BE. Reduced chemoreceptor and mechanoreceptor sensitivity to acid and balloon distention, respectively, have been suggested to explain lack or significantly less reports of reflux-related symptoms by BE patients.

Mucosal impedance for esophageal disease: evaluating the evidence

Impedance has traditionally been employed in esophageal disease as a means to assess bolus flow and reflux episodes. Recent and ongoing research has provided new and novel applications for this technology. Measurement of esophageal mucosal impedance, via either multichannel intraluminal impedance catheters or specially designed endoscopically deployed impedance catheters, provides a marker of mucosal integrity. Mucosal impedance has been shown to segregate gastroesophageal reflux disease (GERD) and eosinophilic esophagitis from non-GERD controls and may play a role in predicting response to reflux intervention. More data are needed with regard to other esophageal subgroups, outcome studies, and functional disease. Our paper reviews the history of impedance in esophageal disease, the means of assessing baseline and mucosal impedance, data with regard to the newly developed mucosal impedance probes, the clinical utility of mucosal impedance in specific clinical conditions, and limitations in our existing knowledge, along with suggestions for future studies.

Post-reflux swallow-induced peristaltic wave (PSPW): physiology, triggering factors and role in reflux clearance in healthy subjects

BACKGROUND AND AIMS

The underlying physiology of post-reflux swallow-induced peristaltic wave (PSPW) is unclear. We aimed to: 1) calculate the probability of a random association between reflux and PSPW; 2) characterize factors that could underlie triggering of PSPW and 3) assess the chemical clearance effect of PSPW in healthy asymptomatic subjects.

METHODS

A total of 251 impedance-pH tracings from healthy asymptomatic subjects were analysed. Twenty consecutive tracings from this pool with 20-40 reflux episodes/24 h and a PSPW index higher than 50% were separately analyzed to evaluate the probability of a random association between reflux and PSPW. The characteristics of reflux episodes followed by a PSPW were compared with those not associated with PSPW.

RESULTS

A mean time interval of 29.3 s between a reflux episode and the first swallow captured 71% of total reflux episodes, and 67% of accompanying swallows were non-random. Compared to reflux without PSPW, reflux episodes with PSPW were more frequently acidic (P = 0.048), mixed with gas (P < 0.0001), of high proximal extent (P < 0.0001), while awake (P < 0.0001), and with shorter chemical clearance time (P = 0.040). High proximal extent, gas presence and occurring while awake were independent factors associated with PSPW (P < 0.0001).

CONCLUSION

Using a time window between reflux and PSPW of around 30 s, the probability of a chance association is around 30%. Reflux episodes with high proximal extent, containing gas and occurring while awake are important factors associated with PSPW in healthy subjects. Reflux episodes with PSPW have a shorter chemical clearance time.

Esophageal pH-impedance monitoring in children: position paper on indications, methodology and interpretation by the SIGENP working group

Multichannel intraluminal impedance pH (MII-pH) monitoring currently represents the gold standard diagnostic technique for the detection of gastro-esophageal reflux (GER), since it allows to quantify and characterize all reflux events and their possible relation with symptoms. Over the last ten years, thanks to its strengths and along with the publication of several clinical studies, its worldwide use has gradually increased, particularly in infants and children. Nevertheless, factors such as the limited pediatric reference values and limited therapeutic options still weaken its current clinical impact. Through an up-to-date review of the available scientific evidence, our aim was to produce a position paper on behalf of the working group on neurogastroenterology and acid-related disorders of the Italian Society of Pediatric Gastroenterology, Hepatology and Nutrition (SIGENP) on MII-pH monitoring technique, indications and interpretation in pediatric age, in order to standardise its use and to help clinicians in the diagnostic approach to children with GER symptoms.

PROLONGED GASTROESOPHAGEAL REFLUX MONITORING BY IMPEDANCE-PHMETRY: A REVIEW OF THE SUBJECT PONDERED WITH OUR EXPERIENCE WITH 1,200 CASES

BACKGROUND

Prolonged monitoring increased our knowledge on gastroesophageal reflux (GER), and the disease became known as gastroesophageal reflux disease (GERD). Prolonged reflux monitoring permits the diagnosis of GERD when endoscopic findings are not enough to characterize it.

OBJECTIVE

The objective of this paper is to review the current knowledge on impedance-pH monitoring, taking into account the published literature and the authors experience with 1,200 exams.

METHODS

The different types of prolonged reflux monitoring, namely: conventional pHmetry, catheter-free pHmetry and impedance-pHmetry will be briefly described. The new possibilities of evaluation with impedance-pHmetry are emphasized, namely: the study of symptomatic patients in use of proton pump inhibitors (PPIs); evaluation of patients with symptoms suggestive of GERD although with normal endoscopy and normal pHmetry, diagnostic elucidation of patients with atypical symptoms or supra-esophageal symptoms, mainly chronic cough, study of patients complaining of belch, differentiating gastric and supra-gastric belching, and the proper work-up before anti-reflux surgery.

RESULTS

When impedance was associated to pH monitoring, an impressive technological evolution became apparent, when compared to pH monitoring alone. The main advantages of impedance-pHmetry are: the ability to detect all types of reflux: acid, non-acid, liquid, gaseous. In addition, other important measurements can be made: the ability of the esophagus in transporting the bolus, the measurement of basal mucosal impedance and the evaluation of primary peristalsis post reflux.

CONCLUSION

Impedance-pHmetry is a promising method, with great advantages over conventional pHmetry. The choice between these two types of monitoring should be very judicious. The authors suggest the importance of careful evaluation of each reflux episode by the physician responsible for the examination, necessary for the correct interpretation of the tracings.

The role of esophageal pH-impedance testing in clinical practice

PURPOSE OF REVIEW

Ambulatory reflux monitoring is typically performed when esophageal symptoms do not respond to usual antireflux medications, or prior to invasive antireflux therapy. Although pH-based metrics have been the standard in defining esophageal reflux burden, novel impedance parameters have been introduced in recent years that can either be extracted from pH-impedance monitoring or obtained directly from esophageal mucosa. This review evaluates the clinical role of esophageal pH-impedance monitoring in clinical practice in the present day.

RECENT FINDINGS

Elevated acid exposure time in the distal esophagus remains the primary metric that predicts symptom improvement from antireflux therapy. Although conventional impedance-based metrics (numbers of reflux episodes, reflux-symptom association) provide complementary evidence, novel impedance-based metrics show promise in documenting reflux-induced damage to esophageal mucosal integrity, and in potentially predicting treatment outcome. The postreflux swallow-induced peristaltic wave measures integrity of primary peristalsis triggered by a reflux episode. Baseline impedance values reflect histopathological damage to mucosal integrity, and improve following successful antireflux therapy. Mucosal impedance assessed at endoscopy is a new diagnostic tool that is currently being evaluated in multinational research studies.

SUMMARY

Esophageal pH-impedance monitoring has potential to augment confidence in a reflux diagnosis beyond that provided by pH-monitoring alone.

Lack of improvement of impaired chemical clearance characterizes PPI-refractory reflux-related heartburn

OBJECTIVE

Heartburn is the most specific symptom of reflux disease and is highly responsive to proton pump inhibitor (PPI) therapy. Some patients do not respond to PPIs, but mechanisms of refractoriness have not yet been fully elucidated. Impedance-pH monitoring, allowing comprehensive on-therapy assessment of reflux, represents a valuable test to investigate PPI refractoriness.

METHODS

Prospective multicenter study comparing endoscopy-negative patients with PPI-refractory and PPI-responsive heartburn. Reflux disease was demonstrated by off-PPI impedance-pH monitoring and mechanisms of refractoriness were studied with on-PPI impedance-pH monitoring. Assessment of impedance-pH tracings comprised conventional parameters, post-reflux swallow-induced peristaltic wave (PSPW) index, and mean nocturnal baseline impedance (MNBI).

RESULTS

Sixty-four patients entered the study, 32 with PPI-refractory and 32 with PPI-responsive heartburn. On PPI, median percentage gastric and esophageal acid exposure time and number of acid refluxes did not differ between the two groups; conversely, number of total and weakly acidic refluxes and percentage bolus exposure were significantly higher while PSPW index and MNBI were significantly lower in PPI-refractory cases. At multivariate logistic regression analysis, PSPW index was the sole independent risk factor for PPI refractoriness (OR 1.082, 95% CI 1.022-1.146, P = 0.007). Comparing off- and on-PPI parameters, median PSPW index did not change in PPI-refractory patients (24% vs. 26%, P = 0.327) but increased significantly in PPI-responsive cases (29% vs. 46%, P < 0.001).

CONCLUSIONS

Lack of improvement of impaired chemical clearance is a major determinant of PPI refractoriness. Timely post-reflux salivary swallowing represents a key defensive mechanism and a potential target for future treatment modalities in PPI-refractory reflux-related heartburn.

Superficial Esophageal Mucosal Afferent Nerves May Contribute to Reflux Hypersensitivity in Nonerosive Reflux Disease

BACKGROUND & AIMS

Little is known about the causes of heartburn in patients with gastro-esophageal reflux disease. Visible epithelial damage is seldom associated with symptom severity, evidenced by the significant symptom burden in patients with nonerosive reflux disease (NERD) compared with patients with erosive reflux disease (ERD) or Barrett's esophagus (BE). We studied the distribution of mucosal nerve fibers in patients with NERD, ERD, and BE, and compared the results with those of healthy subjects.

METHODS

We performed a prospective study of 13 patients with NERD, 11 patients with ERD, and 16 patients with BE undergoing endoscopic evaluation in the United Kingdom or Greece. Biopsies were obtained from the proximal and distal esophageal mucosa of patients with NERD, from the distal esophageal mucosa of patients with ERD, and the distal-most squamous epithelium of patients with BE. These were examined for the presence and location of nerve fibers that reacted with a labeled antibody against calcitonin gene-related peptide (CGRP), a marker of nociceptive sensory nerves. The results were compared with those from 10 healthy volunteers (controls).

RESULTS

The distribution of CGRP-positive nerves did not differ significantly between the distal esophageal mucosa of controls (median, 25.5 cell layers to surface; interquartile range [IQR], 21.4-28.8) vs patients with ERD (median, 23 cell layers to surface; IQR, 16-27.5), or patients with BE (median, 21.5 cell layers to surface; IQR, 16.1-27.5). However, CGRP-positive nerves were significantly more superficial in mucosa from patients with NERD-both distal (median, 9.5 cell layers to surface; IQR, 1.5-13.3; P < .0001 vs ERD, BE, and controls) and proximal (median, 5.0 cell layers to surface; IQR, 2.5-9.3 vs median 10.4 cell layers to surface; IQR, 8.0-16.9; P = .0098 vs controls).

CONCLUSIONS

Proximal and distal esophageal mucosa of patients with NERD have more superficial afferent nerves compared with controls or patients with ERD or BE. Acid hypersensitivity in patients with NERD might be partially explained by the increased proximity of their afferent nerves to the esophageal lumen, and therefore greater exposure to noxious substances in refluxate.

Impedance-pH Monitoring for Diagnosis of Reflux Disease: New Perspectives

Heartburn is the most specific symptom of gastroesophageal reflux disease (GERD). In clinical practice, heartburn relief by a proton pump inhibitor (PPI) trial does suffice to confirm GERD. However, an objective diagnosis of GERD is required before anti-reflux endoscopic or surgical interventions, independently from PPI response. Thus, since normal findings at upper endoscopy are detected in the majority of patients with heartburn, reflux monitoring is often required. When traditional catheter-based or wireless pH tests are used, reflux episodes are conventionally identified by pH drops below 4.0 units. Combined impedance-pH monitoring has the advantage to provide a comprehensive assessment of both physical and chemical properties of refluxate and the distinction between acid and weakly acidic refluxes, both proven to cause heartburn. Unfortunately, the conventional impedance-pH parameters, namely acid exposure time and number of reflux events, are characterized by suboptimal diagnostic sensitivity, and the reliability of symptom-reflux association indexes remains questionable. Therefore, novel impedance parameters, namely the post-reflux swallow-induced peristaltic wave (PSPW) index and the mean nocturnal baseline impedance (MNBI), have recently been proposed in order to achieve a better diagnostic yield. In fact, they proved to be highly accurate in distinguishing reflux-related from reflux-unrelated heartburn, off- as well as on-PPI therapy. Currently, manual review of impedance-pH tracings is needed because of the modest accuracy of available software tools for automated analysis. PSPW index and MNBI are highly applicable and reproducible, and their calculation requires a few additional minutes during the manual review of impedance-pH tracings. So far, we believe that PSPW index and MNBI are ready for prime time and should become part of the standard analysis of impedance-pH tracings for GERD diagnosis in patients with endoscopy-negative heartburn.

Impairment of chemical clearance and mucosal integrity distinguishes hypersensitive esophagus from functional heartburn

BACKGROUND

Hypersensitive esophagus (HE) is defined by endoscopy-negative heartburn with a normal acid exposure time but positive symptom association probability (SAP) and/or symptom index (SI) on impedance-pH monitoring, and proton pump inhibitor (PPI) responsiveness. Functional heartburn (FH) is distinguished by negative SAP/SI and PPI refractoriness. The clinical value of SAP and SI has been questioned. We aimed to investigate whether impairment of chemical clearance and of mucosal integrity, expressed by the postreflux swallow-induced peristaltic wave (PSPW) index and the mean nocturnal baseline impedance (MNBI), characterize HE independently of SAP and SI.

METHODS

Impedance-pH tracings from PPI-responsive endoscopy-negative patients, 125 with nonerosive reflux disease and 108 with HE, distinguished by an abnormal and a normal acid exposure time, and from 70 patients with FH were retrospectively selected and blindly reviewed.

RESULTS

The mean PSPW index and MNBI were significantly lower in nonerosive reflux disease (30 %, 1378 Ω) than in HE (51 %; 2274 Ω) and in both of them as compared with FH (76 %; 3445 Ω) (P = 0.0001). Both the PSPW index (adjusted odds ratio 0.863, P = 0.001) and the MNBI (adjusted odds ratio 0.998, P = 0.001) were independent predictors of HE; with their combined assessment, the area under the curve on receiver operating characteristic analysis was 0.957. SAP and/or SI was positive in 67 of the 108 HE patients (62 %), whereas the PSPW index and/or MNBI was abnormal in 99 of the 108 HE patients (92 %; P < 0.0001).

CONCLUSIONS

HE is characterized by impairment of chemical clearance and mucosal integrity, which explains the increased reflux perception. When SAP and SI afford uncertain results, the PSPW index and MNBI should be analyzed.

Esophageal Acid Clearance During Random Swallowing Is Faster in Patients with Barrett's Esophagus Than in Healthy Controls

Background/Aims

Impaired esophageal acid clearance may be a contributing factor in the pathogenesis of Barrett’s esophagus. However, few studies have measured acid clearance as such in these patients. In this explorative, cross-sectional study, we aimed to compare esophageal acid clearance and swallowing rate in patients with Barrett’s esophagus to that in healthy controls.

Methods

A total of 26 patients with histology-confirmed Barrett’s esophagus and 12 healthy controls underwent (1) upper endoscopy, (2) an acid clearance test using a pH-impedance probe under controlled conditions including controlled and random swallowing, and (3) an ambulatory pH-impedance measurement.

Results

Compared with controls and when swallowing randomly, patients cleared acid 46% faster (P = 0.008). Furthermore, patients swallowed 60% more frequently (mean swallows/minute: 1.90 ± 0.74 vs 1.19 ± 0.58; P = 0.005), and acid clearance time decreased with greater random swallowing rate (P < 0.001). Swallowing rate increased with lower distal esophageal baseline impedance (P = 0.014). Ambulatory acid exposure was greater in patients (P = 0.033), but clearance times assessed from the ambulatory pH-measurement and acid clearance test were not correlated (all P > 0.3).

Conclusions

More frequent swallowing and thus faster acid clearance in Barrett’s esophagus may constitute a protective reflex due to impaired mucosal integrity and possibly acid hypersensitivity. Despite these reinforced mechanisms, acid clearance ability seems to be overthrown by repeated, retrograde acid reflux, thus resulting in increased esophageal acid exposure and consequently mucosal changes.

Barrett’s esophagus in 2016: From pathophysiology to treatment

Esophageal complications caused by gastroesophageal reflux disease (GERD) include reflux esophagitis and Barrett’s esophagus (BE). BE is a premalignant condition with an increased risk of developing esophageal adenocarcinoma (EAC). The carcinogenic sequence may progress through several steps, from normal esophageal mucosa through BE to EAC. A recent advent of functional esophageal testing (particularly multichannel intraluminal impedance and pH monitoring) has helped to improve our knowledge about GERD pathophysiology, including its complications. Those findings (when properly confirmed) might help to predict BE neoplastic progression. Over the last few decades, the incidence of EAC has continued to rise in Western populations. However, only a minority of BE patients develop EAC, opening the debate regarding the cost-effectiveness of current screening/surveillance strategies. Thus, major efforts in clinical and research practice are focused on new methods for optimal risk assessment that can stratify BE patients at low or high risk of developing EAC, which should improve the cost effectiveness of screening/surveillance programs and consequently significantly affect health-care costs. Furthermore, the area of BE therapeutic management is rapidly evolving. Endoscopic eradication therapies have been shown to be effective, and new therapeutic options for BE and EAC have emerged. The aim of the present review article is to highlight the status of screening/surveillance programs and the current progress of BE therapy. Moreover, we discuss the recent introduction of novel esophageal pathophysiological exams that have improved the knowledge of the mechanisms linking GERD to BE.

Vigor of peristalsis during multiple rapid swallows is inversely correlated with acid exposure time in patients with NERD

BACKGROUND

Multiple rapid swallowing (MRS) during high-resolution manometry (HRM) is increasingly utilized as provocative test to assess esophageal peristaltic reserve. The aim of this study was to evaluate the correlation between MRS response and impedance and pH (MII-pH) parameters in endoscopy negative heartburn (ENH) patients.

METHODS

We enrolled consecutive ENH patients, who underwent HRM and MII-pH study, with a selected MII-pH profile: abnormal MII-pH (pH+/MII+); normal MII-pH (pH-/MII-). HRM was performed with 10 wet swallows (WS) and one MRS. Mean distal contractile integral (DCI) during WS and MRS were calculated. MII-pH parameters including acid exposure time (AET), reflux events, baseline impedance levels (BI) and the efficacy of chemical clearance evaluated with the postreflux swallow-induced peristaltic wave (PSPW) index were measured.

KEY RESULTS

We analyzed 103 patients: 49 MII+/pH+ (27 male), and 54 MII-/pH- (19 male). Mean age was similar between the two groups. As expected, mean AET and number of refluxes were higher in pH+/MII+ (p < 0.05). HRM was normal in all selected patients. Mean DCI-WS was similar between two groups (p = n.s.). Mean DCI-MRS- was higher in MII-/pH- vs MII+/pH+ (p < 0.05). The increase in DCI-MRS was inversely correlated with AET (-0.699; p < 0.001) and directly correlated with BI values (0.631; p < 0.001) and PSPW index (0.626; p < 0.001).

CONCLUSIONS & INFERENCES

Following MRS, patients with abnormal impedance-pH test showed suboptimal contraction response as compared with those with normal impedance-pH test. Moreover, MRS response was inversely correlated with AET and directly correlated with BI values and PSPW index.