Esophageal Impedance Research Articles

Esophageal Baseline Impedance From High-resolution Impedance Manometry Correlates With Mean Nocturnal Baseline Impedance From pH-impedance Monitoring.

Background/AimsEsophageal baseline impedance (BI) can be extracted from pH-impedance tracings as mean nocturnal baseline impedance (MNBI), and from high-resolution impedance manometry (HRIM), but it is unknown if values are similar between acquisition methods across HRIM manufacturers. We aim to assess correlations between MNBI and BI from HRIM (BI-HRIM) from 2 HRIM manufacturers in the setting of physiologic acid exposure time (AET).MethodsHRIM and pH-impedance monitoring demonstrating physiologic AET (< 4%) off proton pump inhibitors were required. BI-HRIM was extracted as the average from 5 cm and 10 cm above the lower esophageal sphincter. Distal BI-HRIM (DBI-HRIM) was also extracted from the most distal channel (Medtronic studies). MNBI was extracted from 6 channels. Concordance between BI-HRIM across manufacturers with MNBI was analyzed.ResultsThirty-six patients met the inclusion criteria (59.6 ± 1.7 years; 22% female; body mass index 30.5 ± 0.7; AET 1.6 ± 0.2%). Although MNBI was similar at all channels (P ≥ 0.18), Diversatek BI-HRIM was lower than Medtronic BI-HRIM (P = 0.003). Overall, BI-HRIM correlated with MNBI at corresponding recording sites, 7 cm and 9 cm (P < 0.05), but not at other sites (P ≥ 0.19). Pearson’s correlations > 0.5 were seen at MNBI at 7 cm for both systems, and at 9 cm for Medtronic. DBI-HRIM correlated with MNBI at 3 cm and 5 cm (P < 0.03), but not at other locations (P > 0.1).ConclusionsWhile numeric differences exist between manufacturers, BI-HRIM correlates with MNBI from corresponding channels in patients with physiologic AET. Comparison with AET elevation is needed to determine correlations between pathologic MNBI with BI-HRIM across manufacturers. The optimal HRIM channels from which BI values should be extracted also warrants further study.

A single-center retrospective analysis of 46 children with aerophagia

To study the clinical features of aerophagia in children. A retrospective analysis was performed on the medical data of 46 children with aerophagia who were diagnosed and treated in Children's Hospital Affiliated to Nanjing Medical University from October 2011 to September 2019. Among these 46 children, 15 (33%) had Tourette syndrome. Abdominal distension was the most common symptom and was observed in 45 children (98%). The 24-hour esophageal multichannel intraluminal impedance monitoring showed a mean number of 341 times of air swallowing and a mean number of 212 times of gas reflux, and 95% of gas refluxes occurred in the upright body position. Compared with those without Tourette syndrome, the children with Tourette syndrome had a significantly higher incidence rate of air swallowing symptoms (67% vs 6%, P<0.001), but there were no significant differences in other symptoms and the results of 24-hour esophageal impedance. Dietary adjustment, psycho-behavioral therapy, and drug intervention significantly improved the scores of clinical symptoms and quality of life, among which psycho-behavioral therapy was an important intervention measure. Some children with aerophagia may have Tourette syndrome, and such children are more likely to have air swallowing symptoms. Psycho-behavioral therapy is one of the most important treatment methods, and children with aerophagia tend to have a good prognosis after treatment.

Relationship between distension-contraction waveforms during esophageal peristalsis: effect of bolus volume, viscosity, and posture.

High-resolution esophageal manometry (HRM) in its current form assesses only the contraction phase of peristalsis. Degree of esophageal distension ahead of contraction is a surrogate of relaxation and can be measured from intraluminal esophageal impedance measurements. The characteristics of esophageal contractions, i.e., their amplitude, duration, velocity, and modulating factors, have been well studied. We studied the effect of bolus volume and viscosity and posture on swallow-induced distension and contraction and the temporal relationship between the two. HRM impedance recordings of 50 healthy subjects with no esophageal symptoms were analyzed. Eight to ten swallows of 5 and 10 mL of 0.5 N saline and a viscous bolus were recorded in the supine and Trendelenburg positions. Custom-built computer software generated the distension-contraction plots and numerical data of the amplitudes of distension (cross-sectional area) and contraction, and the temporal relationship between distension and peak contraction. The hallmarks of distension waveforms are that 1) distension peak, similarly to contraction, travels the esophagus in a peristaltic fashion, and the amplitude of distension increases from the proximal-to-distal direction; 2) the amplitude of distension is greater with 10 mL than with 5 mL and greater in Trendelenburg than in supine posture; and 3) bolus viscosity increases the amplitude of distension and alters the temporal relationship between distension and contraction waveforms. We describe the characteristics of esophageal distension during peristalsis and the relationship between distension and contraction in a relatively large cohort of normal subjects. These data can be used to compare differences between normal subjects and patients with various esophageal motility disorders in future studies.NEW & NOTEWORTHY We studied esophageal distension (surrogate of inhibition) ahead of contraction during peristalsis from intraluminal esophageal impedance measurements. Esophageal distension, similarly to contraction, travels the esophagus in a sequential manner, and the amplitude of esophageal distension increases from proximal to distal direction in the esophagus. Bolus volume, viscosity and posture have significant effects on the amplitude of distension and its temporal relationship with contraction.

Esophageal contractile segment impedance from high-resolution impedance manometry correlates with mean nocturnal baseline impedance and acid exposure time from 24-hour pH-impedance monitoring.

Esophageal baseline impedance (BI) acquired during esophageal contraction (contractile segment impedance [CSI]) is proposed to improve BI accuracy in gastroesophageal reflux disease (GERD). We evaluated associations between CSI and conventional and novel GERD metrics. We analyzed high-resolution impedance manometry (HRIM) and ambulatory pH-impedance studies from 51 patients (58.6 ± 1.5years; 26% F) with GERD symptoms studied off antisecretory therapy. Patients with achalasia or absent contractility were excluded. CSI (averaged across 10 swallows) and BI-HRIM (from the resting landmark phase) were acquired from the distal impedance sensors (distal sensor and 5cm above the lower esophageal sphincter). Acid exposure time (AET) and mean nocturnal baseline impedance (MNBI) were calculated. Associations between CSI, BI-HRIM, MNBI, and AET were evaluated using correlation (Pearson) and receiver operating characteristic (ROC) analysis. Presenting symptoms included heartburn (67%), regurgitation (12%), cough (12%), and chest pain (10%). CSI-distal and CSI-5 each correlated with BI-HRIM, AET, and distal MNBI. Associations with AET were numerically stronger for CSI-distal (r = -0.46) and BI-HRIM-distal (r = -0.44) than CSI-5 (r = -0.33), BI-HRIM-5 (r = -0.28), or distal MNBI (r < -0.36). When compared to AET <4%, patients with AET >6% had significantly lower CSI-distal and BI-HRIM-distal values but not CSI-5, BI-HRIM-5, or MNBI. ROC areas under the curve for AET >6% were numerically higher for CSI-distal (0.81) than BI-HRIM-distal (0.77), distal MNBI (0.68-0.75), CSI-5 (0.68), or BI-HRIM-5 (0.68). CSI from HRIM studies inversely correlates with pathologic AET and has potential to augment the evaluation of GERD.

Distal Esophageal Impedance Measured by High-resolution Esophageal Manometry With Impedance Suggests the Presence of Barrett's Esophagus.

Background/AimsBarrett’s esophagus (BE) is characterized by intestinal metaplasia in the distal esophagus. The aims of this study are to: (1) Compare baseline distal esophageal impedance (DEI) using high-resolution esophageal manometry with impedance (HREMI) in patients with BE, esophagitis, and healthy volunteers and (2) Correlate length of low impedance on HREMI in patients with BE to the length of endoscopic BE.MethodsPatients with BE or esophagitis who underwent HREMI were included. Ten volunteers had HREMI. Baseline DEI was calculated from HREMI using the landmark segment. In patients with BE, the impedance was plotted to measure the extent of plotted low impedance (PLI) and visual low impedance (VLI). Lengths of VLI and PLI were correlated to endoscopic length of BE by Prague score.ResultsForty-five patients were included (16 BE; 19 esophagitis; 10 volunteers). BE patients had lower baseline DEI at the first, second, and third sensors above the lower esophageal sphincter (mean ± SEM: 1.37 ± 0.45, 0.97 ± 0.27, and 0.81 ± 0.20) compared to volunteers (8.73 ± 0.60, 8.20 ± 0.73, and 6.94 ± 0.99; P < 0.001). Baseline DEI was lower in BE than esophagitis patients (2.98 ± 0.65, 2.49 ± 0.56, and 2.01 ± 0.51) at the first, second, and third sensors (P < 0.052 for second and third sensors); ie, BE < esophagitis < controls. PLI and VLI had a stronger correlation to circumferential score (r2 = 0.84 and 0.83) than maximal score (r2 = 0.76 and 0.68).ConclusionsBaseline DEI is lower in BE compared with esophagitis and healthy volunteers. The length of low impedance correlates to the endoscopic extent of BE. Thus, impedance values during HREMI may help suggest the presence and extent of BE or esophagitis.

Mucosal impedance for esophageal disease: evaluating the evidence.

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

Impedance in the evaluation of the esophagus.

The aim of this paper is to review esophageal electrical impedance technologies and to discuss the use of these technologies for physiological measurements, diagnostics, and therapy of esophageal disease. In order to develop a better understanding of the pathophysiology of and improve the diagnosis of esophageal disorders, such as gastroesophageal reflux disease (GERD) and achalasia, several new diagnostic tests, including intraluminal impedance, esophageal mucosal impedance, and the functional luminal imaging probe, have been developed. These technologies have proven valuable for assessment of the esophagus in recent years. They provide information on esophageal flow properties, mucosal integrity, lumen shape, and distensibility in esophageal disorders, in particular for GERD and achalasia. Despite their promise and novel clinical studies, the potential of these technologies has been far from realized. New multidisciplinary approaches will contribute to our understanding and interpretation of esophageal impedance data and disease mechanisms.

Duration of adhesion of swallowed alginates to distal oesophageal mucosa: implications for topical therapy of oesophageal diseases.

We have previously shown, ex vivo, that alginate solutions can have a topical protective effect on oesophageal mucosal biopsies exposed to simulated gastric juice. Oesophageal mucosal impedance can measure the duration of mucosal adherence of ionic solutions since the impedance drops when the solution is present, and rises to baseline as the solution clears. To investigate the in vivo duration of adhesion of swallowed alginate solution to distal oesophageal mucosa. We studied 20 healthy volunteers and 10 patients with heartburn. A pH-impedance catheter was inserted, and baseline distal channel oesophageal impedance measured. Healthy volunteers received 10mL of either sodium alginate (Gaviscon Advance), Gaviscon placebo (no alginate) or viscous slurry (saline mixed with sucralose), given in a randomised, single-blinded order over three visits. Patients received either sodium alginate or placebo on two visits. Initial impedance drop was measured, then 1-minute mean impedance was measured each minute until ≥75% recovery to baseline. In healthy volunteers, sodium alginate adhered to the oesophageal mucosa for longer than placebo or viscous slurry (10.4 [8.7] minutes vs 1.1 [1.6] vs 3.6 [4.0], P<0.01). In patients, sodium alginate adhered to the oesophageal mucosa for longer than placebo (9.0 (5.4) vs 3.7 (4.1), P<0.01). Sodium alginate solution adhered to the oesophageal mucosa for significantly longer than placebo or viscous slurry. This demonstrates that alginates could confer a protective benefit due to mucoadhesion and can be a basis for further development of topical protectants and for topical drug delivery in oesophageal disease.

Esophageal Function Abnormalities in Patients With Barrett's Esophagus.

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

Characterization of Upper Gastrointestinal Motility in Infants With Persistent Distress and Non-IgE-mediated Cow's Milk Protein Allergy.

Persistent crying in infancy is common and may be associated with gastroesophageal reflux disease (GERD) and/or non-IgE-mediated cow's milk protein allergy (CMPA). We aimed to document upper gastrointestinal motility events in infants with CMPA and compare these to findings in infants with functional GERD. Infants aged 2 to 26 weeks with persistent crying, GERD symptoms and possible CMPA were included. Symptoms were recorded by 48-hour cry-fuss chart and validated reflux questionnaire (infant GERD questionnaire [IGERDQ]). Infants underwent a blinded milk elimination-challenge sequence to diagnose CMPA. GERD parameters and mucosal integrity were assessed by 24-hour pH-impedance monitoring before and after cow's milk protein (CMP) elimination. C-octanoate breath testing for gastric emptying dynamics, dual-sugar intestinal permeability, fecal calprotectin, and serum vitamin D were also measured. Fifty infants (mean age 13 ± 7 weeks; 27 boys) were enrolled. On the basis of CMP elimination-challenge outcomes, 14 (28%) were categorized as non-IgE-mediated CMPA, and 17 (34%) were not allergic to milk; 12 infants with equivocal findings, and 7 with incomplete data were excluded. There were no baseline differences in GERD parameters between infants with and without CMPA. In the CMPA group, CMP elimination resulted in a significant reduction in reflux symptoms, esophageal acid exposure (reflux index), acid clearance time, and an increase in esophageal mucosal impedance. In infants with persistent crying, upper gastrointestinal motility parameters did not reliably differentiate between non-IgE-mediated CMPA and functional GERD. In the group with non-IgE-mediated CMPA, elimination of CMP significantly improved GERD symptoms, esophageal peristaltic function, and mucosal integrity.

Reflux Symptoms in Gastroparesis: Correlation With Gastroparesis Symptoms, Gastric Emptying, and Esophageal Function Testing.

The goal of this study was to determine the relationship of reflux with gastroparesis (Gp), looking both at symptoms and objective testing. Gp patients often experience gastroesophageal reflux symptoms. How the severity of reflux correlates with the severity of Gp is not known. Patients referred to our academic center with symptoms of Gp completed the Patient Assessment of Upper Gastrointestinal Symptoms, Hospital Anxiety and Depression Scale, and Patient Health Questionnaire (PHQ)-15. They underwent 4-hour gastric emptying scintigraphy; and, if indicated, high-resolution esophageal manometry and esophageal pH impedance (EpHI). Of 755 patients from July 2013 to May 2018, 432 had Gp with Gastroparesis Cardinal Symptom Index (GCSI) total score of 3.2±0.1 (mean±SEM) and heartburn/regurgitation subscore of 2.0±0.1. A fourth (27.1%) of all Gp patients had moderate to very severe heartburn/regurgitation symptoms. Heartburn/regurgitation subscore had strong correlation with GSCI total score (r=0.56, P<0.01), and weak correlation with 4-hour gastric retention (r=0.11, P=0.02). In total, 103 Gp patients underwent EpHI monitoring; time esophageal pH<4 had no correlation with heartburn/regurgitation subscore. Less than half (41.7%) of the patients undergoing EpHI had gastroesophageal reflux disease by EpHI. Gp patients with gastroesophageal reflux disease had more severe 4-hour gastric retention, and more frequently had decreased lower esophageal sphincter resting pressure and esophageal motility disorders. Heartburn/regurgitation subscore had moderate correlation with somatic symptoms, and weak correlations with anxiety and depression. The severity of reflux symptoms in Gp has strong correlation with GCSI total score, weak correlation with gastric retention, and no correlation with esophageal pH monitoring.

Perioperative gastroesophageal regurgitation in patients with elevated abdominal pressure with nasogastric tubes? A simulation model based on esophageal multichannel intraluminal impedance and pH monitoring

Increased abdominal pressure is common in obese patients and predisposes them to gastroesophageal regurgitation (GER). To drain GER and prevent aspiration, nasogastric (NG) tubes are frequently inserted in obese patients undergoing general anesthesia. However, whether gastric drainage actually decreases the occurrence of GER remains to be elucidated. In this study, increased abdominal pressure was simulated with laparoscopic pneumoperitoneum and Trendelenburg (LPT) positioning, while the retained NG tube was replaced by a pre-inserted esophageal multichannel intraluminal and pH (MII-pH) monitoring. Fifteen patients undergoing elective gynecologic laparoscopy were enrolled in this study. Thirteen patients (86%) developed GER while in the LPT position. With the high occurrence of GER, pre-inserted NG tubes under general anesthesia are not likely to be protective in obese patients.

A study of proximal esophageal baseline impedance in identifying and predicting laryngopharyngeal reflux.

Laryngopharyngeal reflux (LPR) is caused by the reflux of gastric contents beyond the esophagus into the larynx and pharynx. However, upper esophageal sphincter (UES) motility and proximal esophagus reflux parameters are poorly studied. This study aims to explore the characteristics of UES motility and reflux parameter among LPR patients. Patients with laryngopharyngeal symptoms only (L), patients with laryngopharyngeal symptoms and typical esophageal symptoms (L+E), patients with typical esophageal symptoms only (E), and healthy controls (H) were retrospectively included. Physiological profiles were studied and compared among groups using both high-resolution manometry and pH-impedance monitoring, including UES basal pressure, residual pressure, relaxation duration time, recovery time, the time to nadir pressure, UES length, proximal contractile integral, and proximal mean nocturnal baseline impedance (MNBI). Patients' symptom outcomes were also analyzed. A total of 242 patients were included. Proximal MNBI was significantly lower in patients with both laryngopharyngeal and esophageal symptoms (17cm above low esophageal sphincter [LES]: L vs L+E vs E vs H=3689.7 vs 2500.0 vs 3073.0 vs 3996.0; 15cm above LES: L vs L+E vs E vs H=3155.9 vs 2553.4 vs 3198.9 vs 2985.2; P<0.001). Patients responded to proton pump inhibitor treatment also had lower proximal MNBI than those who did not (17cm above LES: 1834.0 vs 3500.0; 15cm above LES: 1946.5 vs 3432.6; P<0.001). Decreased proximal MNBI can not only identify LPR patients but also predict patients' symptom outcomes.

Pressure-impedance analysis: Assist the diagnosis and classification of ineffective esophageal motility disorder.

We elucidated the clinical significance of distal contractile integral-to-esophageal impedance integral (EII) ratio (DCIIR) in ineffective esophageal motility (IEM) adult patients. We recruited 101 patients with IEM (48.38±1.58years) and 42 matched healthy volunteers (44.28±1.85years) in this case-control study. All subjects underwent esophageal high-resolution impedance manometry from October 2014 to May 2018. The diagnosis of IEM was based on the Chicago Classification version 3.0. The EII, EII ratio, and DCIIR were analyzed by matlab software. The EII, EII ratio, and DCIIR calculated at an impedance threshold of 1500Ω (EII1500, EII ratio1500, and DCIIR1500, respectively) were significantly lower in the IEM group than in healthy controls (P<0.0001, <0.0001, and <0.0001, respectively). Receiver operating characteristic analysis showed that DCIIR1500<0.008mmHg/Ω, EII1500>71000Ω.s.cm, and EII ratio1500 >0.43 were all predictive of IEM. Only DCIIR1500<0.008mmHg/Ω remained significant in diagnosing IEM in the multivariate logistic regression analysis (odds ratio=72.13, P<0.001). The DCIIR1500 is negatively correlated with Eckardt score and the Reflux Disease Questionnaire (correlation coefficient=-0.2844 and -0.3136; P=0.0006 and 0.0002, respectively). Receiver operating characteristic analysis further showed that a DCIIR1500 cut-off of 0.002mmHg/Ω achieved the best differentiation between the IEM-alternans and IEM-persistens subtypes among IEM patients (P<0.001). The novel pressure-impedance parameter of high-resolution impedance manometry, DCIIR1500, may assist in the diagnosis and classification of IEM and correlated with clinical symptoms.

Rumination Syndrome: Recognition and Treatment.

The purpose of this paper is to discuss current diagnostic and treatments of rumination. Rumination is often underdiagnosed or misdiagnosed in adults, especially when symptoms suggest regurgitation rather than vomiting accompanied by re-chewing and re-swallowing and should be included in the differential diagnosis. It is primarily diagnosed clinically by ROME-IV or DSM-5. That rumination can be re-affirmed by characteristic patterns on objective testing such as high-resolution esophageal manometry and 24-h pH impedance testing. However, although gastroduodenal manometry and EMG are helpful, these tests are slowly losing interest given their technical nature of data gathering, time consumption, cost burden, and patient discomfort. Rumination is primarily diagnosed clinically by ROME-IV or DSM-5 in addition to high-resolution esophageal manometry and 24-h pH impedance. Management is challenging and usually a combination of behavioral, pharmacological, and rarely surgical treatment. Recent data demonstrate that the combination of behavioral techniques such as diaphragmatic breathing exercises and/or with baclofen has promising results. Further research is necessary to further define objective criteria for diagnosis and other therapeutic modalities for treatment.

Role of Esophageal Mean Nocturnal Baseline Impedance and Post-reflux Swallow-induced Peristaltic Wave Index in Discriminating Chinese Patients With Heartburn.

Background/AimsRecently, esophageal mean nocturnal baseline impedance (MNBI) and post-reflux swallow-induced peristaltic wave (PSPW) index have been proposed, which can increase the diagnostic role of multichannel intraluminal impedance and pH recording (MII/pH) for differentiating patients with heartburn. Therefore, our aim is to investigate the role of esophageal proximal MNBI, distal MNBI, and PSPW index in differentiating Chinese patients with heartburn.MethodsPatients with heartburn from the Beijing Anzhen Hospital, who underwent upper gastrointestinal endoscopy and 24-hour MII/pH, were enrolled in this study.ResultsIn all, 24 erosive esophagitis (EE), 46 non-erosive reflux disease (NERD), 52 reflux hypersensitivity (RH), and 78 functional heartburn (FH) patients were recruited. The respective median values for the EE, NERD, RH, and FH groups were as follows: proximal MNBI 1858.0, 2147.5, 2374.3, and 2329.0 Ω (P = 0.053); distal MNBI 1243.4, 1506.5, 2451.2, and 2477.3 Ω (P < 0.001); and PSPWI 15.0%, 25.0%, 25.0%, and 45.0% (P < 0.001). Spearman correlation analysis showed that distal MNBI and PSPW index were significantly negatively correlated with acid and bolus exposure time and acid reflux events. Receiver operating characteristic analyses showed that distal MNBI and PSPW index significantly discriminated FH from EE, NERD, and RH (P < 0.001), with cut-off values of 1890.6 Ω and 27.5% and areas under the curve of 0.721 and 0.779, respectively.ConclusionEsophageal distal MNBI and PSPW index could increase the diagnostic role of MII/pH, especially for differentiating Chinese patients with heartburn.

373 Routine EGD Has Minimal Impact on Refractory GERD Management

INTRODUCTION: Routine diagnostic esophagogastroduodenoscopy (EGD) is recommended for refractory gastro-esophageal reflux disease (GERD) symptoms despite lack of evidence that it impacts management or outcomes. This study aims to determine if diagnostic EGD impacts management in patients with refractory GERD compared to esophageal manometry, pH testing and intra-luminal impedance. METHODS: We performed an observational study of patients with refractory GERD who underwent EGD from 2013 to 2018 at a tertiary hospital. Among 1,213 patients with GERD, we strictly excluded patients with alarm features such as dysphagia, dyspepsia; history of gastroesophageal surgery, or EGD done for other diagnostic procedures, and identified 339 patients who underwent EGD solely for persistent reflux symptoms. We then identified those who had esophageal manometry or pH-impedance studies for further evaluation of GERD, as well as if the findings of these tests resulted in a change in management (medication change or de-escalation, referral for Nissen fundoplication, etc). RESULTS: Among 339 patients with refractory GERD, 80.5% of patients were taking PPIs prior to and/or at the time of EGD. The majority of patients had completely normal (163/339, 48.1%) or solely benign or incidental findings (106/339, 31.3%) on EGD. Only 10.6% of patients had esophageal manometry or pH-impedance studies for refractory reflux symptoms, of those, 6.2% followed EGD and only 7 patients had these studies after a completely normal EGD. The majority of patients undergoing manometry had normal studies or minor abnormalities (23/32, 71.8%). All patients who had been ordered for intraluminal impedance or 24 hr pH testing alone could not tolerate the procedure. Six of 15 patients (40%) undergoing 24 hr pH-impedance testing had findings leading to a change in management. Undergoing pH-impedance testing after EGD was associated with a change in management (OR 7.33, P = 0.018). PPI use was not associated DeMeester score or with results of manometry, impedance, or pH testing. CONCLUSION: Most patients who underwent EGD for refractory GERD symptoms alone did not have pathological findings prompting a change in management. There were no demographic variables that predicted pathologic findings on EGD. Very few patients underwent subsequent or concomitant esophageal manometry, impedance or pH testing. pH-impedance after EGD was associated with a change in management, and may be a better first step in evaluating patients with refractory GERD symptoms, than EGD.

382 Esophageal Mucosal Impedance Measurement During Endoscopy: A New Approach to Diagnosis and Confirmation of Complete Remission of Intestinal Metaplasia Following Radiofrequency Ablation in Barrett’s Esophagus

INTRODUCTION: Mucosal impedance (MI), measured with a specialized balloon catheter at the time of upper endoscopy reveals a distinct pattern within the esophagus in patients with eosinophilic esophagitis and GERD. This novel technology may also be able to identify a unique profile in Barrett’s esophagus (BE) and confirm Endoscopic Complete Remission of Intestinal Metaplasia (ECRIM) following Radiofrequency energy ablation (RFA). AIM: Explore utility of MI in identification of BE and confirmation of ECRIM following RFA. METHODS: Patients (pts) with endoscopic and biopsy proven BE, most dysplasia undergoing RFA were prospectively enrolled. All were maintained on BID PPI. EGD noted top of gastric folds, SCJ, Prague criteria, hernia size and presence of nodules. Pts with nodular disease were excluded. RFA was performed per standard protocol and repeated until ECRIM achieved. Measurements were obtained with an MI balloon (Diversatek Healthcare, CO) 10 cm x 5 mm with two axial arrays of 10 sensors, throughout the entire BE segment and 5 cm above at pre-ablation EGD and following achieving ECRIM. At ECRIM endoscopic surveillance biopsies (q 1 cm; 4 quadrant) and WATS brushings were obtained to confirm CRIM. RESULTS: 16 pts 11M/5F, ages 26-71 years, all Caucasian were enrolled. BE length from 1-15 cm. (adenoca 1, LGD 5, HGD 5, indefinite1, Non dysplastic 4. To date, 7 pts have been studied prior to the initial RFA ablation and at ECRIM. 2 pts were studied only at end of RFA with ECRIM. 7 are in active treatment. MI measured within the BE segment ranged from 350-980 ohms pre RFA. (Normal &gt;2500, EoE, GERD &gt;1000). Post RFA MI measurements ranged from 1800- &gt;5000 ohms. 5/7 pts that achieved ECRIM had normalization of the MI pattern visualized (all values &gt;2500). The 2 pts that did not achieve normalization of the MI pattern demonstrated MI values consistent with inflammation in squamous tissue but no values suggestive of BE. Pathology confirmed absence of IM in all 9 pts. CONCLUSION/SUMMARY: 1) BE exhibits MI consistently &lt; 500 ohms and always below 1000 ohms, a unique MI profile not evident in GERD or EoE. 2) In pts who achieved ECRIM and biopsy and WATS proven CRIM following RFA ablation, the neosquamous esophageal mucosa exhibits a MI pattern similar to normal native squamous epithelium. Balloon catheter MI measurements can reliably identify BE epithelium and may be a valuable tool in assessment of post-RFA reversion to neosquamous epithielium and therefore successful BE ablation.

Gastroesophageal reflux in cystic fibrosis across the age spectrum.

Scientific advances have improved longevity in cystic fibrosis (CF) patients and many of these patients can expect to experience age-related gastrointestinal co-morbidities. We aimed to assess the extent to which age might impact gastroesophageal reflux (GER) in patients with CF. Our esophageal pH-multichannel intraluminal impedance monitoring database was searched for tracings belonging to CF patients ≥2 years old without prior fundoplication and not taking anti-reflux medications immediately prior (within 7 days) and during the study. Tracings were retrospectively analyzed; Impedance and pH variables were evaluated with respect to age and pulmonary function. Twenty-eight patients were enrolled; 16 children (3.1-17.7 years) and 12 adults (18.2-48.9 years). Among pH probe parameters, correlation analysis showed DeMeester score (P=0.011) and number of acid reflux events lasting >5 minutes (P=0.047) to be significantly correlated with age. Age was not significantly correlated with any of the impedance parameters. Age was negatively correlated with baseline impedance (BI) in the distal esophagus (r=-0.424, P=0.023) and BI was negatively correlated with several pH parameters, including reflux index (r=-0.553, P=0.002), number of total acid reflux events (r=-0.576, P=0.001), number of acid reflux events lasting >5 minutes (r=-0.534, P=0.003), and DeMeester score (r=-0.510, P=0.006). Pulmonary function (percent predicted forced expiratory volume in one minute; ppFEV1) was negatively correlated with age (r=-0.494, P=0.0007). The interaction of age and ppFEV1 and any of the reflux parameters, however, was not significant (P>0.05); the strongest evidence for an interaction was found for the number of acid reflux events reaching the proximal esophagus, but this interaction still did not reach statistical significance (P=0.070). In a small cohort, we found evidence that age may be associated with increased acid exposure and that both age and increased acid exposure are associated with reduced BI in the distal esophagus. The negative relationship between pulmonary function and age in our cohort is not related to GER. This pilot study supports the need for esophageal assessment and treatment of GER as standard components of clinical care for an aging CF population.

Detecting intraoperative gastric regurgitation by using preattached esophageal multichannel intraluminal impedance and pH monitoring on a solid-state manometry: a case series study.

Adequate barrier pressure (BrP), calculated by subtracting intragastric pressure (IGP) from lower esophageal sphincter pressure (LESP), is believed to prevent gastroesophageal regurgitation (GER). However, the occurrence of intraoperative GER, the height and acidity it reached, have rarely been demonstrated simultaneously along with BrP. In this study, we developed preattached multichannel intraluminal impedance monitoring combined with pH-metry (the gold standard for detecting both height and acidity) on a solid-state manometry to continuously detect intraoperative GER as well as BrP changes. We used this system to record LESP, IGP, and changes in impedance through multichannel sensors and pH in patients receiving elective gynecological laparoscopy with laparoscopic pneumoperitoneum and Trendelenburg (LPT) positioning. Changes in BrP were analyzed at three time points (T1: before LPT; T2: during LPT when LESP reached its peak; and T3: after the offset of LPT). Our results indicated that this preattached experimental setup is feasible for intraoperative applications. GER was not detected in our patients throughout LPT. The mean LESP at T2 (23.22mmHg) was significantly higher than at T1 (13.23mmHg), but comparable to that at T3 (18.91mmHg). The mean IGP (3.24mmHg) at T2 was significantly higher than at T1 and T3 (- 6.10 and - 2.25mmHg, respectively). The mean BrP scores were comparable from T1 to T3 (T1: 19.34mmHg; T2: 19.98mmHg; T3: 21.16mmHg). Based on our results, the proposed setup is helpful for intraoperative monitoring and management of patients at high risk of GER.