Comparison of esophageal acid exposure at 1 cm and 6 cm above the squamocolumnar junction using the Bravo pH monitoring system

Mechanisms and pathophysiology of Barrett oesophagus

Barrett oesophagus, in which a metaplastic columnar mucosa that can predispose individuals to cancer development lines a portion of the distal oesophagus, is the only known precursor of oesophageal adenocarcinoma, the incidence of which has increased profoundly over the past several decades. Most evidence suggests that Barrett oesophagus develops from progenitor cells at the oesophagogastric junction that proliferate and undergo epithelial-mesenchymal transition as part of a wound-healing process that replaces oesophageal squamous epithelium damaged by gastroesophageal reflux disease (GERD). GERD also seems to induce reprogramming of key transcription factors in the progenitor cells, resulting in the development of the specialized intestinal metaplasia that is characteristic of Barrett oesophagus, probably through an intermediate step of metaplasia to cardiac mucosa. Genome-wide association studies suggest that patients with GERD who develop Barrett oesophagus might have an inherited predisposition to oesophageal metaplasia and that there is a shared genetic susceptibility to Barrett oesophagus and to several of its risk factors (such as GERD, obesity and cigarette smoking). In this Review, we discuss the mechanisms, pathophysiology, genetic predisposition and cells of origin of Barrett oesophagus, and opine on the clinical implications and future research directions.

Narrow-band imaging for the diagnosis of nonerosive reflux disease: an international, multicenter, randomized controlled trial

BACKGROUND AND AIMS

We examined the accuracy of narrow-band imaging (NBI) findings in nonerosive reflux disease (NERD) patients compared with control subjects and the impact of proton pump inhibitor (PPI) therapy on these mucosal changes in a multicenter, double-blind, randomized controlled trial.

METHODS

NERD patients (typical symptoms using a validated GERD questionnaire, absence of erosive esophagitis, and abnormal 48-hour pH study) and control subjects underwent high-definition white-light endoscopy followed by NBI and biopsy sampling of the distal esophagus. Then, NERD patients were randomized to esomeprazole 40 mg/day or placebo for 8 weeks, followed by repeat endoscopy. The presence of distal esophageal mucosal changes on NBI were recorded at baseline and after treatment: intrapapillary capillary loops (IPCLs; number, dilation, and tortuosity), microerosions, increased vascularity, columnar islands, and ridge/villous pattern (RVP) above the squamocolumnar junction.

RESULTS

Of 122 screened, 21 NERD and 21 control subjects were identified (mean age, 49.5 ± 14.6 years; 62% men; and 85% white). The combination of IPCL tortuosity, RVP, and microerosions (62% vs 19%, P < .05) had a high specificity (86%) and moderate sensitivity (60%) for NERD with an area under the curve of .74. In 10 NERD patients treated with PPIs, resolution of microerosions was most significant (P = .047) compared with placebo (n = 11). RVP resolved in all NERD patients after therapy (P = .02) and correlated with acid exposure time (P = .004). Papillary length (P = .02) and basal cell thickness (P = .02) significantly correlated with a combination of IPCL tortuosity, RVP, and microerosions.

CONCLUSIONS

In this randomized controlled trial, RVP on NBI demonstrated a high specificity, correlated with acid exposure time, and improved with PPI therapy, suggesting that it could be used as a surrogate marker for diagnosis of NERD. (Clinical trial registration number: NCT02081404.).

Kyoto international consensus report on anatomy, pathophysiology and clinical significance of the gastro-oesophageal junction

OBJECTIVE

An international meeting was organised to develop consensus on (1) the landmarks to define the gastro-oesophageal junction (GOJ), (2) the occurrence and pathophysiological significance of the cardiac gland, (3) the definition of the gastro-oesophageal junctional zone (GOJZ) and (4) the causes of inflammation, metaplasia and neoplasia occurring in the GOJZ.

DESIGN

Clinical questions relevant to the afore-mentioned major issues were drafted for which expert panels formulated relevant statements and textural explanations.A Delphi method using an anonymous system was employed to develop the consensus, the level of which was predefined as ≥80% of agreement. Two rounds of voting and amendments were completed before the meeting at which clinical questions and consensus were finalised.

RESULTS

Twenty eight clinical questions and statements were finalised after extensive amendments. Critical consensus was achieved: (1) definition for the GOJ, (2) definition of the GOJZ spanning 1 cm proximal and distal to the GOJ as defined by the end of palisade vessels was accepted based on the anatomical distribution of cardiac type gland, (3) chemical and bacterial (Helicobacter pylori) factors as the primary causes of inflammation, metaplasia and neoplasia occurring in the GOJZ, (4) a new definition of Barrett's oesophagus (BO).

CONCLUSIONS

This international consensus on the new definitions of BO, GOJ and the GOJZ will be instrumental in future studies aiming to resolve many issues on this important anatomic area and hopefully will lead to better classification and management of the diseases surrounding the GOJ.

Safety and Efficacy of Wireless pH Monitoring in Patients Suspected of Gastroesophageal Reflux Disease: A Systematic Review

INTRODUCTION

The primary aim of this systematic review was to determine the safety, technical efficacy, and effectiveness of 48-hour wireless pH monitoring (WM) for gastroesophageal reflux disease (GERD), compared with no pH monitoring in patients who failed to tolerate a catheter. In the absence of eligible studies, the secondary aim was to determine these performance characteristics for WM relative to catheter-based pH monitoring (CBM) in patients suspected of GERD, who are able to tolerate a catheter.

METHODS

A protocol was registered on the PROSPERO database (CRD42013005852) before conducting the systematic review, which included the study selection criteria, and critical appraisal methods. Several key databases were searched to identify eligible comparative studies.

RESULTS

Chest pain occurred more often with WM compared with CBM; however, other adverse events were reported less frequently with WM. Technical failures, mostly due to attachment failures and early capsule detachments, were 3 times higher with WM, compared with CBM, [pooled relative risk (from meta-analysis)=3.3; 95% confidence interval, 1.63-6.81; I=0%; P=0.012; k=8). The sensitivity and specificity of WM varied widely, depending on type of analysis, monitoring time, capsule placement, reference standard, and diagnostic threshold.

DISCUSSION

WM is usually better tolerated than CBM but has more technical problems. Test accuracy was highly variable between studies; therefore, conclusions could not be drawn regarding the performance of the 2 tests. To make meaningful comparisons between WM and CBM a consensus is needed on the diagnostic threshold for GERD, monitoring time, appropriate capsule positioning, and the reference standard.

Accuracy of the Air Flow Sphincter Locator system in identifying the lower esophageal sphincter for placement of pH catheters

The Air Flow Sphincter Locator (AFSL) is marketed as an alternative method to manometry for localizing the lower esophageal sphincter (LES) for pH probe placement. Such a system is desirable due to the additional time, cost, and discomfort associated with dual nasal intubation, but its accuracy has never been assessed. To assess the accuracy of the AFSL in localizing the LES. Fifty consecutive outpatients presenting for pH and manometry studies were included. The upper border of the LES was determined using HRM and the AFSL by two technicians independently. LES locations measured by technicians using AFSL versus manometry, as well as the manometrically determined LES locations by technicians versus MDs were compared. Differences in LES locations determined by HRM as read by MDs versus technicians were small; none were >3 cm, and 92% were within 2 cm. Comparison between LES locations determined by technicians using HRM versus the AFSL revealed that 52% had a difference of 2-3cm and 32% had a difference of >3 cm. Hiatal hernia was associated with a difference in LES location of >3 cm. Excluding patients with hiatal hernia, nonetheless, still produced a >3 cm difference in 24% of studies. Prior reports have suggested that a difference greater than +/-3 cm in pH probe placement is considered unacceptable for clinical studies. Based on our study, the AFSL placed the LES outside of this range in 32% of patients, and may be particularly inaccurate in the setting of a hiatal hernia. This suggests that the device may not be an acceptable alternative to manometry in determining LES location for pH probe placement.

Acid and nonacid reflux monitoring

Detection of acid and nonacid reflux using esophageal reflux monitoring, which includes conventional and wireless pH monitoring and pH impedance, can be a valuable diagnostic tool when used appropriately in the assessment of patients with gastroesophageal reflux disease. Reflux monitoring may be especially helpful if a management change is desired, such as when initial or empirical treatment is ineffective. However, each of these methods has its limitations, which need to be accounted for in their clinical use. Indications, test performance, interpretation, and clinical applications of esophageal reflux monitoring, as well as their limitations, are discussed in this review.

The postprandial acid pocket does not extend into most distal esophagus: evidence from pH studies performed immediately above the squamocolumnar junction

OBJECTIVE

The postprandial acid pocket is suggested to be an important factor in the pathogenesis of gastroesophageal reflux disease (GERD) as it according to the theory extends into the distal esophagus. The aim of this study was to test the hypothesis that the acid pocket transverses the squamocolumnar junction (SCJ) and exposes the most distal esophagus to gastric acid for extended periods following a meal.

MATERIAL AND METHODS

Fifty asymptomatic volunteers and 75 patients with GERD underwent 48-h pH monitoring with the electrode of a pH capsule placed immediately above the SCJ. The characteristics of esophageal acid exposure from the 90-min postprandial periods were compared with those observed during the upright, preprandial periods.

RESULTS

In asymptomatic controls, the degree of postprandial esophageal acid exposure was similar to that observed in the preprandial periods (median % time with pH <4, 2.2 vs. 2.6, p = 0.165). In contrast, symptomatic patients had significantly greater acid exposure in the postprandial compared with the preprandial periods (median % time with pH <4, 15.5 vs. 8.5, p < 0.001). The higher degree of acid exposure during the postprandial periods was due to a significantly higher number of short reflux episodes and reflux events with long durations were infrequent.

CONCLUSION

Postprandial acid exposure in the most distal esophagus was characterized by numerous short reflux events, and reflux events of long durations were rare. Our observations suggest that the acid pocket is confined to the stomach, questioning the importance of the acid pocket in GERD.

Gastric acid pocket and gastroesophageal reflux disease

Gastric acid pocket is an area of highly acid that escapes the neutralization of food in the proximal stomach after meals and has been noticed in healthy individuals and gastroesophageal reflux disease (GERD) patients. It was first found by Fletcher et al, who carried out a series of experiments in 2001. After that, other researchers have carried out in-depth studies on it. Hiatus hernia, gastric motility, gastric anatomy and physiology seem to be important elements for the genesis of postprandial proximal gastric acid pocket (PPGAP). Because PPGAP may play an important role in the pathogenesis of GERD, treatments for suppressing the production of gastric acid, antacid agents, prokinetic agents, surgery and other treatments may be used to alter the presence of PPGAP to achieve the purpose of treating GERD. Therefore, the discovery of gastric acid pocket may provide a new idea for the treatment of GERD.

The acid pocket: a target for treatment in reflux disease?

The nadir esophageal pH of reflux observed during pH monitoring in the postprandial period is often more acidic than the concomitant intragastric pH. This paradox prompted the discovery of the "acid pocket", an area of unbuffered gastric acid that accumulates in the proximal stomach after meals and serves as the reservoir for acid reflux in healthy individuals and gastroesophageal reflux disease (GERD) patients. However, there are differentiating features between these populations in the size and position of the acid pocket, with GERD patients predisposed to upward migration of the proximal margin onto the esophageal mucosa, particularly when supine. This upward migration of acid, sometimes referred to as an "acid film", likely contributes to mucosal pathology in the region of the squamocolumnar junction. Furthermore, movement of the acid pocket itself to a supradiaphragmatic location with hiatus hernia increases the propensity for acid reflux by all conventional mechanisms. Consequently, the acid pocket is an attractive target for GERD therapy. It may be targeted in a global way with proton pump inhibitors that attenuate acid pocket development, or with alginate/antacid combinations that colocalize with the acid pocket and displace it distally, thereby demonstrating the potential for selective targeting of the acid pocket in GERD.

Observations of Acid Reflux and Motor Function in Distal Esophagus Using Simultaneous Measurements of Intra-esophageal pH and Pressure in 8 Directions With Novel Sensor Catheter - A Feasibility Study

Background/Aims

Esophagogastric junctional lesions, such as mucosal breaks with Los Angeles grade A or B reflux esophagitis, lacerations in Mallory Weiss syndrome, and short segment Barrett's esophagus, are mainly found in the right anterior wall of the distal esophagus. Asymmetrical lower esophageal sphincter pressure and resting radial asymmetrical acid reflux may be causes of this asymmetrical distribution of reflux esophagitis and short segment Barrett's esophagus. We developed a novel pH and pressure catheter to investigate the asymmetrical distributions of pH and intra-esophageal pressure in the distal esophagus.

Methods

One healthy male volunteer was enrolled in this study. Acid reflux and motor function in distal esophagus was investigated using simultaneous measurements of intra-esophageal pH and pressure in 8 directions with novel sensor catheter.

Results

Thirty-six acid and weak acid reflux events were observed, of which 22 were circumferential refluxes with pH drops in all channels and 14 were partial refluxes with pH drops in some channels. Increase in transient circumferential intraesophageal pressure was observed just after 72.7% of the circumferential reflux and 42.9% of the partial reflux events.

Conclusions

Using a novel sensor catheter, 2 different types of acid reflux events were identified in the present study.

Impact of prolonged 48-h wireless capsule esophageal pH monitoring on diagnosis of gastroesophageal reflux disease and evaluation of the relationship between symptoms and reflux episodes

CONTEXT

Gastroesophageal reflux disease is one of the most common digestive diseases and an important cause of distress to patients. Diagnosis of this condition can require ambulatory pH monitoring.

OBJECTIVES

To determine the diagnostic yield of a wireless ambulatory pH monitoring system of 48-hours, recording to diagnose daily variability of abnormal esophageal acid exposure and its symptom association.

METHODS

A total of 100 consecutive patients with persistent reflux symptoms underwent wireless pH capsule placement from 2004 to 2009. The wireless pH capsule was deployed 5 cm proximal to the squamocolumnar junction after lower esophageal sphincter was manometrically determined. The pH recordings over 48-h were obtained after uploading data to a computer from the receiver that recorded pH signals from the wireless pH capsule. The following parameters were analyzed: (1) percentual time of distal esophageal acid exposure; (2) symptom association probability related to acid reflux. The results between the first and the second day were compared, and the diagnostic yield reached when the second day monitoring was included.

RESULTS

Successful pH data over 48-h was obtained in 95% of patients. Nearly one quarter of patients experienced symptoms ranging from a foreign body sensation to chest pain. Forty-eight hours pH data analysis was statistically significant when compared to isolated analysis of day 1 and day 2. Study on day 2 identified seven patients (30.4%) that would be missed if only day 1 was analyzed. Three patients (18.7%) out of 16 patients with normal esophageal acid exposure on both days, showed positive symptom association probability, which generated an increase in diagnostic yield of 43.4%.

CONCLUSION

Esophageal pH monitoring with wireless capsule is safe, well tolerated, does not require sedation. The extended 48-h period of study poses an increased yield to diagnose gastroesophageal reflux disease patients.

Use of multiple channel pH monitoring for evaluation of ultra-distal reflux in patients after fundoplication for treatment of Barrett's esophagus

Dysplasia and esophageal adenocarcinoma may arise in patients with Barrett's esophagus after fundoplication esophageal pH monitoring showing no acid in esophagus. This suggests the need to develop methodology to evaluate the occurrence of ultra-distal reflux (1cm above the LES). The objective of the study was to compare acid exposition in three different levels: 5cm above the upper border of the LES, 1cm above the LES and in the intrasphincteric region. Eleven patients with Barrett's esophagus after Nissen fundoplication with no clinical, endoscopic and radiologic evidence of reflux were selected. Four-channel pH monitoring took place: channel A, 5cm above the upper border of the LES; channel B, 1cm above the LES; channel C, intrasphincteric; channel D, intragastric. The results of channels A, B and C were compared. There was significant increase in number of reflux episodes and a higher fraction of time with pH <4.0 in channel B compared to channel A. There was significant decrease in fraction of time with pH <4.0 in channel B compared to channel C. Two cases of esophageal adenocarcinoma were diagnosed in the studied patients. The region 1cm above the upper border of the LES is more exposed to acid than the region 5cm above the upper border of the LES, although this exposure occurred in reduced levels. The region 1cm above the upper border of the LES is less exposed to acid than the intrasphincteric region.

Determination of pH turning point with pH mapping of the gastroesophageal junction: an alternative technique to orientate esophageal pH monitoring

Manometric location of the lower esophageal sphincter (LES) has been mandatory before esophageal pH monitoring, despite costs and discomfort related with esophageal manometry. The aims of the study were: (i) to map the pH of the gastroesophageal junction (GEJ) to determine a pH turning point (PTP) and its relation with LES; and (ii) to test the feasibility of this technique to orientate esophageal pH monitoring. We studied 310 adult patients who underwent esophageal manometry and pH monitoring off acid-suppressive therapy. GEJ pH mapping was carried out by step-pulling the pH sensor from 5 cm below to 5 cm above LES, and a PTP was determined when pH changed from below to above 4, in centimeters from the nostril. Thirty-six patients referred only for pH monitoring were studied with pH sensor placed at 5 cm above the PTP. Out of 310 patients, a PTP was found in 293 (94.5%): inside LES in 86.3%, into the stomach in 8.2% and in the esophageal body in 5.5% of patients. The median distance between PTP and place where pH sensor monitored reflux was 8 cm. Among 36 patients who performed pH monitoring without LES manometry, there was no gastric monitoring during reflux testing. In adult patients investigated off acid suppressive therapy, GEJ pH mapping with reflux monitoring 5 cm above the PTP can be an alternative technique to perform esophageal pH monitoring when LES manometry is not available. Additional studies are needed before the widespread use of GEJ pH mapping in the clinical practice.

Current applications of evolving methodologies in gastroesophageal reflux disease testing

Until recently catheter-based 24-h pH monitoring has been the primary methodology for the objective diagnosis of gastroesophageal reflux disease. Yet, this system has some drawbacks, such as patient discomfort, marginal sensitivity, and the inability to detect nonacid reflux. Hampered by these limitations, several new techniques have been recently introduced in clinical practice. In particular, wireless capsule pH monitoring and multichannel intraluminal impedance-pH testing have been forwarded as more sophisticated means of enhancing patient comfort during testing as well as our ability to diagnose gastroesophageal reflux disease, especially in those patients who complain of symptoms of gastroesophageal reflux disease despite adequate acid suppression therapy. The goal of this review is to compare the clinical applicability, advantages and drawbacks of catheter-based 24-h pH testing, wireless capsule pH monitoring, and multichannel intraluminal impedance-pH.

Impact of measurement of esophageal acid exposure close to the gastroesophageal junction on diagnostic accuracy and event-symptom correlation: a prospective study using wireless dual pH monitoring

OBJECTIVES

Ambulatory esophageal pH monitoring has limited diagnostic accuracy in patients with gastroesophageal reflux disease (GERD), especially in those with non-erosive reflux disease (NERD). In addition, there is lack of symptom-reflux association in the majority of GERD patients. The aim of this study was to evaluate the impact of measuring acid exposure 1 cm above the gastroesophageal junction (GEJ) on diagnostic accuracy and symptom correlation in GERD patients compared with conventional pH measurements (6 cm above the GEJ) using the wireless pH system.

METHODS

GERD patients and controls as defined by two validated questionnaires (Gastroesophageal Reflux Questionnaire and Reflux Disease Questionnaire) were prospectively enrolled. Under direct endoscopic vision, two wireless pH capsules (BRAVO, Given Imaging, Yokneam, Israel) were placed 6 and 1 cm, respectively, above the GEJ. Receiver operator characteristic curves were constructed, and symptom indexes were calculated separately for pH measurements at 6-cm (proximal) and 1-cm (distal) locations.

RESULTS

A total of 40 GERD patients (20 erosive esophagitis (EE) and 20 NERD) and 16 controls were analyzed. Sensitivity and specificity of abnormal acid exposure times in GERD were as follows: proximal: 67 and 66%, distal: 60 and 88%; in EE proximal: 75 and 81%, distal: 84 and 92%; and in NERD proximal: 61 and 67%, distal: 58 and 66%, respectively. The proportion of patients with a positive symptom-reflux correlation in GERD was as follows: symptom index (SI): proximal: 35%, distal: 50%; symptom sensitivity index (SSI): proximal: 25%, distal: 5%; and symptom-associated probability (SAP): proximal: 30% and distal: 35%. The higher proportion of patients with a positive SI distally was due to the EE group (EE, proximal: 35% and distal: 65%; NERD, proximal: 35% and distal: 35%).

CONCLUSIONS

Compared with the traditional location, measurement of acid reflux 1 cm above the GEJ improved the diagnostic accuracy as well as symptom correlation in EE, but not in NERD patients. Thus, pH monitoring 1 cm above the GEJ for improving the diagnosis of NERD cannot be recommended in clinical practice at this time.

The value of high-resolution manometry in the assessment of the resting characteristics of the lower esophageal sphincter

INTRODUCTION

High-resolution manometry (HRM) is faster and easier to perform than conventional water perfused manometry. There is general acceptance of its usefulness in evaluating upper esophageal sphincter and esophageal body. There has been less emphasis on the use of HRM to evaluate the lower esophageal sphincter (LES) resting pressure and length, both factors important in LES barrier function. The aim of this study was to compare the resting characteristics of the LES determined by HRM and conventional manometry in the same patients.

METHODS

We performed both HRM and conventional manometry including a slow motorized pull-through technique in 55 patients with foregut symptoms. The characteristics of the LES analyzed were: resting pressure, total length, and abdominal length. Four available modes of HRM analysis were used to assess resting characteristics of the LES: spatiotemporal mode using both abrupt color change and isobaric contour, line tracing, and pressure profile. The values obtained from these four HRM modes were then compared to the conventional manometry measurements.

RESULTS

High-resolution manometry and conventional manometry did not differ in their measurement of LES resting pressure. LES overall and abdominal length were consistently overestimated by HRM. A variability up to 4 cm in overall length was observed and was greatest in patients with hiatal hernia (1.8 vs. 0.9 cm, p = 0.027).

CONCLUSION

The current construction of the catheter and software analysis used in high-resolution manometry do not allow precise measurement of LES length. Errors in the identification of the upper border of the sphincter may compromise accurate positioning of a pH probe.

Comparison of the different characteristics of sensed reflux events among different heartburn groups

BACKGROUND AND AIM

Presently, there are no studies comparing sensed acid reflux event (SARE) characteristics among different heartburn groups. Our aim was to compare the different esophageal acid reflux characteristics of an SARE among the different heartburn groups.

METHODS

Patients with heartburn underwent endoscopy and pH testing and were stratified into 3 groups: erosive esophagitis (EE), nonerosive reflux disease (NERD), and functional heartburn (FH). Patients underwent esophageal pH testing using a 4-sensor pH probe, with the most distal pH sensor positioned 1 cm> lower esophageal sphincter (LES).

RESULTS

Twenty-two patients had EE, 15 NERD, and 13 FH (M/F: 20/2, 12/3, 5/8, mean age: 51.5+/-3.7, 50.1+/-4.2, 50.3+/-3.8, respectively). The percentage of SAREs at 1 cm>LES that had reached 16 cm>LES was significantly higher in the FH group compared with NERD and EE (P<0.05). EE demonstrated the lowest nadir during an SARE and NERD the most acid reflux events before an SARE (up to 4 h).

CONCLUSIONS

Patients with FH demonstrated the most SAREs that reached the proximal esophagus. EE patients demonstrated the lowest nadir pH during an SARE and NERD patients the most acid reflux events before an SARE, as compared with the other heartburn groups.

Utility of non-endoscopic investigations in the practical management of oesophageal disorders

The current available methods for diagnosis of GORD are symptom questionnaires, catheter and wireless pH-metry, impedance-pH monitoring and Bilitec(@). Osophageal pH monitoring allows both quantitative analysis of acid reflux and assessment of reflux-symptom association. Impedance-pH monitoring detects all types of reflux (acid and non-acid) and allows assessment of proximal extent of reflux, a relevant parameter for understanding symptoms perception and extraoesophageal symptoms. Bilitec provides a quantitative assessment of duodeno-gastro-oesophageal reflux. Oesophageal motor abnormalities have been associated with GORD symptoms as well as chest pain and dysphagia. High-resolution manometry contributed to re-classify oesphageal motor disorders. However, barium swallows are still essential for evaluation of oesophageal anatomy and combined oesophageal manometry-impedance can assess oesophageal motility and bolus transit simultaneously in a non-radiological way. Still in experimental phase, high-frequency ultrasound allows monitoring of the oesophageal wall thickness and exaggerated longitudinal muscle contraction that might be associated to chest pain and dysphagia. This chapter provides a critical evaluation of the clinical application of these techniques.

Comparison of wireless 48-h (Bravo) versus traditional ambulatory 24-h esophageal pH monitoring

OBJECTIVE

To compare wireless with catheter-based esophageal pH recordings.

MATERIAL AND METHODS

Forty-five patients with symptoms suggestive of gastroesophageal reflux disease and 47 healthy volunteers were investigated in a university-affiliated hospital; 48-h wireless esophageal pH recording was performed. During the first 24 h, simultaneous traditional pH recording by catheter was undertaken. Nine of the volunteers underwent repeated measurements with both techniques. Outcome measures were feasibility, agreement, concordance of diagnostic yield, reproducibility, and subjective symptoms.

RESULTS

Subjective parameters were less affected when using the wireless technique alone (p<0.05). On using the wireless technique, esophageal acid exposure was underestimated approximately by half compared with traditional recording (p<0.05). Although pH data obtained with the two techniques were correlated (r(2)=0.66, p<0.001), the range between limits of agreement was wide (-3.7 to 10.0 percentage units of total time pH <4). Coefficients of variation for repeated measurements were 60.1+/-26.3% for catheter recordings, and 66.0+/-47.3 for wireless recordings on day 1 (NS). Concordance of diagnostic yield was 81.5% with all subjects included.

CONCLUSIONS

Forty-eight-hour wireless Bravo pH monitoring is feasible but consistently underestimates esophageal acid exposure compared to the conventional technique. Although there is a significant correlation between the two techniques for pH recordings, the wide range in limits of agreement and the large coefficient of variation with both techniques suggest that the two methods are not immediately interchangeable for use in clinical practice.

Ambulatory monitoring of GERD: current technology

Various techniques have been devised to diagnose, characterize, and classify gastroesophageal reflux (GER). Stationary techniques, such as fluoroscopy and scintigraphy, provide interesting anatomic and functional information related to GER but are not sensitive enough and are usually performed in nonphysiologic conditions. Ambulatory techniques for GER monitoring have been developed and used since 1974. The current available techniques include catheter and wireless pH-metry, Bilitec, and impedance-pH monitoring. Prolonged wireless pH monitoring can be useful to evaluate patients off and on proton pump inhibitor (PPI) treatment. Impedance-pH monitoring is being used increasingly in patients who have persistent symptoms on PPI therapy because it can establish an association between symptoms and weakly acidic or nonacid reflux. Bilitec is performed in patients suspected to have increased duodenogastroesophageal reflux (DGER). This article discusses the technical details, clinical indications, and applications of these diagnostic techniques.

Wireless pH recording immediately above the squamocolumnar junction improves the diagnostic performance of esophageal pH studies

BACKGROUND AND AIMS

The optimal position for pH electrode placement in the diagnosis of gastroesophageal reflux disease (GERD) is unknown. The aim of this study was to evaluate the discriminatory power of targeted pH recording immediately above the squamocolumnar junction (SCJ) and to compare the results with those obtained by simultaneous recording at the conventional level for pH monitoring.

SUBJECTS AND METHODS

Sixty-two patients with typical reflux symptoms and 49 asymptomatic volunteers underwent 48-h simultaneous wireless pH monitoring with two endoscopically placed pH recording capsules, one immediately above the SCJ and one at the traditional position, 6 cm above the SCJ. The diagnostic accuracy, sensitivity, and specificity of pH monitoring at the two levels were analyzed using receiver operating characteristics (ROC) curves.

RESULTS

Of the 62 patients (39 men and 23 women, median age 48 yrs), 32 patients had erosive esophagitis and 30 had no endoscopic evidence of mucosal injury. Analysis of the area under the ROC curve (AUC) indicated that the total percent time with pH<4 for the entire 48-h period was the parameter that best distinguished GERD patients from controls. pH monitoring performed directly above the SCJ significantly increased the number of patients correctly classified with GERD compared to standard electrode placement. With a predefined test specificity of 90%, pH monitoring immediately above the SCJ increased the sensitivity of the test from 63% to 86% in all patients, from 78% to 97% in patients with esophagitis and from 47% to 73% in patients with no esophagitis.

CONCLUSIONS

Compared to standard electrode placement, wireless pH recording immediately above the SCJ improved the diagnostic performance of esophageal pH monitoring in patients with GERD.

Transoral endoscopic fundoplication in the treatment of gastroesophageal reflux disease: the anatomic and physiologic basis for reconstruction of the esophagogastric junction using a novel device

OBJECTIVE

To determine the safety, mechanism of action, immediate postprocedural anatomic impact on the esophagogastric junction, and short-term efficacy of the first entirely endolumenal antireflux procedure.

BACKGROUND

A safe and effective endoscopic antireflux procedure remains elusive. Transoral endolumenal surgery has enormous potential for the treatment of gastroesophageal reflux disease (GERD) and other esophagogastric diseases. A canine model was used to study a novel endoscopic device, which allows for creation of an endoluminal fundoplication.

METHODS

The transoral incisionless fundoplication (TIF) was performed in 21 canines in a phase I feasibility and safety study, and in 21 canines in a phase II study that included a detailed objective assessment of the effects of 2 variants of the TIF procedure (TIF 1.0 and TIF 2.0) versus sham on esophageal physiology and esophagogastric junction (EGJ) anatomy.

RESULTS

In phase I, TIF provided a safe and feasible endolumenal therapy for GERD, with histologic data that demonstrated serosal fusion of approximated full-thickness tissue plications and durability of the fundoplication. TIF procedures effectively reduced cardia circumference and improved Hill classification grade. In phase II, the TIF 2.0 procedure achieved normalization of distal esophageal acid exposure and increased lower esophageal sphincter (LES) pressure and length based on objective testing over a 2-week period. TIF 2.0 demonstrated superior results to TIF 1.0, and valve appearance and location exhibited similarity to the Nissen fundoplication by vector volume analysis.

CONCLUSIONS

The TIF procedure is safe and results in a durable and functional fundoplication as well as a platform for further development and modification of the procedure, which can be use to impact outcome. This work provides the foundation for human translation and assessment of long-term outcomes.

Transsphincteric pH profile at the gastroesophageal junction

BACKGROUND & AIMS

Esophageal acid exposure conventionally is measured 5 cm above the lower esophageal sphincter (LES). The aim of this study was to compare pH profiles at sites within the LES, the distal esophagus, and the proximal stomach.

METHODS

Ten normal subjects underwent esophageal manometry followed by 24-hour esophagogastric pH monitoring using an 8-channel pH probe recording at 5 and 1.5 cm above and at 0, 1.5, 3.0, 4.5, 6.0, and 9.5 cm below the proximal LES border. During pH recording, a 4-hour gastric emptying test with an egg sandwich meal was performed.

RESULTS

The LES was 3.2 +/- 0.4 cm in length. There was a progressive increase in acid exposure from the esophageal to the gastric pH sensors. pH was less than 4 for 3.4% +/- 1.6%, 12.7% +/- 8.5%, 26.5% +/- 10.2%, 48.1% +/- 11.3%, 66.5% +/- 9.9%, 80.8% +/- 5.6%, 89.2% +/- 3.0%, and 96.7% +/- 1.1% of the total time for pH probes at 5 and 1.5 cm above and 0, 1.5, 3, 4.5, 6.0, and 9.5 cm below the proximal LES border, respectively. Percentage acid exposures correlated significantly with the position of the probe (r = -0.95; P < .01). Intrasphincteric acidity increased postprandially. Gastric emptying was correlated inversely with the intragastric hydrogen ion concentration (r = -0.82).

CONCLUSIONS

The percentage of recording time that pH was less than 4 was significantly higher in the intrasphincteric area and 1.5 cm above the proximal LES compared with the traditional site 5 cm above the proximal manometric LES border. High acid exposure in the intrasphincteric region might explain the susceptibility of the distal esophagus to erosions, strictures, and Barrett's esophagus.

Acidity surrounding the squamocolumnar junction in GERD patients: "acid pocket" versus "acid film"

AIM

This study aimed to localize the gastric-to-esophageal pH transition point relative to the squamocolumnar junction (SCJ) and esophagogastric junction (EGJ) high-pressure zone in controls and GERD patients.

METHODS

Ten controls and 10 GERD patients were studied. Subjects had an endoclip placed at the SCJ prior to a pH catheter pull-through (upright and supine) during concurrent fluoroscopy before and after consuming a standardized meal. Six controls and 6 GERD patients also underwent concurrent manometry. The relative positions of the SCJ, EGJ high-pressure zone, and pH transition points were analyzed.

RESULTS

Most controls and GERD patients exhibited an unbuffered acidified segment in the proximal stomach postprandially. The proximal pH transition point was confined distal to the SCJ in control subjects, regardless of posture or meal state. GERD patients exhibited a more proximal pH transition point, extending above the SCJ and EGJ high-pressure zone in the supine position, especially postprandially. However, the high-pressure zone was intact.

CONCLUSION

A short segment of unbuffered acidity of unknown volume exists after meals in the proximal stomach. In controls, the unbuffered acidic segment is contained distal to the SCJ while in the GERD patients it extended into and even across the EGJ high-pressure zone. However, this extension through the EGJ in GERD patients occurred in the context of an intact sphincter suggesting that this is best conceptualized as an acid "film" rather than a "pocket." This observation may help explain the propensity of the distal esophageal mucosa to lesions of reflux disease.

Developments in pathogenesis and diagnosis of gastroesophageal reflux disease

PURPOSE OF REVIEW

Although gastroesophageal reflux is a common disorder, diagnosis is still imprecise. Moreover, its pathogenesis is incompletely understood. This review summarizes recent progress in diagnosis and our understanding of the pathogenesis of gastroesophageal reflux disease.

RECENT FINDINGS

Recent studies have focused on the pattern of reflux in the distal esophagus, just above the esophago-gastric junction, challenging its importance on the genesis of reflux symptoms. New techniques, such as impedance, could improve the diagnostic yield, especially in patients with nonacid reflux. Esophageal sensitivity and motility, transient lower esophageal sphincter relaxations, and hiatus hernia are important pathogenic mechanisms of reflux disease. Studies showed that obesity plays a role in the pathogenesis of reflux symptoms; a disruption of the esophago-gastric junction (leading to hiatus hernia) could allow reflux to occur. The association between reflux (particularly nonacid) and extraesophageal manifestations of gastroesophageal reflux disease has been further evaluated.

SUMMARY

Improvement of diagnostic techniques and better understanding of the pathogenesis of reflux may lead to new or better therapeutic modalities. Our understanding of some of the risk factors for reflux has been increased. Extra-esophageal manifestations and their association with gastroesophageal reflux are still a very controversial and promising area of research.

ACG practice guidelines: esophageal reflux testing

Investigations and technical advances have enhanced our understanding and management of gastroesophageal reflux disease. The recognition of the prevalence and importance of patients with endoscopy-negative reflux disease as well as those refractory to proton pump inhibitor therapy have led to an increasing need for objective tests of esophageal reflux. Guidelines for esophageal reflux testing are developed under the auspices of the American College of Gastroenterology and its Practice Parameters Committee and approved by the Board of Trustees. Issues regarding the utilization of conventional, catheter-based pH monitoring are discussed. Improvements in the interpretation of esophageal pH recordings through the use of symptom-reflux association analyses as well as limitations gleaned from recent studies are reviewed. The clinical utility of pH recordings in the proximal esophagus and stomach is examined. Newly introduced techniques of duodenogastroesophageal reflux, wireless pH capsule monitoring and esophageal impedance testing are assessed and put into the context of traditional methodology. Finally, recommendations on the clinical applications of esophageal reflux testing are presented.