Conventional pH Monitoring Research Articles

Public Health Security Systems Empowered by Artificial Intelligence for Early Monitoring and Prevention of Epidemics

Artificial intelligence (AI) methods have been extensively used for detecting and predicting Infectious Disease (ID) outbreaks as time series and modeling and evaluating Public Health responses. The significant tasks of PH monitoring and intervention present distinct technical difficulties, including limited data availability, absence of sufficient positive training examples, challenges in establishing benchmarks, measuring the effectiveness of management policies, complex relationships between spatial and time series elements, and more detailed risk assessments involving interaction and social networks. Conventional PH monitoring mainly depends on statistical methods. In recent years, there has been a significant expansion of approaches that AI enables. This research presents an AI method called Early Monitoring and Prevention of Epidemics (AI-EMPE) for enhancing PH security systems. The suggested approach converts a substantial amount of collected PH security incidents into separate incident characteristics and utilizes a Deep Learning (DL)--based detection technique to enhance EMPE. AI-EMPE incorporates sophisticated AI methods, including integrated Convolutional Neural Networks (CNN) and Backpropagation Neural Networks (BP-NN). These findings indicate that the integrated method is the most efficient in improving PH security systems.

Simultaneous laryngopharyngeal pH monitoring (Restech) and conventional esophageal pH monitoring-correlation using a large patient cohort of more than 100 patients with suspected gastroesophageal reflux disease.

24-hour esophageal pH-metry is not designed to detect laryngopharyngeal reflux (LPR). The new laryngopharyngeal pH-monitoring system (Restech) may detect LPR better. There is no established correlation between these two techniques as only small case series exist. The aim of this study is to examine the correlation between the two techniques with a large patient cohort. All patients received a complete diagnostic workup for gastroesophageal reflux including symptom evaluation, endoscopy, 24-hour pH-metry, high resolution manometry, and Restech. Consecutive patients with suspected gastroesophageal reflux and disease-related extra-esophageal symptoms were evaluated using 24-hour laryngopharyngeal and concomitant esophageal pH-monitoring. Subsequently, the relationship between the two techniques was evaluated subdividing the different reflux scenarios into four groups. A total of 101 patients from December 2013 to February 2017 were included. All patients presented extra-esophageal symptoms such as cough, hoarseness, asthma symptoms, and globus sensation. Classical reflux symptoms such as heartburn (71%), regurgitation (60%), retrosternal pain (54%), and dysphagia (32%) were also present. Esophageal 24-hour pH-metry was positive in 66 patients (65%) with a mean DeMeester Score of 66.7 [15-292]. Four different reflux scenarios were detected (group A-D): in 39% of patients with abnormal esophageal pH-metry, Restech evaluation was normal (group A, n=26, mean DeMeester-score=57.9 [15-255], mean Ryan score=2.6 [2-8]). In 23% of patients with normal pH-metry (n=8, group B), Restech evaluation was abnormal (mean DeMeester-score 10.5 [5-13], mean Ryan score 63.5 [27-84]). The remaining groups C and D showed corresponding results. Restech evaluation was positive in 48% of cases in this highly selective patient cohort. As demonstrated by four reflux scenarios, esophageal pH-metry and Restech do not necessarily need to correspond. Especially in patients with borderline abnormal 24-hour pH-metry, Restech may help to support the decision for or against laparoscopic anti-reflux surgery.

Hypopharyngeal multichannel intraluminal impedance leads to the promising outcome of antireflux surgery in Japanese population with laryngopharyngeal reflux symptoms.

Clinical characteristics of laryngopharyngeal reflux (LPR) in Japanese population remain unclear, and its treatment outcome is suboptimal. The objectives of this study were to evaluate Japanese patients with LPR symptoms using hypopharyngeal multichannel intraluminal impedance (HMII) and to assess the outcome of antireflux surgery (ARS). Subjects included patients who had LPR symptoms for > 12 weeks or laryngoscopic findings suggestive of LPR and underwent laryngoscopy and esophageal testing including HMII. Abnormal proximal exposure (APE) was defined as LPR ≥ 1/day and/or full column reflux (FCR) (reflux 2cm distal to the upper esophageal sphincter) ≥ 5/day on HMII. Patients with APE were offered ARS and the outcome of ARS was objectively assessed using Reflux Symptom Index (RSI). From July 2015 to September 2016, 52 patients with LPR symptoms (28 men, 24 women, median BMI 22.3) underwent HMII, and 38 patients (73%) had APE. Of them, 29 (76%) patients were not obese (BMI < 25) and 19 (50%) patients had a negative DeMeester score. Approximately one-third of LPR and FCR events were non-acid in the distal esophagus. A positive symptom-association probability was seen only in 18 patients (35%). Mild esophagitis and hiatal hernia were found in 5 (10%) and 23 (48%) patients, respectively. All 12 patients (100%) who had undergone ARS were able to discontinue PPI and had a significant improvement in the RSI scores postoperatively (22.9 ± 10.0 vs. 6.8 ± 6.8, p <.001). APE was frequently observed in Japanese patients with LPR symptoms. Obesity and esophagitis were uncommon in this population. Since a large number of patients with APE had negative DeMeester score and proximal reflux events were often non-acid, a conventional pH monitoring is insufficient. HMII is crucial to evaluate patients with LPR symptoms as the documentation of APE is a key for successful outcome of ARS.

PTU-126 High Incidence of Oesophageal Dysmotility and Increased Inspiratory Gastro-Oesophageal Pressure Gradients in Patients with Unexplained Respiratory Symptoms

Introduction It has been suggested that reflux and aspiration are common precipitants in respiratory diseases such as cough, asthma and Chronic Obstructive Pulmonary Disease. An excess of acid in these patients has been demonstrated by conventional pH monitoring, but correlation with symptoms are relatively poor. We have previously hypothesised that oesophageal dysmotility leading to both acid and non-acid aspiration may be an important etiological mechanism. Studies have also highlighted the importance of the gastro-oesophageal pressure gradient (GOPG) in the prevalence of reflux. 1 Methods High Resolution Oesophageal Manometry (HRM) was performed in 121 patients, 61 of whom presented primarily with unexplained respiratory symptom and complained predominantly of chronic cough (50), or breathlessness (11). An age and sex matched control group was chosen from patients presenting with suspected gastro-oesophageal reflux disease (GORD). The HRM findings of 61 patients (38 female), mean age 56 (range 18–81) with respiratory symptoms were compared with those of 60 suspected GORD patients (39 female), mean age 57, (range 19–81). Results Mean lower oesophageal sphincter (LOS) and upper oesophageal sphincter (UOS) resting pressures were similar between the two groups. There were fewer intact swallows in the respiratory group compared to those of the GORD group (42% vs 57%, P = 0.03). Intraoesophageal pressure was significantly lower during inspiration in the respiratory group compared to those of the GORD group (-11.5mmHg vs -8.7, p = 0.001). Consequently, there was a significantly higher GOPG was found in respiratory patients compared to those of the GORD group (46 mmHg vs 33 mmHg, p Conclusion Using High Resolution Oesophageal Manometry, we have demonstrated a higher prevalence of oesophageal dysmotility in patients with unexplained respiratory symptoms than those presenting with typical GORD. Moreover, we have shown that those with unexplained respiratory symptoms exhibit higher inspiratory GOPGs and greater LOS peak contractions possibly stimulating an afferent vagal cough response. Reference 1 Ayazi S, DeMeester SR, et al . Thoracic-abdominal pressure gradients during the phases of respiration contribute to gastroesophageal reflux disease. Digestive Disease and Sciences 2011; 56 :1718–22. Disclosure of Interest None Declared

Is the Routine Use of Impedance Analysis for the Diagnosis of Gastro-Esophageal Reflux Disease More Expensive than Conventional pH Monitoring? Cost Analysis of Two Procedures.

Conventional 24-h pH monitoring is the gold standard for the diagnosis of non-erosive, non-acidic gastro-esophageal reflux disease. Multichannel Intraluminal Impedance (MII) analysis markedly improves diagnostic accuracy of non-erosive, non-acidic gastro-esophageal reflux disease. However, MII catheters are more expensive than standard catheters. This study aimed to determine the rates of acid or non-acid reflux and by making a retrospective projection, to predict the costs of two algorithms. We retrospectively reviewed the medical data of 102 patients who presented to our hospital with suspected non-erosive GERD and underwent 24h impedance/pH-monitoring. Demographic characteristics, Demeester scores, number of reflux episodes, and results of impedance analysis were recorded. According to these data, cost was calculated either for the scenario in which impedance measurement was performed solely or following a negative conventional pH monitoring. Thirty-seven of all 102 patients (36.3%) had a Demeester score greater than 14.7. These patients were assigned as group 1 (acid reflux). The impedance analysis of the remaining 65 patients detected 34 patients (33.3%) to have more than 50 reflux episodes over a period of 24h and assigned as Group 2, and 31 patients (30.4%) had no reflux (group 3). The cost of the single- step algorithm using MII catheter was calculated as $15,300, while the total cost of two-step scenario would have been predicted as $16,890. Our study showed that an initial conventional pH monitoring can make the diagnosis of GERD in only one third of the patients with suspected non-erosive GERD. In nearly two-thirds of patients, however, repeated procedures and use of impedance catheters are needed. It is clear that this algorithm has certain drawbacks with regard to cost, patient comfort, and workforce loss.

The feasibility and efficacy of multi-channel intraluminal impedance monitoring in children.

The diagnosis of gastro-oesophageal reflux is currently based on clinical presentation and oesophageal pH monitoring. In recent years, the use of multi-channel intraluminal impedance (MII) monitoring has gained increasing attention in the adult population. However, its use in the paediatric population is still in the developing stage with only limited number of publications. This study aims to review our early experience of MII application in children. A retrospective study of all patients who underwent MII monitoring between 2011 and 2014 at a tertiary referral centre was performed. Patients' medical records were reviewed with demographic data extracted. Number of reflux episodes and other MII parameters were analysed. In total, 34 patients were identified during the study period, with 20 males and 14 females. Indication for study included previous aspiration pneumonia (n=13), persistent reflux or vomiting symptom (n=10) and as part of routine assessment before gastrostomy (n=11). At the time of study the average age was 69months (range 9-216months). 28 patients showed significant gastro-oesophageal reflux. On average patient has 36.1 acidic and 22.3 non-acidic reflux episodes during the 24h monitoring period. Non-acidic reflux accounts for 38.1% of the overall reflux episodes. The sensitivity of MII monitoring to detect reflux was higher compared to conventional pH study (73 vs 50%, p=0.1). MII monitoring is safe and feasible in children. Non-acid reflux should not be underestimated in paediatric population. MII appears to be more sensitive than conventional pH monitoring in our study, but its true significance is yet to be confirmed by larger study in the future.

G366(P) Impedance monitoring in paediatric gastro-oesophageal reflux disease: an evaluation of its use and clinical value

We sought to evaluate the use of combined oesophageal multichannel intraluminal impedance and pH (MII-pH) monitoring in the Paediatric department of a large tertiary hospital, and to determine whether there is added value of MII-pH monitoring beyond that of conventional pH monitoring. We conducted a retrospective study of all paediatric patients who underwent MII-pH monitoring during a two year period (01/01/2012–31/12/2013) in a large tertiary hospital. We analysed the demographics, indications for investigation and MII-pH results for each patient. We assessed the effect of anti-reflux treatment on MII-pH results and compared the relative contribution of MII data with pH data in each test. 96 studies were performed on 96 patients (mean age 3 years 8 months, range 2 months to 16 years, 55 male, 41 female). 57 studies produced interpretable results of greater than 20 h’ duration. Respiratory symptoms were the most common indication for study. Patients who had taken anti-reflux medication at any point in the week prior to the study were significantly less likely to have an abnormal reflux index (RI; p This study provides a comprehensive review of the use of MII-pH monitoring in a large tertiary centre. It reinforces previous literature findings that anti-reflux medication reduces oesophageal acid exposure, but does not necessarily reduce total reflux frequency or symptom correlation. The value added by MII-pH monitoring beyond that of conventional pH monitoring remains to be established. The results here support the use of RI (derived from pH monitoring) as an indicator for reflux disease in patients off treatment.

Implementation of objective activity monitoring to supplement the interpretation of ambulatory esophageal PH investigations

Conventional catheter-based systems used for ambulatory esophageal pH monitoring have been reported to affect patient behavior. As physical activity has been associated with gastroesophageal reflux disease (GERD), there is a risk that abnormal behavior will degrade the value of this diagnostic investigation and consequent management strategies. The aim of this study was to quantify the effect of conventional pH monitoring on behavior and to investigate the temporal association between activity and reflux. A total of 20 patients listed for 24 hours pH monitoring underwent activity monitoring using a lightweight ear-worn accelerometer (e-AR sensor, Imperial College London) 2 days prior to, and during their investigation. PH was measured and recorded using a conventional nasogastric catheter and waist-worn receiver. Daily activity levels, including subject-specific activity intensity quartiles, were calculated and compared. Physical activity was added to the standard pH output to supplement interpretation. Average patient activity levels decreased by 26.5% during pH monitoring (range -4.5 to 51.0%, P = 0.036). High-intensity activity decreased by 24.4% (range -4.0 to 75.6%, P = 0.036), and restful activity increased on average by 34% although this failed to reach statistical significance (-24.0 to 289.2%, P = 0.161). Some patients exhibited consistent associations between bouts of activity and acidic episodes. The results of this study support the previously reported reduction in activity during ambulatory esophageal pH monitoring, with the added reliability of objective data. In the absence of more pervasive pH monitoring systems (e.g. wireless), quantifying activity changes in the setting of activity-induced reflux might guide the physicians' interpretation of patient DeMeester scores resulting in more appropriate management of GERD.

Impedance-pH monitoring and conventional pH monitoring are complementary methods to detect association between gastroesophageal reflux and apnea-related symptoms in preterm infants and neonates

Objective: To investigate the usefulness of Multichannel intraluminal impedance-pH (MII-pH) monitoring as compared with conventional pH monitoring for detecting Gastroesophageal reflux (GER) episodes and apnea-related symptom association in preterm infants and neonates. Methods: Twenty-three infants (16 preterm and 7 term infants) in hospital, who underwent 24-h MII-pH monitoring, were studied retrospectively. GER indices and apnea-related symptom association were measured by both MII-pH and conventional pH based analysis. Results: Of the total 998 GER episodes assessed by MII-pH monitoring, 407 (40.8%) were acidic and 590 (59.1%) were weakly acidic. A total of 1689 GER episodes were detected by conventional pH based analysis and 270 (16%) were related to retrograde bolus movement. A total of 313 apnea-related symptoms were reported. Five patients had a positive symptom association: 3 by MII-pH, 1 by both MII-pH and conventional pH, 1 only by conventional pH. Conclusions: Addition of MII-pH monitoring to conventional pH monitoring improves the diagnostic yield of symptom association analysis in preterm infants and neonates with apnea-related symptoms. Conventional pH monitoring is still important in the era of impedance measurement.

Pathogenesis of proton‐pump inhibitor‐refractory non‐erosive reflux disease according to multichannel intraluminal impedance‐pH monitoring

Proton-pump inhibitor (PPI) therapy is the first-line treatment for gastroesophageal reflux disease; however, there are some reports of PPI failure in cases of non-erosive reflux disease (NERD). Among the pathogenic factors associated with PPI-refractory NERD, reflux other than acid reflux can not be detected by conventional pH monitoring. The purpose of this study was to clarify the usefulness of multichannel intraluminal impedance-pH (MII-pH) monitoring for PPI-refractory NERD patients and examine the pathogenesis. We used MII-pH monitoring to examine 29 PPI-refractory NERD patients on PPI treatment. Reflux parameters, symptom index (SI: positive if ≥ 50%), and proximal migration were analyzed. The acidity of the reflux was divided into acid (nadir pH ≤ 4) and non-acid (nadir pH > 4). Subjects were classified into reflux-related disease (abnormal reflux parameters or positive SI) and non-reflux-related disease (normal reflux parameters and negative SI). Of the 29 subjects, 21 were diagnosed with reflux-related disease, including 6 with acid reflux type and 15 with non-acid reflux type, and 8 were diagnosed with non-reflux-related disease. Of the total 1816 liquid reflux episodes, 834 showed proximal migration, which was more common in symptomatic reflux than in asymptomatic reflux. MII-pH monitoring could distinguish reflux-related disease (especially non-acid type) from PPI-refractory NERD. Proximal migration was associated with symptomatic reflux in PPI-refractory NERD patients.

24 Versus 48-hour Bravo pH Monitoring

Historical ambulatory pH monitoring systems for the evaluation of gastroesophageal reflux disease have been catheter based and uncomfortable for patients, commonly limiting both their diet and activities. Catheter-based studies have also been reported to underestimate the amount of reflux a patient may have in a normal, routine day. Compared with conventional catheter-based pH monitoring systems, wireless (Bravo) pH monitoring is better tolerated by patients and allows for an increased duration of pH recording. Currently, there is lack of data regarding the optimal duration of wireless studies and concern that day 1 results are not typical of a patient's routine lifestyle, given the effects of sedation. Few studies have evaluated the merits of 24 versus 48-hour wireless pH monitoring. The aims of this study were (1) to identify differences in reflux parameters between 24 versus 48-hour testing as measured by wireless pH monitoring and (2) to assess the effect of 48-hour studies on the number of reflux episodes and symptom correlation as compared with 24-hour studies. A retrospective chart review of 124 consecutive patients who underwent 48-hour wireless esophageal pH monitoring studies was prepared. All patients underwent esophagogastroduodenoscopy using intravenous conscious sedation before wireless capsule placement. Acid reflux variables (including total reflux time, number of reflux episodes, and total percent time of pH<4) and symptom-association probability (SAP) scores were compared for day 1 versus day 2 versus total. Forty-eight-hour SAP scores were significantly higher when compared with the first 24 hours for all reported primary symptoms. SAP scores were calculated at 24 and 48 hours, respectively for heartburn (56 vs. 65, P<0.0001), regurgitation (65 vs. 80, P<0.0001), chest pain (59 vs. 78, P=0.0009), and cough (55 vs. 64, P=0.0027). In addition, the percentage of SAP scores >95 was significantly higher for both heartburn and regurgitation (34% vs. 48%, P=0.003 and 38% vs. 62%, P=0.005). As expected, 48-hour testing also captured a significantly higher number of reflux episodes as compared with day 1 results alone (97 vs. 47, P<0.0001). There were no statistical differences noted between the 2 days for total percent time of pH <4. Forty-eight-hour wireless (Bravo) pH monitoring strengthens symptom correlation as compared with 24-hour results alone and yields a greater percentage of SAP scores >95 for typical symptoms of gastroesophageal reflux disease. Prolonged recording of patient symptoms and/or sedation effects may account for the better symptom correlation. Although there were no statistical differences seen in this study between 24 and 48-hour studies for total percent time pH <4, 48-hour studies captured significantly more reflux episodes as compared with 24 hours of monitoring alone. These results suggest that patients undergoing wireless pH monitoring should have 48-hour studies performed as a standard of practice.

Wireless pH capsule – yield in clinical practice

Wireless pH monitoring is one of the recent technologies that focus on improving the diagnosis of gastroesophageal reflux disease (GERD). The capsule, which is fixed within the esophagus, transmits data via telemetry to an external receiver. The capsule is usually inserted 6 cm above the squamocolumnar junction during an upper endoscopy. The standard recording duration is 48 hours but this can be extended to 96 hours. The wireless capsule has been shown to be at least as accurate as the conventional catheter for the monitoring of esophageal pH. Normal pH values have been established in three different series. The use of a wireless capsule provides an increased diagnostic yield for GERD compared with the conventional catheter. The increased yield is the result of higher sensitivity to detect both abnormal acid esophageal exposure and positive symptom-reflux association. This may be related both to the prolonged recording duration and to fewer dietary modifications and restrictions on activities. Several studies have shown that the pH capsule was better tolerated by patients than the conventional pH catheter. Mild-to-moderate chest pain represents the main side effect of the pH capsule: severe chest pain requiring endoscopic removal of the capsule is rare. The main indication for wireless capsule application is monitoring of distal esophageal pH for diagnostic purpose, particularly in patients with a normal endoscopic examination. The capsule technique has some limitations: costs are higher than conventional pH monitoring, misplacement may occur, and the sampling rate is lower. Finally, compared with pH-impedance monitoring, only acid reflux events can be evaluated.

Nocturnal Gastroesophageal Reflux: Assessment and Clinical Implications

Nocturnal Gastroesophageal Reflux: Assessment and Clinical Implications

Laboratory based investigations for diagnosing gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) still remains the most common out- GI-related condition in the out-patient setting. While primary care physicians often use empiric trials with proton pump inhibitors (PPI trial) to diagnose GERD, often specialised tests are required to confirm or exclude gastroesophageal reflux causing esophageal or extraesophageal symptoms. The most commonly used procedures to diagnose GERD include: conventional (catheter based) pH monitoring, wireless esophageal pH monitoring (Bravo), bilirubin monitoring (Bilitec), and combined multichannel intraluminal impedance-pH monitoring (MII-pH). Each technique has strengths and limitations of which clinicians and investigators should be aware when deciding which one to choose.

Combined Multichannel Intraluminal Impedance and pH Monitoring for Patients With Suspected Laryngopharyngeal Reflux: Is It Ready to Use?

Combined Multichannel Intraluminal Impedance and pH Monitoring for Patients With Suspected Laryngopharyngeal Reflux: Is It Ready to Use?

Comparison of Esophageal pH and Multichannel Intraluminal Impedance Testing in Pediatric Patients With Suspected Gastroesophageal Reflux

Multichannel intraluminal impedance (MII) is a pH-independent method of assessing gastroesophageal reflux. To evaluate the diagnostic accuracy of MII-pH as compared with conventional pH monitoring in detecting reflux events (REs) and symptom association in different age groups. : A prospective direct comparison of 2 diagnostic techniques on 291 consecutive patients referred for suspected gastroesophageal reflux disease. Sensitivity and diagnostic accuracy of MII-pH versus pH monitoring and symptom association were measured. MII-pH detected 13631 REs, 6260 (46%) of which were nonacid. The prevalence of weakly acid refluxes in the 24 hours and postprandial period as well as the proximal extension of refluxate were significantly greater in infants as compared with children (P < 0.001, P < 0.001, and P < 0.01, respectively). The diagnostic accuracy of combined MII-pH in revealing all RE and acid RE were significantly higher in infants as compared with children (92% vs 82%, P < 0.01 and 83% vs 76%, P < 0.04, respectively). The addition of MII to conventional pH monitoring significantly increases the diagnostic yield of symptom association analysis in revealing an association between atypical symptoms and refluxes irrespective of age, whereas in studying typical symptoms it was true only for infants. Addition of MII to conventional pH monitoring significantly increases the diagnostic yield in detecting REs, prevalently in infants, and in revealing an association between refluxes and symptoms, prevalently respiratory ones and in infants group.

Comparative study of two modes of gastroesophageal reflux measuring: conventional esophageal pH monitoring and wireless pH monitoring

Esophageal pH monitoring is considered to be the gold standard for the diagnosis of gastroesophageal acid reflux. However, this method is very troublesome and considerably limits the patient's routine activities. Wireless pH monitoring was developed to avoid these restrictions. To compare the first 24 hours of the conventional and wireless pH monitoring, positioned 3 cm above the lower esophageal sphincter, in relation to: the occurrence of relevant technical failures, the ability to detect reflux and the ability to correlate the clinical symptoms to reflux. Twenty-five patients referred for esophageal pH monitoring and with typical symptoms of gastroesophageal reflux disease were studied prospectively, underwent clinical interview, endoscopy, esophageal manometry and were submitted, with a simultaneous initial period, to 24-hour catheter pH monitoring and 48-hour wireless pH monitoring. Early capsule detachment occurred in one (4%) case and there were no technical failures with the catheter pH monitoring (P = 0.463). Percentages of reflux time (total, upright and supine) were higher with the wireless pH monitoring (P < 0.05). Pathological gastroesophageal reflux occurred in 16 (64%) patients submitted to catheter and in 19 (76%) to the capsule (P = 0.355). The symptom index was positive in 12 (48%) patients with catheter pH monitoring and in 13 (52%) with wireless pH monitoring (P = 0.777). 1) No significant differences were reported between the two methods of pH monitoring (capsule vs catheter), in regard to relevant technical failures; 2) Wireless pH monitoring detected higher percentages of reflux time than the conventional pH-metry; 3) The two methods of pH monitoring were comparable in diagnosis of pathological gastroesophageal reflux and comparable in correlating the clinical symptoms with the gastroesophageal reflux.

Reflux monitoring: pH-metry, Bilitec and Oesophageal impedance measurements

Gastro-oesophageal reflux disease (GERD) is a highly prevalent condition in Western countries leading to millions of outpatient visits per year. GERD symptoms including heartburn, regurgitation and chest pain are caused by reflux of gastric content in the oesophagus even in the absence of endoscopically visible mucosal lesions. Several procedures are used to identify gastro-oesophageal reflux, the clinically widely used are: conventional (catheter-based) pH monitoring, wireless oesophageal pH monitoring (Bravo), bilirubin monitoring (Bilitec), and combined multichannel intraluminal impedance-pH monitoring (MII-pH). Each technique has strengths and limitations of which clinicians and investigators should be aware when deciding which to choose in a particular patient. Important is the ability to quantify gastro-oesophageal reflux and evaluate the relationship between symptoms and reflux episodes. The present review summarises the technical aspects in performing and interpreting esophageal reflux monitoring procedures.

S1897 Peroral Non-Endoscopic BRAVO™ Wireless pH Capsule Insertion Versus Conventional Catheter-Based pH Monitoring: A Prospective, Randomized Trial

S1897 Peroral Non-Endoscopic BRAVO™ Wireless pH Capsule Insertion Versus Conventional Catheter-Based pH Monitoring: A Prospective, Randomized Trial

Katheterfreie pH-Metrie mittels Bravo-Kapsel versus Standard-pH-Metrie bei Patienten mit nicht erosiver Refluxkrankheit (NERD)

pH-monitoring is considered the gold standard for the detection of acid reflux in patients with non-erosive reflux disease (NERD). Preliminary pH studies performed over periods longer than 24 hours have shown that in up to one-third of subjects abnormal pH exposure is detected only on the second day of monitoring. Therefore, pH-monitoring during 48 hours may yield more information about pathological acid reflux in patients being investigated for NERD. The aim of this study was to compare conventional 24-hour pH-monitoring with the new wireless 48-hour Bravo pH-monitoring in patients with NERD. Patients with typical reflux symptoms, a positive reflux disease questionnaire and negative endoscopy (NERD) and without any form of acid suppressive therapy were included in this prospective study. The patients were divided into two groups: group A for conventional 24-hour pH-monitoring and group B for wireless 48-h Bravo pH-monitoring. 76 patients with a diagnosis of NERD based on a positive RDQ questionnaire and negative endoscopy were included. (47 woman, 29 men, median age: 49 years). 54 underwent conventional pH-monitoring and 22 underwent 48-h pH-monitoring with the new wireless BRAVO system. The overall incidence of acid reflux was 55 % in patients with NERD. Acid reflux was detected less frequently when using Bravo as compared to conventional pH-monitoring. In addition, the Bravo pH-metry showed a large day-to-day variability. Prolonged pH-monitoring over a period longer than 24 hours did not improve the detection of acid reflux in patients with NERD. Thus, it appears that the Bravo pH-metry does not offer an advantage over standard pH-metry in the daily clinical practice.