pH Monitoring Research Articles

Development of an implantable sensor system for in vivo strain, temperature, and pH monitoring: comparative evaluation of titanium and resorbable magnesium plates

Biodegradable magnesium is a highly desired material for fracture fixation implants because of its good mechanical properties and ability to completely dissolve in the body over time, eliminating the need for a secondary surgery to remove the implant. Despite extensive research on these materials, there remains a dearth of information regarding critical factors that affect implant performance in clinical applications, such as the in vivo pH and mechanical loading conditions. We developed a measurement system with implantable strain, temperature, pH and motion sensors to characterize magnesium and titanium plates, fixating bilateral zygomatic arch osteotomies in three Swiss alpine sheep for eight weeks. pH 1–2 mm above titanium plates was 6.6 ± 0.4, while for magnesium plates it was slightly elevated to 7.4 ± 0.8. Strains on magnesium plates were higher than on titanium plates, possibly due to the lower Young's modulus of magnesium. One magnesium plate experienced excessive loading, which led to plate failure within 31 h. This is, to our knowledge, the first in vivo strain, temperature, and pH data recorded for magnesium implants used for fracture fixation. These results provide insight into magnesium degradation and its influence on the in vivo environment, and may help to improve material and implant design for future clinical applications.

Comparison of daytime and nighttime supine gastroesophageal reflux by pH monitoring of individuals with clinical suspicion of gastroesophageal reflux disease.

This study aims to compare pHmetric characteristics of diurnal and nocturnal supine reflux. We studied 500 consecutive individuals with clinical suspicion of gastroesophageal reflux disease (GERD) who underwent esophageal high-resolution manometry and prolonged ambulatory pH monitoring. Patients were classified with supine GERD pattern when the percentage of acid reflux time in the supine position was equal to or greater than 2.2%. Data on acid reflux in the supine position during daytime and nighttime recumbency were: (i) acid exposure time, (ii) number of reflux episodes, (iii) longest reflux episode, (iv) interval between the last meal and the supine position, (v) interval between the supine position and the first acid reflux episode, and (vi) reported symptoms. Of the 500 evaluated patients, 238 (48%) had GERD. Among these, supine pattern was observed in 134 (56%) patients, bipositional in 53 (23%), and orthostatic in 51 (21%). In patients with daytime recumbency, 112 (51% of 217) were pathological refluxers, with a mean DeMeester score of 45 ± 26. Total acid exposure time (P = 0.8) and reported Symptom Index (P = 0.2) did not differ depending on the period, whether diurnal or nocturnal. All other pHmetric parameters were lower during daytime recumbency. In conclusion, diurnal supine reflux has similar acid exposure time and temporal correlation between symptoms and reflux episodes as nocturnal supine reflux. Other pHmetric parameters are lower for diurnal supine reflux.

Comparative Efficacy of Dexlansoprazole, Pantoprazole, Esomeprazole, and Rabeprazole in Achieving Optimal 24-Hour Intragastric pH Control: A Randomized Crossover Study Using Ambulatory pH Monitoring.

Proton pump inhibitors (PPIs) regulate gastric acid reflux. Dexlansoprazole's efficacy in prolonging acid suppression compared to conventional PPIs and placebo requires evaluation. A prospective, randomized, placebo-controlled, five-way crossover pilot study was conducted on healthy volunteers comparing the potency of dexlansoprazole to conventional PPIs in which five patients were randomized into five treatment cohorts, including dexlansoprazole 60 mg, pantoprazole 40 mg, esomeprazole 40 mg, rabeprazole 20 mg, and placebo, assessing 24-hour intragastric pH using Z/pH Recorder (ZepHr®, Diversatek, Inc., Milwaukee, WI) and analyzing statistical differences via paired t-test. Dexlansoprazole showed significantly longer durations with pH > 4.0 compared to placebo(P < 0.001) and all other PPIs (P < 0.05) over 24 hours. Although not significant in the first 0-12-hour period, dexlansoprazole maintained significantly higher pH levels in the last 12-24-hour period compared to pantoprazole (P = 0.001) and esomeprazole (P = 0.044) but not with rabeprazole (P = 0.075). Additionally, during the 24-hour pH monitoring measured at 30-minute intervals, dexlansoprazole (mean pH = 3.98 ± 0.11) consistently showed higher values than pantoprazole (mean pH = 3.48 ± 0.12), rabeprazole (mean pH = 3.66 ± 0.05), esomeprazole (mean pH = 3.66 ± 0.05), and placebo (mean pH = 2.52 ± 0.12), indicating its superior potency. Dexlansoprazole's dual-delayed release mechanism demonstrates superior acid suppression compared to traditional PPIs and placebo in this pilot study. Larger studies are needed to further evaluate its long-term efficacy and safety.

Dual-sensing nano-yarns for real-time pH and temperature monitoring in smart textiles

Dual-sensing nano-yarns for real-time pH and temperature monitoring in smart textiles

S705 The Efficacy of Antireflux Mucosectomy (ARMS) and Antireflux Mucosal Ablation (ARMA) for Gastroesophageal Reflux Disease (GERD) by 24-Hour pH Monitoring: Systematic Review and Meta-Analysis

S705 The Efficacy of Antireflux Mucosectomy (ARMS) and Antireflux Mucosal Ablation (ARMA) for Gastroesophageal Reflux Disease (GERD) by 24-Hour pH Monitoring: Systematic Review and Meta-Analysis

Gold Nanowire Sponge Electrochemistry for Permeable Wearable Sweat Analysis Comfortably and Wirelessly.

Electrochemistry-based wearable and wireless sweat analysis is emerging as a promising noninvasive method for real-time health monitoring by tracking chemical and biological markers without the need for invasive blood sampling. It offers the potential to remotely monitor human sweat conditions in relation to metabolic health, stress, and electrolyte balance, which have implications for athletes, patients with chronic conditions, and individuals for the early detection and management of health issues. The state-of-the-art mainstream technology is dominated by the concept of a wearable microfluidic chip, typically based on elastomeric PDMS. While outstanding sensing performance can be realized, the design suffers from the poor permeability of PDMS, which could cause skin redness or irritation. Here, we introduce an omnidirectionally permeable, deformable, and wearable sweat analysis system based on gold nanowire sponges. We demonstrate the concept of all-in-one soft sponge electrochemistry, where the working, reference, and counter electrodes and electrolytes are all integrated within the sponge matrix. The intrinsic porosity of sponge in conjunction with vertically aligned gold nanowire electrodes gives rise to a high electrochemically active surface area of ∼67 cm2. Remarkably, this all-in-one sponge-based electrochemical system exhibited stable performance under a pressure of 10 kPa and 300% omnidirectional strain. The gold sponge biosensing electrodes could be sandwiched between two biocompatible sweat pads, which can serve as natural sweat collection and outflow layers. This naturally biocompatible and permeable platform can be integrated with wireless communication circuits, leading to a wireless sweat analysis system for the real-time monitoring of glucose, lactate, and pH during exercise.

Novel Technique to Diagnose Gastroesophageal Reflux Disease

Gastroesophageal reflux disease (GERD), which is commonly encountered in clinical practice, has become increasingly prevalent in Asia in recent years. Definitive diagnosis of GERD requires upper gastrointestinal endoscopy and ambulatory pH monitoring and is therefore challenging. Endoscopic lesions are usually not incorporated into the diagnostic criteria, and pH monitoring is expensive, complicated, and uncomfortable for patients. Studies have investigated novel methods for diagnosis of GERD. Mucosal integrity, evaluated by mucosal admittance or impedance, is impaired in GERD owing to microscopic epithelial changes. Measurement of mucosal integrity is simple and can be performed endoscopically. Mucosal impedance has been investigated as a method to differentiate between GERD, non-GERD, and eosinophilic esophagitis, and mucosal admittance provides evidence to support diagnosis of GERD. Further research on these novel techniques is warranted to incorporate these into the diagnostic modalities used for GERD.

Battery-Free and Multifunctional Microfluidic Janus Wound Dressing with Biofluid Management, Multi-Indicator Monitoring, and Antibacterial Properties.

The sophisticated environment of chronic wounds, characterized by prolonged exudation and recurrent bacterial infections, poses significant challenges to wound recovery. Recent advancements in multifunctional wound dressings fall short of providing comprehensive, accurate, and comfortable treatment. To address these issues, a battery-free and multifunctional microfluidic Janus wound dressing (MM-JWD) capable of three functions, including exudate management, antibacterial properties, and multiple indications of wound infection detection, has been developed. During the treatment, the fully soft microfluidic Janus membrane not only demonstrated stable unidirectional fluid transport capabilities under various skin deformations for a longer period but also provided antibacterial effects through surface treatment with chitosan quaternary ammonium salts and poly(vinyl alcohol). Furthermore, integrating multiple colorimetric sensors within the Janus membrane's microchannels and a dual-layer structure enabled simultaneous monitoring of the wound's pH, uric acid, and temperature. The monitoring was facilitated by smartphone recognition of color changes in the sensors. In vivo and in vitro tests confirmed the exudate management, antibacterial, and sensing capabilities of the MM-JWD, proving its efficacy in monitoring and promoting the healing of wounds. Overall, this study provides a valuable method for the design of multifunctional wound dressings for chronic wound care.

Development of a 3D Hydrogel SERS Chip for Noninvasive, Real-Time pH and Glucose Monitoring in Sweat.

Traditional diagnostic methods, such as blood tests, are invasive and time-consuming, while sweat biomarkers offer a rapid physiological assessment. Surface-enhanced Raman spectroscopy (SERS) has garnered significant attention in sweat analysis because of its high sensitivity, label-free nature, and nondestructive properties. However, challenges related to substrate reproducibility and interference from the biological matrix persist with SERS. This study developed a novel ratio-based 3D hydrogel SERS chip, providing a noninvasive solution for real-time monitoring of pH and glucose levels in sweat. Encapsulating the probe molecule (4-MBN) in nanoscale gaps to form gold nanoflower-like nanotags with internal standards and integrating them into an agarose hydrogel to create a 3D flexible SERS substrate significantly enhances the reproducibility and stability of sweat analysis. Gap-Au nanopetals modified with probe molecules are uniformly dispersed throughout the porous hydrogel structure, facilitating the effective detection of the pH and glucose in sweat. The 3D hydrogel SERS chip demonstrates a strong linear relationship in pH and glucose detection, with a pH response range of 5.5-8.0 and a glucose detection range of 0.01-5 mM, with R2 values of 0.9973 and 0.9923, respectively. In actual sweat samples, the maximum error in pH detection accuracy is only 1.13%, with a lower glucose detection limit of 0.25 mM. This study suggests that the ratio-based 3D hydrogel SERS chip provides convenient, reliable, and rapid detection capabilities with substantial application potential for analyzing body fluid pH and glucose.

Development of an osmosis-assisted hollow microneedle array integrated with dual-functional electrochemical sensor for urea and pH monitoring in interstitial fluid

In healthcare, accurate detection of biomarkers is paramount for disease diagnosis, prevention, and personal health surveillance. This study focused on developing and validating a MgCl2 deposited hollow microneedle array integrated with a dual-functional sensor system, which was used for osmosis-assisted boosted interstitial fluid extraction, the simultaneous and continuous monitoring of urea and pH in interstitial fluid. The urea sensor component was fabricated by electro-depositing prussian blue onto a carbon electrode, followed by applying a molecularly imprinted polymer layer, ensuring high specificity and sensitivity. The pH sensor was constructed through electropolymerization of polyaniline, exhibiting a linear response across a wide pH range. When tested in artificial skin matrix, the system demonstrated excellent in vitro electrochemical sensing performance with high linearity and repeatability. At the same time, the practical in vivo sensing performance of the system was verified in Sprague-Dawley (SD) rats. The development of the system underscores its potential as a valuable tool for continuous health monitoring.

Dual-Purpose Aptamer-Based Sensors for Real-Time, Multiplexable Monitoring of Metabolites in Cell Culture Media.

The availability of high-frequency, real-time measurements of the concentrations of specific metabolites in cell culture systems will enable a deeper understanding of cellular metabolism and facilitate the application of good laboratory practice standards in cell culture protocols. However, currently available approaches to this end either are constrained to single-time-point and single-parameter measurements or are limited in the range of detectable analytes. Electrochemical aptamer-based (EAB) biosensors have demonstrated utility in real-time monitoring of analytes in vivo in blood and tissues. Here, we characterize a pH-sensing capability of EAB sensors that is independent of the specific target analyte of the aptamer sequence. We applied this dual-purpose EAB to the continuous measurement of pH and phenylalanine in several in vitro cell culture settings. The miniature EAB sensor that we developed exhibits rapid response times, good stability, high repeatability, and biologically relevant sensitivity. We also developed and characterized a leak-free reference electrode that mitigates the potential cytotoxic effects of silver ions released from conventional reference electrodes. Using the resulting dual-purpose sensor, we performed hourly measurements of pH and phenylalanine concentrations in the medium superfusing cultured epithelial tumor cell lines (A549, MDA-MB-23) and a human fibroblast cell line (MRC-5) for periods of up to 72 h. Our scalable technology may be multiplexed for high-throughput monitoring of pH and multiple analytes in support of the broad metabolic qualification of microphysiological systems.

Wearable electrochemical device based on butterfly-like paper-based microfluidics for pH and Na+ monitoring in sweat

A wearable potentiometric device is reported based on an innovative butterfly-like paper-based microfluidic system, allowing for continuous monitoring of pH and Na+ levels in sweat during physical activity. Specifically, the use of the butterfly-like configuration avoids evaporation phenomena and memory effects, enabling precise and timely biomarker determination in sweat. Two ad hoc modified screen-printed electrodes were embedded in the butterfly-like paper-based microfluidics, and the sensing device was further integrated with a portable and miniaturized potentiostat, leveraging Bluetooth technology for efficient data transmission. First, the paper-based microfluidic configuration was tested for optimal fluidic management to obtain optimized performance of the device. Subsequently, the two electrodes were individually tested to detect the two biomarkers, namely pH and Na+. The results demonstrated highly promising near-Nernstian (0.056 ± 0.002 V/dec) and super-Nernstian (− 0.080 ± 0.003 V/pH) responses, for Na+ and pH detection, respectively. Additionally, several important parameters such as storage stability, interferents, and memory effect by hysteresis study were also investigated. Finally, the butterfly-like paper-based microfluidic wearable device was tested for Na+ and pH monitoring during the physical activity of three volunteers engaged in different exercises, obtaining a good correlation between Na+ increase and dehydration phenomena. Furthermore, one volunteer was tested through a cardiopulmonary test, demonstrating a correlation between sodium Na+ increase and the energetic effort by the volunteer. Our wearable device highlights the high potential to enable early evaluation of dehydration and open up new opportunities in sports activity monitoring.Graphical abstract

Epidermal secretion-purified biosensing patch with hydrogel sebum filtering membrane and unidirectional flow microfluidic channels

The development of biosensing electronics for real-time sweat analysis has attracted increasing research interest due to their promising applications for non-invasive health monitoring. However, one of the critical challenges lies in the sebum interference that largely limits the sensing reliability in practical scenarios. Herein, we report a flexible epidermal secretion-purified biosensing patch with a hydrogel filtering membrane that can effectively eliminate the impact of sebum and sebum-soluble substances. The as-prepared sebum filtering membranes feature a dual-layer sebum-resistant structure based on the poly(hydroxyethyl methacrylate) hydrogel functionalized with nano-brush structured poly(sulfobetaine) to eliminate interferences and provide self-cleaning capability. Furthermore, the unidirectional flow microfluidic channels design based on the Tesla valve was incorporated into the biosensing patch to prevent external sebum contamination and allow effective sweat refreshing for reliable sensing. By seamlessly combining these components, the epidermal secretion-purified biosensing patch enables continuous monitoring of sweat uric acid, pH, and sodium ions with significantly improved accuracy of up to 12 %. The proposed strategy for enhanced sweat sensing reliability without sebum interference shows desirable compatibility for different types of biosensors and would inspire the advances of flexible and wearable devices for non-invasive healthcare.

Sustainable gelatin-kappa carrageenan active packaging with Mekwiya date seeds to enhance goat meat quality and shelf life

This research aimed to elaborate a gelatin-Kappa carrageenan-based packaging with 0.22 %, 0.44 %, and 0.88 % w/v of Mekwiya date palm seeds extract (DSEMK). This extract improved the mechanical, physical, and thermal properties of the films. Moisture content, water solubility, and water vapor permeability were reduced from 17.54 ± 0.02 to 12.18 ± 0.02, from 77.61 ± 0.02 to 25.35 ± 0.29 %, and from 5.28 ± 0.29 to 1.69 ± 0.03 g s−1 m−1 Pa−1 × 10−10, respectively. During thermal degradation, DSEMK4 film had a residual weight of 27.99 %, compared to 20.67 % for the control. Despite a decline in the film's tensile strength from 24.19 to 8.94 MPa with the incorporation of DSEMK, elongation at the breaking point increased from 37.66 ± 0.16 to 46.17 ± 0.25 %. The film containing DSEMK4 displayed the highest phenolic contents and illustrated the best antioxidant effects in DPPH and FRAP assays, with IC50s of 756 and 1445 μg/mL, respectively and inhibited pathogen growth on the meat surface. Over storage at 4 °C, monitoring of pH, lipid and protein oxidation parameters, microbial spoilage, optical properties, and sensory attributes disclosed that the DSEMK-films successfully enhanced the meat quality and safety. These findings were supported by principal component analysis and heat maps.

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.

Flexible plasmonic microneedle array-based SERS sensor for pH monitoring of skin interstitial fluid

Interstitial fluid (ISF) is a prevalent accessible and information-rich biofluid, and monitoring pH level of interstitial fluid plays a crucial role in the physiological health assessment. However, facile extraction of ISF and sensitive detection of pH is still a great challenge. Herein, a flexible plasmonic microneedle array (PMNA)-based SERS sensor was developed for facile and sensitive pH monitoring of skin ISF. The flexible microneedle arrays were fabricated by norland optical adhesive 65 (NOA65), and coated with pH-sensitive 4-Mercaptobenzoic acid (4-MBA)-labeled silver nanoparticles (Ag NPs) by electrostatic assembly. The proposed flexible PMNA-based SERS sensor has a good linear response in the pH range of 5 to 9 which covers the normal pH level in skin interstitial fluid. The ISF extracted from porcine skin was chosen as the test model, and the pH levels detected by the PMNA-based SERS sensors were well consistent with the theoretical results. Besides, the proposed flexible SERS sensors show good mechanical robustness, sensing stability, and biocompatibility before and after skin insertion, which can be a potential analytical tool for practical detection of pH levels in ISF and provide technical support for SERS-based wearable biosensing.

455. SHOULD THE DIAGNOSTIC THRESHOLD FOR PH MONITORING IN GASTROESOPHAGEAL REFLUX DISEASE DIFFER BETWEEN THE EAST AND THE WEST?

Abstract Background The Montreal definition's reliance on troublesome typical symptoms alone is inadequate for diagnosing 'actionable' Gastroesophageal Reflux Disease (GERD). Lyon consensus 2.0 updated conclusive evidence of GERD, incorporating Los Angeles grade B or above esophagitis and Acid Exposure Time (AET) exceeding 6% in ambulatory reflux monitoring. The Seoul Consensus 2020 presents varied opinions on applying the same standards to the Asian population. A meta-analysis determined the Asian upper limit of AET as 3.2%. This study aims to compare Lyon 1.0 and 2.0 consensus compositions and assess the sensitivity and specificity of different AET thresholds in predicting Grade B or above esophagitis. Methods Patients with refractory GERD symptoms or considering anti-reflux surgery underwent objective GERD workup, including 24-hour catheter-based or 96-hour wireless ambulatory pH monitoring, High-Resolution Manometry, and upper endoscopy. This retrospective cohort study analyzed patient data from 2011-2023, excluding those with prior anti-reflux surgery, bariatric surgery, or myotomy for achalasia. Patients were categorized based on Lyon Consensus 1.0 and 2.0 as 'Non-GERD,' 'Borderline GERD,' 'Borderline GERD with evidence,' and 'Conclusive GERD.' Sensitivity, specificity, and Area-Under-Curve (AUC) were calculated using AET thresholds of 3.2%, 4%, 6%, and 7.2% to predict Grade B or above esophagitis. Results Between July 2011 and August 2023, 257 patients underwent pH monitoring and were included in the analysis, with 247 (93.8%) being ethnic Chinese. The number of patients categorized as conclusive GERD was significantly higher in Lyon 2.0 (134, 52.1%) compared to Lyon 1.0 (109, 42.4%), p &amp;lt; 0.001. Sensitivity and specificity for predicting Grade B or above esophagitis were as follows: AET 3.2% (83.3%, 48.8%), AET 4% (65.3%, 52.4%), AET 6% (73.8%, 66%), AET 7.2% (69.0, 72.1%). AET 7.2% demonstrated the highest AUC of 70.6% (Figure 1). Among patients classified as conclusive GERD, 67 (50%) underwent antireflux surgery. Conclusion Using the Asian threshold of AET 3.2% yields the highest sensitivity for detecting Grade B or above esophagitis. Additionally, the AUC is higher compared to using AET 4.0%. However, it is important to note that AET alone should not be the sole parameter for diagnosing actionable GERD, as even with the lowest AET threshold of 3.2%, 16.7% of patients with Grade B or above esophagitis would be missed.

586. VALUE OF PEPSIN IN SALIVA TO ASSESS THE POSTOPERATIVE OUTCOME OF PATIENTS WITH GERD

Abstract Background The aim of this study was to evaluate the value of salivary pepsin to assess the outcome of surgical treatment of patients with gastroesophageal reflux (GERD). Methods Forty-five consecutive patients with GERD despite proton pump inhibitor treatment received laparoscopic anti-reflux surgery (LARS). 24-hour esophageal pH-monitoring (MII-pH) and esophageal manometry (HRM) data were documented preoperatively and at 3-month follow-up. Clinical symptoms were rated with the Gastrointestinal Quality of Life Index (GIQLI) and gastrointestinal symptoms were evaluated by a standardized symptom checklist (SCL), assessing the severity and intensitiy of 14 different symptoms. Simultaneous to MII-pH the collection of 3 saliva samples per patient was performed. Treatment failure was defined as improvement of GIQLI and SCL of &amp;lt; 10 points, despite showing a normal DeMeester score. Results At baseline, all patients showed a pathological MII-pH measurement. Furthermore, all patients showed postoperatively a normal DeMeester score (mean 7.10 ± 4.56). Ten patients were defined as treatment failures with a change of pepsin concentration from a mean value of 198.73 ng/mL to 186.00 ng/mL (p&amp;gt;0.05). In patients defined as treatment success, mean pepsin value decreased from 205.83 ng/mL to 85.24 ng/mL (p&amp;lt;0.001). Conclusion Salivary pepsin could be a marker for treatment success after LARS. However, larger studies are required to reach firm conclusions.

363. REFLUX MICRO-ASPIRATION: WHAT HAVE WE LEARNED

Abstract Background The accurate diagnosis of gastro-oesophageal reflux pulmonary microaspiration has only become possible recently with the introduction of a novel technique of reflux micro-aspiration scintigraphy study combined with single photon emission computed tomography (SPECT) combined with x-ray tomography (CT) in a hybrid instrument. This has allowed the accurate diagnosis of pulmonary and airway contamination with refluxate. Previously only patients with large volume symptomatic reflux aspiration were diagnosed clinically (Mendelson syndrome) or by 2-dimentional barium meal or an older plantar (2 dimensional) technique of scintigraphic aspiration studies. The concept of reflux micro-aspiration has been implicated in multiple pulmonary diseases but without absolute proof from an adequate diagnostic test. Little was known about the natural history, physiology, and response to treatment amongst patients with silent reflux micro-aspiration. The aim of this presentation is to summarise a series of research projects studying the natural history of the disease, common presenting symptoms, pathophysiology and response to treatment. Methods A prospectively populated database of patients referred to a tertiary specialist reflux diagnostic service with atypical and/or treatment resistant reflux was evaluated. The database contained records of consecutive patients including demographic information, presenting symptoms, investigations including imaging, upper gastro-intestinal physiology studies and novel reflux micro-aspiration scintigraphy studies. Treatment details including medical and surgical treatment and post treatment clinical information and investigations. Multiple studies were conducted using the information from the database and findings are summarised in this presentation. Results The novel reflux micro-aspiration scintigraphy with SPECT/CT was compared with other studies (multichannel intraluminal impedance and 24-hour pH monitoring) and was found to be sensitive to reflux occurring outside the oesophagus. Patients with reflux micro-aspiration can present a wide variety of symptoms, commonly a combination of typical symptoms of gastro-oesophageal reflux disease (heartburn and regurgitation) and respiratory symptoms. Reflux micro-aspiration was associated with reduced lower oesophageal sphincter pressure, severe ineffective oesophageal motility (IOM), and pharyngeal contamination with refluxate on reflux scintigraphy. Delayed liquid gastric emptying was not associated with reflux micro-aspiration, however gastroparesis with solids is associated with micro-aspiration. Micro-aspiration was common in patients with giant hiatus hernias and mostly resolved with surgery. Anti-reflux surgery resulted in resolution of aspiration in the majority of patients, however severe IOM was associated with lesser rates of microaspiration resolution. Conclusion Reflux micro-aspiration appears to be a more common manifestation of GORD than previously thought. The work summarised in this presentation discusses the presentation, physiological associations, and treatment of patients with reflux micro-aspiration.

Long-term clinical evaluation of a decade with peroral endoscopic myotomy at a single European tertiary center

Peroral endoscopic myotomy (POEM) is an established treatment for achalasia with compelling midterm efficacy. In this study, we analyzed the long-term efficacy, sought predictors of failure, and comprehensively assessed post-POEM reflux. We performed a retrospective analysis of a prospective database of patients undergoing POEM at a high-volume center from December 2012 to June 2023. Patients who had completed a 3-month follow-up were included. Efficacy was assessed at 3, 6, and 8 years using the Eckardt score (ES). An ES≤2 was considered treatment success. At 3 months, gastroscopy, manometry, 24-hour pH monitoring, and fluoroscopy were performed, and gastroscopy was repeated at 2 and 3 years. At each visit, patients were assessed for reflux symptoms and quality of life. From 496 included patients, 3-, 6-, and 8-year follow-ups were completed in 302, 115, and 40 patients, respectively. The treatment success rates at 3, 6, and 8 years according to the Kaplan-Meier analysis were 90.2% (95% confidence interval [CI], 87.2-93.3), 82.3% (95% CI, 77.3-87.6), and 73.5% (95% CI, 64.8-83.5), respectively. Year of procedure was the only predictor of outcome. Fifty-three patients (10.7%) encountered failure or recurrence. Treatment success of redo-POEM (n= 20) at 1 year was significantly lower (62.9% [95% CI, 44.3-89.2] vs 96.9% [95% CI, 95.3-98.5], P< .001). At 3 months, 40.4% of patients had reflux esophagitis (RE), 43.6% of patients had an acid exposure time >4.5%, 39.2% of patients were using proton pump inhibitors (PPIs), but only 24.2% had reflux symptoms. At 2 to 3 years, 50.8% of patients took PPIs, whereas 39.6% were symptomatic. RE decreased to 20.2% at 6 years. The treatment success of POEM declines over time but remains sufficiently high in the long term. Experience with the procedure improves the outcome. Gastroesophageal reflux affects almost half of patients early after POEM and decreases substantially over time together with a rise in PPI use.