Abnormal Acid Exposure Time Research Articles

Gastroesophageal reflux disease after peroral endoscopic myotomy: lest we forget what we already know.

After the performance of the first peroral endoscopic myotomy (POEM) in 2008, POEM has now spread worldwide and has arguably become a first-line treatment option for achalasia. Recently, there is increasing debate regarding post-POEM gastroesophageal reflux (GER) and gastroesophageal reflux disease (GERD). The reported incidences of GERD vary widely, owing to the variability in the definitions used. The literature regarding GERD and achalasia patients with a focus on 24-hour pH testing, esophageal acid exposure, and fermentation and the definitions of GERD used in the POEM literature are examined. 24-hour pH testing in achalasia patients may be abnormal due to fermentation both pre- and post-treatment. It is vital that POEM operators ensure that fermentation is recognized during 24-hour pH testing and excluded in the analysis of acid exposure time (AET) used in the diagnosis of GERD. In untreated achalasia, 24-hour pH testing may suggest abnormal AET in over a third of patients. However, most abnormal AETs in untreated achalasia patients are due to fermentation rather than GER. In treated achalasia, up to half of the patients with abnormal AET may be attributable to fermentation. To have a candid discussion and appropriately address the questions surrounding post-POEM GERD, consistent definitions need to be applied. We suggest the recent definition of GERD from the Lyon Consensus to be utilized when diagnosing GERD in post-POEM patients. Further studies are required in establishing ideal parameters for 24-hour pH testing in achalasia patients.

Endoscopic measurement of gastric pH associates with persistent acid reflux in patients treated with proton-pump inhibitors for gastroesophageal reflux disease.

Proton-pump inhibitors (PPIs) are the mainstay of gastroesophageal reflux disease (GERD) treatment, however, up to 30% of patients have a poor symptomatic response. PH-impedance is the gold standard to assess whether this is due to persistent acid reflux. We aimed to characterize clinical predictors of persistent esophageal acid reflux on PPIs including gastric pH measured during endoscopy. We prospectively recruited patients with GERD and/or Barrett's esophagus (BE) on PPIs. All patients completed a symptom questionnaire (RDQ) and underwent gastroscopy with gastric pH analysis, immediately followed by ambulatory 24-hour pH-impedance. We used a modified cut-off of 1.3% for pathological esophageal acid exposure time (AET). Multiple linear regression model was used to analyze the correlation between AET and predictive variables. We recruited 122 patients, of which 92 (75.4%) were included in the final analysis [44 male (47.8%), median age 53 years (IQR: 43-66)]. Forty-four patients (47.8%) had persistent acid reflux with a median total AET of 2.2 (IQR1.2-5.0), as compared to 0.1 (IQR 0.0-0.2) in patients without persistent reflux (n=48; P<.001). There was no difference in age, gender, BMI, PPI-regimen, diagnosis of hiatus hernia or BE, and severity of symptoms between patients with normal and abnormal AET. Median gastric pH was significantly lower in patients with abnormal AET (5.8 vs 6.6, P=0.032) and it correlated with the total AET (P=.045; R2=12.0%). With a pH cut-off of 5.05, single point endoscopic gastric pH analysis had an area under the ROC curve (AUC) of 63.0% (95%CI 51.3-74.7) for prediction of pathological esophageal AET. Symptoms and clinical characteristics are not useful to predict persistent acid reflux in patients on PPIs. One-point gastric pH correlates with 24-hour esophageal AET and could guide clinicians to assess response to PPIs, however, its utility needs validation in larger studies.

Analysis of clinical features and motility characteristics of ineffective esophageal motility

Objective To clarify the correlation between the clinical characteristics, esophageal motility features and esophageal acid exposure in patients with ineffective esophageal motility (IEM). Methods From January 2016 to March 2018, at Peking University First Hospital, 22 IEM patients diagnosed by esophagus high-resolution manometry (HRM) and 24 individuals with normal HRM results were enrolled. Clinical features, parameters of esophageal HRM and results of esophageal 24-hour pH monitoring of IEM patients and the individuals with normal HRM results were compared. According to the median distal contraction integral (DCI) of ten swallows, the IEM patients were divided into mild-IEM group (DCI 250-450 mmHg·s·cm (1 mmHg=0.133 kPa)) (14 cases) and severe-IEM group (DCI<250 mmHg·s·cm) (eight cases). The clinical features and esophageal motility were compared between normal HRM group, mild-IEM group and severe-IEM group. T test, chi-square test and one-way analysis of various were used for statistical analysis. Results The age of IEM group was older than that of normal HRM group ((64.5±11.2) years vs. (50.3±18.2) years), and the difference was statistically significant (t=-3.135, P=0.003). The lower esophageal sphincter pressure (LESP) of IEM group was lower than that of normal HRM group ((17.0±6.8) mmHg vs. (22.3±7.2) mmHg), and the difference was statistically significant (t=2.516, P=0.016). There were 15 cases in normal HRM group and 14 patients in IEM group who underwent esophageal 24-hour pH monitoring and there were five and two patients with abnormal acid exposure time (AET) in normal HRM group and IEM group, respectively. The length of proximal esophageal body (PEB) pressure zone of severe-IEM group was shorter than those of normal HRM group and mild-IEM group ((2.8±1.5) cm vs.(4.2±0.7) cm and (4.6±0.9) cm), and the differences were statistically significant (t=2.397 and 3.432, P=0.044 and 0.003). The integrated relaxation pressure (IRP) and LESP of normal HRM group were both higher than those of mild-IEM group ((9.3±2.9) mmHg vs. (7.2±3.3) mmHg, (22.3±7.2) mmHg vs. (15.4±7.1) mmHg), and the differences were statistically significant (t=2.148 and 2.843, P=0.038 and 0.007). There were six and eight patients in mild-IEM group and severe-IEM group who underwent esophageal 24-hour pH monitoring, respectively, and two patients in mild-IEM had abnormal AET. Conclusions The LESP of IEM patients is low. The clinical features and AET of IEM patients are not associated with the severity of IEM. In patients with severe IEM, the proximal and distal esophageal contractility is weakened, and the length of PEB pressure zone is shortened. Key words: Esophageal sphincter, upper; Ineffective esophageal motility; High-resolution manometry; Proximal esophageal body

Fragmented and failed swallows on esophageal high-resolution manometry associate with abnormal reflux burden better than weak swallows.

Association between proportions of hypomotile swallows on esophageal high-resolution manometry (HRM) and esophageal reflux burden remains incompletely understood. We investigated relationships between hypomotility, acid exposure time (AET), and mean nocturnal baseline impedance (MNBI) on ambulatory reflux monitoring. Clinical data, HRM, and ambulatory pH-impedance studies (performed off acid suppression) from patients with persisting reflux symptoms were reviewed from five international centers. AET (abnormal>6%) and MNBI (abnormal<2292ohms) were extracted from pH-impedance studies. Distal contractile integral (DCI) designated esophageal peristalsis into normal (DCI>450mmHg.cm.s), fragmented (DCI>450mmHg.cm.s with breaks>5cm), weak (DCI 100-450mmHg.cm.s), and failed (DCI<100mmmmHg.cm.s) sequences. Univariate and multivariate analyses were performed to identify motor associations of abnormal reflux burden. Of 351 patients (52.1±0.8years, 67%F), 29.3% had AET>6% and 61.8% had MNBI<2292ohms. On univariate analysis, both fragmented peristalsis and IEM associated with abnormal AET (P≤.01) and MNBI (P≤.03); reflux burden was more profound with >70% fragmented as well as ineffective sequences compared to ≤70% for each (P<.05 for each comparison). When weak and failed sequences within IEM were separately analyzed, ≥50% failed sequences predicted abnormal AET (P≤.009), and ≥50% weak sequences did not (P=.14). On multivariate regression, ≥50% failed sequences predicted abnormal AET (P=.02), and >70% ineffective sequences trended strongly (P=.069); >70% ineffective sequences predicted abnormal MNBI (P=.046), and >70% fragmented sequences trended strongly (P=.076). Breaks in esophageal peristaltic integrity seen with fragmented and failed sequences are more relevant to abnormal esophageal acid burden than weak sequences.

Mean Nocturnal Baseline Impedance Correlates With Symptom Outcome When Acid Exposure Time Is Inconclusive on Esophageal Reflux Monitoring

Abnormal acid exposure time (AET) is associated with good outcomes of symptoms from antireflux therapy. Low esophageal mean nocturnal baseline impedance (MNBI) is an additional marker of reflux disease. We aimed to evaluate the value of MNBI when analysis of AET produces borderline or inconclusive results. We studied a retrospective cohort of 371 patients (mean age, 54.5 ± 0.7 y; 60.0% female) who had persistent reflux symptoms after treatment and underwent ambulatory pH-impedance monitoring off antisecretory therapy at 1 tertiary center in Europe or 1 in the United States. Total AET was determined from pH impedance studies (pathologic, >6%; physiologic, <4%; borderline or inconclusive, 4%-6%). Baseline impedance values were calculated at the 5-cm impedance channel at 3 nocturnal 10-minute periods and averaged to yield MNBI (abnormal, <2292 ohms). The primary outcome was response to antireflux therapy, defined as global symptom improvement of 50% or greater on patients' answers on standardized visual analog scales. Among the 371 patients, 107 (28.8%) had pathologic AET and 234 (63.1%) had abnormal MNBI. Low MNBI was concordant in 99.1% of patients with pathologic AET, in 91.2% with borderline AET, and in 33.7% with physiologic AET. During 38.7 ± 0.8 months of follow-up evaluation, 43.0% of patients had improved symptoms with medical therapy and 76.2% had improved symptoms with surgical antireflux therapy (P < .0001). When MNBI was low, response to medical therapy did not differ significantly between patients with borderline AET and patients with pathologic AET (P= .44), but did differ significantly when each group was compared with patients with physiologic AET, regardless of whether MNBI was normal or low (P < .0001 for each comparison). When low, MNBI identifies patients with pathologic and borderline AET who respond to antireflux therapy. MNBI analysis complements AET in defining esophageal reflux burden. MNBI correlates with response of symptoms to antireflux therapy.

Eficacia diagnóstica de la impedancia basal nocturna media, un nuevo parámetro para el estudio de la enfermedad por reflujo gastroesofágico

Introducción y objetivos: el análisis de la impedancia basal nocturna media (IBNM) se ha propuesto para incrementar la precisión diagnóstica de enfermedad por reflujo erosiva (ERGE). Nuestro objetivo fue evaluar el rendimiento diagnóstico de esta prueba en un grupo de pacientes con ERGE conocida.Materiales y métodos: incluimos 123 individuos (58 con ERGE y 65 controles sanos) a quienes se les realizó pH-impedanciometría (pH-IMM) consecutiva entre enero de 2015 y junio de 2017. Todos los pacientes tenían endoscopia tomada en los 6 meses previos. El tiempo de exposición ácida (TEA) anormal (&gt;4,2%) y la presencia de pirosis y/o regurgitación en los 6 meses previos fueron los criterios para el diagnóstico de ERGE. Se encontraron 58 pacientes con ERGE, 24 con enfermedad por reflujo erosiva (ERE) y 34 con enfermedad por reflujo no erosiva (ERNE). Los 65 restantes fueron controles sanos (CS) asintomáticos con EGD y pH-IMM normales. Todos los trazos de pH-IMM se reanalizaron para medir la IBNM por un segundo observador que desconocía los datos previos. El análisis estadístico incluyó pruebas múltiples de Bonferroni para comparar los grupos; regresión lineal para variables continuas; y análisis de curva ROC para buscar valor IBNM con mayor rendimiento. Para los diferentes parámetros de precisión diagnóstica se utilizó el punto de corte de la IBNM. Se usó significancia estadística con valor de p &lt;0,01 e intervalos de confianza de 95% (IC 95%) para todos los cálculos.Resultados: los pacientes con ERE y ERNE presentaron valores de IBNM significativamente más bajos que el grupo control (p &lt;0,01). Se observó una correlación negativa entre los valores de la IBNM y TEA (r = 0,59; p = &lt;0,001), y también entre la IBNM y número de eventos de reflujo (r = 0,37; p = &lt;0,001). En el análisis de curva ROC, el área bajo la curva de la IBNM fue de 0,941 (IC 95%: 0,894-0,987) y el punto de corte con mayor eficiencia 1102 ohms (sensibilidad 98,5%; especificidad 84,5%). Usando este valor (&lt;1,102), la IBNM tuvo una sensibilidad para detectar ERGE de 91% (ERNE 86% y ERE 100%) y una especificidad de 98%.Conclusión: la IBNM tiene alta sensibilidad y especificidad para el diagnóstico de la ERGE. Adicionar esta prueba al análisis convencional de la pH-impedancia y a los métodos actuales de estudio de la ERGE puede mejorar significativamente nuestra capacidad para diagnosticar la enfermedad.

Intra-bolus pressure and esophagogastric gradient, assessed with high-resolution manometry, are associated with acid exposure and proximal migration of refluxate.

Trans-sphincteric pressure gradient (TSPG) seems to play a relevant role in eliciting refluxes during transient lower esophageal sphincter relaxations (TLESRs). Intra-bolus pressure (IBP) is considered to be correlated to esophageal wall tone. We aimed to evaluate the relationship between IBP, TSPG during TLESRs and the dynamic properties of refluxate in gastroesophageal reflux disease. Sixteen non-erosive reflux disease (NERD), 10 erosive disease (ERD) patients and 12 healthy volunteers (HVs), underwent 24-hour impedance-pH monitoring and combined high-resolution manometry-impedance before and 60 minutes. After a meal, ERD patients presented a significantly lower mean IBP (4.7 ± 1.6 mmHg) respect to NERD patients (8.9 ± 2.8 mmHg) and HVs (9.2 ± 3.2 mmHg). NERD patients with physiological abnormal acid exposure time showed a mean IBP (10.4 ± 3.1 mmHg) significantly higher than that in NERD with pathological abnormal acid exposure time (5.1 ± 1.5 mmHg). The TSPG value was significantly higher during TLESRs accompanied by reflux than during TLESRs not associated with reflux, both in patients and in HVs. A significant direct correlation was found between IBP, TSPG and proximal spread of refluxes in patients and in HVs. Gastroesophageal reflux disease patients display different degrees of esophageal distension. An increased compliance of the distal esophagus may accommodate larger volumes of refluxate and likely facilitates the injuries development. Higher TSPG values appear to facilitate the occurrence of refluxes during TLESRs. In patients with NERD, higher TSPG and IBP values favor proximal spread of refluxate and hence may play a relevant role in symptom generation.

In ineffective esophageal motility, failed swallows are more functionally relevant than weak swallows.

Esophageal pressure topography (EPT) diagnosis of ineffective esophageal motility (IEM) can be non-specific with unclear clinical significance. To determine whether peristaltic vigor or lower esophageal sphincter (LES) integrity is associated with poor clearance and acid reflux in IEM. Bolus clearance on high-resolution impedance manometry (HRIM) and available reflux studies in patients with IEM were retrospectively reviewed. Bolus clearance was assessed using both line tracing and colored contour methods on HRIM. EPT parameters, bolus clearance, and acid reflux variables were explored. Eighty-eight patients with IEM were included. Bolus clearance occurred in 71% of all swallows, and 55.7% of patients had complete bolus transit (CBT, bolus clearance in ≥80% of swallows). Bolus clearance was impaired in swallows with distal contractile integral (DCI) <100mmHg•cm•s compared to DCI 100-450 (0.43 vs 0.79, P<.0001). A cutoff at DCI 100mmHg•cm•s was associated with clearance with an accuracy of 76% compared to 49% at DCI 450 (P=.0001 for both). A median DCI <100 was associated with a higher Eckardt score (9 vs 3, P=.03), and on reflux testing available in 47 patients, with abnormal acid exposure time (P=.002). Peristaltic reserve (PR) defined as (DCI of multiple rapid swallow/median DCI of wet swallows), integrated relaxation pressure, and resting lower esophageal sphincter pressure were not associated with clearance or acid exposure. Failed peristalsis, as defined by DCI <100mmHg•cm•s, is associated with impaired bolus clearance and more severe dysphagia in IEM, and likely abnormal acid exposure.

Sa1662 - In Ineffective Esophageal Motility, Failed Swallows are More Functionally Relevant than Weak Swallows

BACKGROUND Esophageal pressure topography (EPT) diagnosis of ineffective esophageal motility (IEM) can be non-specific with unclear clinical significance. AIMS To determine whether peristaltic vigor or lower esophageal sphincter (LES) integrity is associated with poor clearance and acid reflux in IEM. METHODS Bolus clearance on high-resolution impedance manometry (HRIM) and available reflux studies in patients with IEM were retrospectively reviewed. Bolus clearance was assessed using both line tracing and colored contour methods on HRIM. EPT parameters, bolus clearance, and acid reflux variables were explored. KEY RESULTS Eighty-eight patients with IEM were included. Bolus clearance occurred in 71% of all swallows, and 55.7% of patients had complete bolus transit (CBT, bolus clearance in ≥80% of swallows). Bolus clearance was impaired in swallows with distal contractile integral (DCI) <100 mmHg•cm•s compared to DCI 100-450 (0.43 vs 0.79, P < .0001). A cutoff at DCI 100 mmHg•cm•s was associated with clearance with an accuracy of 76% compared to 49% at DCI 450 (P = .0001 for both). A median DCI <100 was associated with a higher Eckardt score (9 vs 3, P = .03), and on reflux testing available in 47 patients, with abnormal acid exposure time (P = .002). Peristaltic reserve (PR) defined as (DCI of multiple rapid swallow/median DCI of wet swallows), integrated relaxation pressure, and resting lower esophageal sphincter pressure were not associated with clearance or acid exposure. CONCLUSIONS & INFERENCES Failed peristalsis, as defined by DCI <100 mmHg•cm•s, is associated with impaired bolus clearance and more severe dysphagia in IEM, and likely abnormal acid exposure.

Critical appraisal of Rome IV criteria: hypersensitive esophagus does belong to gastroesophageal reflux disease spectrum.

The Rome IV Committee introduced a major change in the classification of functional gastrointestinal disorders, proposing a more restrictive definition of gastroesophageal reflux disease (GERD). It was suggested that hypersensitive esophagus (HE) may sit more firmly within the functional realm. It was suggested that GERD diagnosis should be based upon abnormal acid exposure time (AET) only, implying no advantage of impedance-pH over pH monitoring. Symptom association probability (SAP), symptom index (SI) and heartburn relief with proton pump inhibitor (PPI) therapy were regarded as unreliable, whereas a lack of response to PPI was considered as evidence of functional heartburn. These assumptions are contradicted by numerous studies showing the clinical relevance of weakly acidic refluxes and the diagnostic utility of SAP, SI and new impedance parameters, namely the post-reflux swallow-induced peristaltic wave (PSPW) index and the mean nocturnal baseline impedance (MNBI). The PSPW index and MNBI provide significant diagnostic advantage, particularly in patients with normal AET who can be classified as HE when both parameters are abnormal, even though SAP and SI are negative. Visceral pain modulators are recommended by the Rome IV Committee despite scanty evidence of efficacy, but a positive outcome with medical or surgical anti-reflux treatment has been reported by several studies of HE patients. Therefore, we believe that patients with endoscopy-negative heartburn should be investigated by means of impedance-pH monitoring with analysis of PSPW index and MNBI: such an approach provides accurate identification of HE cases, who remain, in our opinion, within the realm of GERD and should be treated accordingly.

Predictive Accuracy of Ambulatory 24-hour Impedance in Estimating Abnormal Esophageal Acid Exposure Time in Patients with Symptomatic Gastroesophageal Reflux

Introduction: Twenty-four hour impedance-pH monitoring quantitatively describes gastroesophageal reflux disease (GERD) by detecting impedance reflux events and evaluating esophageal acid exposure time (EAET). However, clinical ambiguity arises when pH and impedance results differ in interpretation. Studies are often abnormal by acid exposure time, but normal by impedance measures of reflux. As the limit of normal total reflux events was determined in asymptomatic patients, we sought to analyze the predictive accuracy of 24-hour impedance in patients with symptomatic GERD. Methods: Seventy-two patients (mean age 55.5 ± 13.2 years, 75% female) with unmedicated, symptomatic GERD received 24-hour impedance-pH testing. The sensitivity, specificity, and area under the curve (AUC) were calculated for impedance reflux events using upright, recumbent, and total EAET values greater than 6.3%, 1.2%, and 4.2%, respectively, as gold standards. Values for number of reflux events were varied to determine the ideal combination of sensitivity, specificity, and AUC indices, which were then used to generate best cutoff values of impedance-measured reflux events. Results: Mean total EAET time was 10.5% ± 9.9%, and 46 (63.8%) patients had elevated total EAET > 4.2%. EAET in the upright and recumbent positions were elevated in 58.9% and 59.1% of patients, respectively. Patients experienced 46.4 ± 30.5 reflux events measured by impedance. Fifteen patients (20.8%) had an elevated number of reflux events. The current standard of total reflux events >73 had a sensitivity of 32.6% and a specificity of 100%. AUC analysis revealed a cutoff of >41 total reflux events had the best sensitivity and specificity, 69.6% and 80.7%, respectively (AUC 0.84, 95% CI [0.75-0.93]). AUC analysis confirmed that a cutoff of >41 was also optimal when compared to gold standards for upright and recumbent acid exposure. Conclusion: In patients with GERD, 62.8% had pathological levels of EAET, with a mean duration of total EAET twice that of normal. Only 20.8% had an elevated number of reflux events as previously determined by the upper 95th percentile of asymptomatic patients. The standard of >73 reflux events is weakly sensitive, but extremely specific for symptomatic GERD. AUC analysis indicates that a lower threshold of abnormal events, such as >41, optimizes sensitivity and specificity in symptomatic patients, and may be a more appropriate diagnostic measure for impedance-pH monitoring.

Esophageal acid exposure analysis: with or without impedance?

Background: The pH data of multichannel intraluminal impedance-pH testing (MII-pH) may be analyzed by using all pH drops (simulating traditional pH-monitoring) or only analyzing pH drops associated with impedance changes. It is unknown whether the acid exposure measurements would differ between these methods in a group of symptomatic patients. Methods: We evaluated MII-pH studies of patients from 2008 to 2013. Acid analysis was performed in two methods: 1. Creating non-mealtime pH measurements related to retrograde bolus movements (“pH-MII method”) 2. Creating non-mealtime pH measurements anytime the pH fell below 4 (“all-pH method”). Statistical analysis was performed using t-test, Fischer’s test, and logistic regression. Results: 121 patients were eligible. The mean percent total acid exposure time (4.05) was significantly higher in the all-pH method (vs. 1.63 p=0.001). The proportion of patients with abnormal acid exposure time (24.7%) and DeMeester score (24.8%) was higher in the all-pH method (vs. 8.3%, p=0.001; vs. 9.1%, p=0.002). Compared to those without a hiatal hernia (HH), more patients with a HH >2cm had significant differences between analysis methods in upright (19.4% vs. 5.56%, p=0.03), recumbent (29% vs. 6.67%; p=0.002), total time (45.2% vs. 6.67%, p=0.001), and DeMeester score (35.5% vs. 8.89%; p=0.001). Adjusting for age, sex, and PPI usage, HH remained a significant predictor of whether results would differ (OR 12; CI 3.34-42.8 total exposure, OR 8.75; CI 2.36-32.5 DeMeester). Conclusion: Analysis of esophageal acid exposure using all pH data detected more acid reflux than when incorporating impedance measures, particularly in those with a HH. This finding may relate to small volume reflux. Therefore analysis of all-pH reflux rather than just MII-pH should be considered in those patients with a HH.

Intra-bolus pressure and esophagogastric gradient, assessed with high-resolution manometry, are associated with acid exposure and proximal migration of refluxate

Trans-sphincteric pressure gradient (TSPG) seems to play a relevant role in eliciting refluxes during transient lower esophageal sphincter relaxations (TLESRs). Intra-bolus pressure (IBP) is considered to be correlated to esophageal wall tone. We aimed to evaluate the relationship between IBP, TSPG during TLESRs and the dynamic properties of refluxate in gastroesophageal reflux disease. Sixteen non-erosive reflux disease (NERD), 10 erosive disease (ERD) patients and 12 healthy volunteers (HVs), underwent 24-hour impedance-pH monitoring and combined high-resolution manometry-impedance before and 60 minutes. After a meal, ERD patients presented a significantly lower mean IBP (4.7 ± 1.6 mmHg) respect to NERD patients (8.9 ± 2.8 mmHg) and HVs (9.2 ± 3.2 mmHg). NERD patients with physiological abnormal acid exposure time showed a mean IBP (10.4 ± 3.1 mmHg) significantly higher than that in NERD with pathological abnormal acid exposure time (5.1 ± 1.5 mmHg). The TSPG value was significantly higher during TLESRs accompanied by reflux than during TLESRs not associated with reflux, both in patients and in HVs. A significant direct correlation was found between IBP, TSPG and proximal spread of refluxes in patients and in HVs. Gastroesophageal reflux disease patients display different degrees of esophageal distension. An increased compliance of the distal esophagus may accommodate larger volumes of refluxate and likely facilitates the injuries development. Higher TSPG values appear to facilitate the occurrence of refluxes during TLESRs. In patients with NERD, higher TSPG and IBP values favor proximal spread of refluxate and hence may play a relevant role in symptom generation.

OP‐24 ESOPHAGEAL BASELINE IMPEDANCE IN NEUROLOGICALLY IMPAIRED CHILDREN

Introduction:Dysphagia, feeding difficulties and gastro‐oesophageal reflux (GORD) are common complaints in neurologically impaired children. Motor pattern generators localised in the brain stem and CNS reflexes play a key role on controlling oesophageal peristalsis and lower oesophageal sphincter activity. Thus, it is not surprising that brain abnormalities may result in significant oesophageal motor dysfunction. In this prospective study we evaluated the differences in multichannel intraluminal impedance‐pH monitoring (MII‐pH monitoring) pattern between children with cerebral palsy (CP) and 2 groups of neurologically normal children with normal and abnormal MII‐pH monitoring. We mainly focused our attention on oesophageal baseline impedance (BI), which has been proposed as useful parameter in predicting GORD severity.Methods:Twenty children with CP and 40 neurologically normal children with suspected GORD underwent MII‐pH impedance. Classical MII‐pH impedance parameters as well as BI values in both proximal and distal oesophagus were analysed. MII‐pH monitoring was considered abnormal if acid exposure time (AET) was &gt;5% and/or SAP was &gt;95%.Results:Nine CP children had a diagnosis of GORD. Of neurologically normal children, 20 had an abnormal (GR‐A) and 20 a normal MII‐pH monitoring (GR‐B). A significant difference in the proportion of children with abnormal AET was found between CP and GR‐A (9/20 vs 17/20; p &lt; 0.05). GR‐A showed a significantly greater percentage of AET (15.97 [6.4–34.9]) than both CP (8.21 [0–31.9], p &lt; 0.05) and GR‐B (1.4, [0–4.5], p &lt; 0.0001), whereas between the latter groups CP showed a greater AET (p &lt; 0.05). Proximal BI values were significantly lower in CP (1759 [691–3133]Ω) than GR‐A (2396 [1080–3850]Ω, p &lt; 0.05) and GR‐B (3385 [2249–4817]Ω, p &lt; 0.0001). No difference in distal BI was found between in CP (1106 [279–3098]Ω) and GR‐A (1152 [246–2526]Ω), while was lower in CP than in GR‐B (2965 [1986–3984]Ω, p &lt; 0.001). Considering all patients as a whole group, an inverse correlation was found between distal BI and AET (r‐0.66; p &lt; 0.001), whereas within groups an inverse correlation was only confirmed in GR‐A pts (r‐0.67; p &lt; 0.001).Conclusions:Although an abnormal pH‐impedance monitoring was detected in almost half of children with CP, no correlation was found between the AET and BI values, suggesting that the latter cannot be used as predictor of reflux severity in this group of patients. The presence of low impedance values in both proximal and distal oesophagus in children with CP supports the view that in neurologically impaired children BI mainly reflects oesophageal motor abnormalities, which have been previously reported.

PP‐6 BOLUS CLEARANCE TIME IS ASSOCIATED WITH REFLUX SEVERITY AND IT IS INVERSELY CORRELATED TO BASELINE IMPEDANCE VALUES IN ADOLESCENTS WITH GASTROESOPHAGEAL REFLUX DISEASE

Aims:The role of esophageal clearance is still scarcely investigated in patients with gastroesophageal reflux disease (GERD). We aimed to assess esophageal clearance in adolescents by means of bolus clearance time (BCT) and to verify if there is any difference among subgroups of GERD patients according to endoscopic and impedance‐pH monitoring findings.Methods:We revised endoscopic and impedance‐pH monitoring (off‐therapy) data of 28 consecutive adolescents (range 12–16 years). We evaluated acid exposure time (AET), total number of reflux episodes, baseline impedance (BI), and BCT. According to impedance‐pH monitoring features, adolescents were grouped into pH/MII negative (normal AET and normal number of refluxes), and pH/MII positive (abnormal AET and/or abnormal number of refluxes). This latter were further subgrouped on the basis of abnormal/normal AET (pH+/‐) and abnormal/normal number of refluxes (MII+/‐). Finally, adolescents were also classified as erosive and non erosive reflux disease (ERD, NERD).Results:We observed 22 pH/MII positive adolescents (7 ERD and 15 NERD). Eight patients were further subgrouped as pH+/MII‐, 6 as pH‐/MII+ and 8 as pH+/MII+. BCT values (in seconds) progressively decreased from pH+/MII+, pH+/MII‐, pH‐/MII+ to pH‐/MII‐ (34.5 ± 8.1 vs. 22.0 ± 7.2 vs. 16.4 ± 4.5 vs. 10.1 ± 2.1, respectively; p &lt; 0.001), whereas BI gradually increased (1236 ± 358 vs. 1592 ± 762 vs. 1854 ± 567 vs. 3256 ± 743, respectively; p &lt; 0.001). There was an inverse correlation between BCT and BI, and a direct correlation between BCT and AET (p &lt; 0.0001) and ERD presence (p &lt; 0.0001).Conclusions:BCT seems to reflects reflux severity, and it is inversely correlated to BI, a marker of mucosal integrity, supporting the role of esophageal clearance in the GERD pathophysiology.

The impact of obesity on oesophageal acid exposure time on and off proton pump inhibitor therapy.

Obesity is associated with increased oesophageal acid exposure time (AET) in patients with gastro-oesophageal reflux (GER), and may decrease the effects of proton pump inhibitors (PPIs). To evaluate the effects of increased body mass on the ability of PPI therapy to decrease AET in patients with reflux symptoms. Acid exposure time profiles collected from adult patients using wireless pH-metry while on or off PPI therapy was retrospectively reviewed. Patients were separated into five body mass index (BMI) categories as defined by the World Health Organization. A multivariable logistic regression evaluated the association between abnormal AET and BMI groups while controlling for age, gender and pH capsule placement methods. The study group comprised 968 patients with 336 (34.7%) studied on a PPI and 632 (65.3%) studied off PPI therapy. AET (total greater than 5.3%) was found more frequently in the overweight (67%) and obese classes (74-80%) compared to those who were normal weight (40%) while off acid-suppressing medications (P<0.001). No significant differences were found between these groups when studied on acid-suppressing medications, and the proportion of patients with abnormal AET across BMI classes was similar regardless of taking a PPI either once or twice daily. This is the largest study to report on the relationship between BMI and oesophageal acid exposure time in patients with GER on and off PPI therapy. We conclude that obesity is related to increased acid exposure time, but with no significant difference in acid exposure time among different weight-based groups when taking a once or twice-daily PPI.

Esophagogastric junction contractility for clinical assessment in patients with GERD: a real added value?

The role of esophagogastric junction contractile integral (EGJ-CI) as assessed by high-resolution manometry (HRM) is unclear. We aimed to correlate the EGJ-CI with impedance-pH findings in gastro-esophageal reflux disease (GERD) patients. Consecutive patients with GERD symptoms were enrolled. All patients underwent upper endoscopy, HRM, and impedance-pH testing. The EGJ-CI was calculated using the distal contractile integral tool box during three consecutive respiratory cycles. The value was then divided by the duration of these cycles. A value below 13 was considered as a defective EGJ-CI. We also assessed EGJ morphology, esophageal acid exposure time (AET), number of reflux episodes (NRE), and symptom association analysis (SAA). A positive impedance-pH monitoring was considered in case of abnormal AET and/or NRE and/or positive SAA. Among 130 patients we enrolled, 91 had GERD (abnormal AET and/or elevated NRE and/or positive SAA) and 39 had functional heartburn (FH) (negative endoscopy, normal AET, normal NRE, and negative SAA). The GERD patients had a lower median value of EGJ-CI (11 [3.1-20.7] vs 22 [9.9-41], p<0.02) compared to FH patients. Patients with a defective EGJ-CI had, more frequently, a positive impedance-pH monitoring or esophageal mucosal lesions at endoscopy (p<0.05 and p<0.05, respectively) than patients with a normal EGJ-CI. An EGJ-CI cut-off value of 5mmHgcm yielded the optimal performance in identifying GERD at impedance-pH (sensitivity 89%-specificity 63%). A defective EGJ-CI at HRM is clearly associated with evidence of GERD at impedance-pH monitoring. Evaluating EGJ-CI may be useful to predict an abnormal impedance-pH testing.

Interrogation of esophagogastric junction barrier function using the esophagogastric junction contractile integral: an observational cohort study.

The esophagogastric junction contractile integral (EGJ-CI), designed similar to distal contractile integral (DCI), has been proposed as a metric to evaluate EGJ barrier function. We determined normative values and evaluated EGJ-CI in predicting esophageal acid exposure time (AET) and symptomatic outcome in this observational cohort study. High-resolution manometry (HRM) studies were reviewed in 188 patients (55.2 ± 0.9 years, 64% female) undergoing ambulatory pH monitoring off therapy. Dominant symptoms and global symptom severity (GSS) were determined on questionnaires initially and upon follow-up. EGJ-CI was measured using the DCI tool placed across the EGJ and compared to normal controls (n = 21, 27.6 ± 0.6 years, 52% female). EGJ-CI was calculated both for a single respiratory cycle (SRC, in mmHg.cm.s) and corrected for respiratory cycle (CRC, mmHg.cm). Univariate and multivariate analyses determined the predictive potential of EGJ-CI in terms of AET and post-therapy GSS at follow-up, controlling for medical versus surgical therapy. Mean EGJ-CI values were significantly lower when AET was abnormal; EGJ-CI/SRC and EGJ-CI/CRC were 86% concordant (r = 0.84). Using receiver operating characteristic analysis, values below 121.8 mmHg.cm.s (EGJ-CI/SRC) and 39.3 mmHg.cm (EGJ-CI/CRC) predicted abnormal AET best (sensitivity 0.61 and 0.65, specificity 0.61 and 0.57, respectively). On univariate and multivariate analysis, the EGJ-CI discriminated normal from abnormal AET better than conventional LES parameters (P ≤ 0.02). After 2.7 ± 0.1 years follow-up, EGJ-CI below identified thresholds predicted better symptom response to antireflux surgery compared to medical therapy (P = 0.009). EGJ-CI is a novel HRM metric that has potential to complement or replace currently used basal LES and EGJ parameters.

PWE-175 Prevalence of pathological gastroesophageal reflux in patients with severe oesophageal hypomotility who do not present with typical reflux symptoms

Introduction Oesophageal hypomotility (OH) disorders are characterised by a decrease in the vigour of distal oesophageal contractions. An estimated 21 to 49% of patients with pathological gastroesophageal reflux (GOR) also have associated OH. However, prevalence of pathological GOR in OH who do not present with reflux symptoms has not been characterised. Overlooked reflux in these patients may hamper the success in treatment and also increase the risk of long-term side effects from chronic reflux. The aim of this study was to investigate the prevalence of pathological GOR and clinical presentation of patients with severe OH who do not present typical gastroesophageal reflux disease (GORD) symptoms. Method All patients diagnosed with frequent failed peristalsis or absent peristalsis on oesophageal high resolution manometry during January 2013 – December 2014 were selected retrospectively. Exclusion criteria were having typical reflux symptoms (heartburn and/or regurgitation) and history of antireflux surgery. All patients underwent ambulatory 24 h reflux monitoring. pH cut off 4 was used and pathological GOR was defined as high acid exposure time (total >6.3%, supine >1.2%, upright >4.2%)1and/or high number of reflux events >73. Symptoms were reported by the patient during interview. P value Results In total, 78 patients (30 male, 48 female; mean age 55 [19–82]) were included. Pathological GOR was detected in 28/78 (36%) of the patients [abnormal acid exposure time: 12/78 (15%) upright, 11/78 (14%) supine, 12/78 (15%) total, abnormal number of reflux events 15/78 (19%)]. The most common symptoms in patients with pathological GOR: dysphagia 21/28 (75%), chest pain 11/28 (39%) and cough 9/28 (32%) and in patients without GOR: epigastric pain: 19/50 (38%), chest pain 18/50 (36%), dysphagia 16/50 (32%). Epigastric pain was more commonly reported in patients without pathological GOR (P Conclusion Pathological GOR is prevalent in one third of the patients with severe OH without typical GORD symptoms. Reflux monitoring maybe indicated in patients with severe OH regardless of their presenting symptoms. Disclosure of interest None Declared. Reference Johnson LF, DeMeester TR. Twenty-four-hour pH monitoring of the distal esophagus. A quantitative measure of gastroesophageal reflux. Am J Gastroenterol. 1974:62:325–332.

Mo1120 The First 30-min Basal Impedance Levels Highly Correlate With the 24-Hour Values and Lower Values Are Associated With a Positive 24-h Impedance-pH Monitoring

Objectives: Recent data indicate that low esophageal baseline impedance (BI) measurements may reflect the status of the esophageal mucosa. We aimed to correlate the first 30-min baseline impedance (BI) levels with the 24-h BI values in patients with heartburn and negative endoscopy. Moreover, we correlated those values with the results of 24-h impedancepH.Methods: Sixty patients with heartburn and negative endoscopy underwent 24-h impedance-pH testing off-therapy and were sub-categorized in: a) patients with abnormal acid exposure time (AET) and/or number of refluxes (NERD); b) patients with pathophysiological characteristics related to functional heartburn (FH). Impedance-pH tracks were manually evaluated to assess the mean 24-h BI (15-min time window for each hour, avoiding refluxes and swallowing) and the first 30-min BI after the placement of the probe. Moreover, AET, number of refluxes and symptom/reflux correlation (SAP) were measured. Results: NERD showed a higher mean AET (6.3±1.6% vs 0.6±0.3%, p<0.05) and reflux number (78.1±23 vs 15.4±9.8, p<0.05) compared to FH. FH had a 100% negative SAP. The first 30-min BI was lower in NERD (1126.9±144.5) than in FH (3867.5±486.8) (p<0.001). There were no differences between the 24-h BI and the 30-min BI in both groups (1126.9±144.5 vs 1101±215.4 in NERD and 3867.5±486.8 vs. 3624.4±347.5 in FH; p=n.s.). We found a strong inverse correlation between BI (24-h and 30-min) and AET or total number of reflux events (see Figure 1). Conclusions: The 30-min BI levels directly correlate with 24-h BI and inversely correlate with AET. Moreover, the 30-min BI levels appear much lower in patients with a diagnosis of NERD at impedance-pH testing.