Distal Impedance Research Articles

Esophageal Baseline Impedance is Associated with Laryngopharyngeal Reflux and Treatment Response.

To evaluate the efficacy of distal esophageal mean nocturnal baseline impedance (MNBI), a general marker of esophageal mucosal barrier integrity, in predicting laryngopharyngeal reflux (LPR) and symptomatic response to acid reflux therapy. This retrospective study analyzed 173 patients who presented with symptoms of laryngopharyngeal reflux and underwent 24-h multichannel intraluminal impedance-pH (MII-pH) testing. Mean nocturnal baseline impedance values were calculated and assessed for their association and ability to predict LPR symptoms, MII-pH results, treatment response, and other markers of LPR. Notably, 153 of the 173 patients were tested off acid suppression medication and included in statistical analysis. Based on the MII-pH probe data, 108 (71%) patients had LPR, 8 (5%) had gastroesophageal reflux disease (GERD), and 37 (24%) were without pathologic reflux. Distal esophageal MNBI of LPR patients was significantly lower in LPR patients than patients with negative studies (1332 ± 94.8 vs. 2158 ± 173.5, p = 0.001). Among 118 patients who trialed antireflux therapy, a distal esophageal MNBI cutoff value of <1580 Ω was an independent predictor of treatment response (OR = 4.148 [1.877-9.189]). This value better predicted improvement with antireflux therapy for LPR than other objective MII-pH probe data, which were not independent predictors of treatment response. Distal esophageal MNBI values may have value in the diagnosis of LPR and potentially predict medication responsiveness in LPR patients. 3 Laryngoscope, 134:4071-4077, 2024.

Comparison of direct effects of rice-thickened formula vs routine feeds on symptoms and gastroesophageal reflux indices: A crossover cohort study.

We compared the direct effects of routine vs rice-thickened formula on 24-h pH-impedance and symptom characteristics and then examined if dietary effects were modified by acid reflux index severity in infants. Forty infants under consideration for gastroesophageal reflux disease and therapies were evaluated at 43 ± 1 weeks postmenstrual age. Each infant was equally fed routine diet and thickened formula during evaluations. Postprandial sessions were analyzed for acid reflux index, reflux events, clearance times, distal baseline impedance, and symptoms. Thickened formula has no effect (P ≥ 0.05) on acid reflux events' characteristics or overall symptom frequency. However, refluxate height and frequency of weakly acidic events and cough were decreased (P < 0.05). Prolonged bolus clearance and a decrease in distal baseline impedance were noted with thickened feeds (vs routine feeds) when acid reflux index was >7 (P < 0.05). Our pH-impedance testing protocol identifies direct effects of potential therapies at the point of care. Acutely, thickened formula does not impact acid-specific reflux indices but decreases full-column reflux and cough reflexes. In those with an acid reflux index of >7, thickened formula prolongs the distal esophageal bolus clearance (the mechanisms of which are uncertain). Clinical trials are needed to clarify objective indications and therapeutic use of thickened formulas for infants with gastroesophageal reflux disease, along with short- and long-term side effects.

Worse glycemic control is associated with an impaired arterial energy transfer pattern in elderly with diabetes

Abstract Background Worse glycaemic control is known to exacerbate endothelial insult, increasing macro- and microvascular complication risks in diabetes. Impaired intracranial haemodynamics have been frequently reported in patients with diabetes alongside with malperfusion causing structural abnormalities, and poor cognitive and cortical functionality (1-2).Assessment of the alterations in energy transfer characteristics derived from hemodynamic signals may provide novel mechanistic information about how worse glycaemic control may affect cerebrovascular perfusion. Wave reflection index(WRI) is a previously proposed measure of arterial energy transfer efficiency which reflects distal impedance mismatch(3-4). Purpose We aim to interrogate potential relationship between a worse glycaemic control and a less efficient arterial energy transfer, which could enhance our understanding of the cerebrovascular-cortical functional coupling on a mechanistic basis in elderly with diabetes. Methods Left middle cerebral artery wave intensity (WI) was computed with arterial blood pressure and flow velocity (transcranial Doppler) signal as previously described (WI = (dP/dt)*(dU/dt)) (Figure 1). Standard statistical tests were used to interrogate the relationship between glycated haemoglobin levels (HbA1c) and WI parameters. Results In 36 patients with diabetes mellitus type-2 (DM2) (mean age = 65.7 ± 8.8 years), backward compression wave intensity (BCWI) and wave reflection ratio (WRI= BCWI/FCWI) were significantly correlated with HbA1c levels before (rBCWI: 0.409 pBCWI:0.013; rWRI:0.345 pWRI:0.040) and after (rBCWI: 0.410 pBCWI:0.018, rWRI:0.351 pWRI:0.045) adjusting for age, sex and mean arterial pressure (Figure 2). Conclusion(s) In elderly patient with DM2, higher HbA1c values indicating worse glycaemic control are significantly correlated with altered cerebrovascular energy transfer characteristics as assessed by MCA wave intensity analysis. Continuous relationship between worse glycaemic control and higher wave reflection index (a measure of less efficient energy transfer in arterial system and distal impedance mismatch) may imply that the use of energy transfer related indices alongside with conventional hemodynamic indices may help providing a more comprehensive pathophysiological understanding about how cardiovascular risk factors interfere with perfusion.Computation of Wave IntensityMain Results

Impact of esophageal mucosal permeability markers on provocation-induced esophageal reflexes in high-risk infants.

Esophageal distal baseline impedance (DBI) is an indicator of mucosal integrity; lower values suggest increased permeability. Aims were to characterize the (1) effect of DBI category (<900 Ω, 900–2000 Ω, and >2000 Ω) on sensory‐motor characteristics of mid‐esophageal provocation‐induced motility reflexes, and (2) clinical outcomes among high‐risk human infants evaluated for gastroesophageal reflux disease. Symptomatic infants (N = 49, 41 ± 3 weeks postmenstrual age) underwent pH‐impedance testing to characterize acid reflux index (ARI) and DBI, and pharyngo‐esophageal manometry to examine upper esophageal sphincter (UES), peristaltic, and lower esophageal sphincter (LES) functions. Sensory‐motor response characteristics included response threshold (ml), occurrence (%), latency (s), duration (s), and magnitude (mmHg) upon mid‐esophageal stimulations (0.1–2.0 ml of air, water, and apple juice). Motility and clinical outcomes were compared among DBI groups. In infants with DBI <900 Ω and 900–2000 Ω (vs. >2000 Ω): (a) Long‐term feeding milestones did not differ (p > 0.05); (b) complete peristaltic propagation decreased in 900–2000 Ω (p < 0.05), polymorphic waveforms increased in <900 Ω and 900–2000 Ω (p < 0.05); (c) media effects were noted with liquids (vs. air) wherein UES and esophageal contractility were prolonged in <900 Ω and 900–2000 Ω (p < 0.05), and esophageal sensitivity heightened for <900 Ω with water and for 900–2000 Ω with air (both p < 0.05). ARI was not correlated with DBI in infants with chronic lung disease (r = 0.05, p = 0.82). We conclude that pharyngo‐esophageal motility sensory‐motor characteristics in infants are modified by DBI category. These preliminary findings pave‐the‐way for further physiological testing in convalescing high‐risk infants to ascertain potential mechanisms of airway‐digestive reflex interactions and symptom generation, which may lead to targeted therapies.

Symptom Scores and pH-Impedance: Secondary Analysis of a Randomized Controlled Trial in Infants Treated for Gastroesophageal Reflux.

BACKGROUND AND AIMS:To evaluate and compare gastro-esophageal reflux (GER) symptom scores with pH-impedance and test the effects of acid-suppressive medications with or without feeding modifications on pH-impedance in high-risk infants.METHODS:Infant Gastroesophageal Reflux Questionnaire Revised (I-GERQ-R) and 24-hour pH-impedance data were analyzed from 94 infants evaluated in a tertiary care setting for GER disease. Longitudinal data from 40 infants that received randomized GER therapy (proton pump inhibitor [PPI] with or without feeding modifications) for 4 weeks followed by 1-week washout were analyzed. Relationships between I-GERQ-R and pH-impedance metrics (acid reflux index, acid and bolus GER events, distal baseline impedance, and symptoms) were examined and effects of treatments compared.RESULTS:(A) Correlations between I-GERQ-R and pH-impedance metrics were weak. (B) I-GERQ-R sensitivity, specificity, and positive predictive values were suboptimal when correlated with pH-impedance metrics. I-GERQ-R negative predictive value (NPV) was high for acid symptom–association probability (NPV = 84%) and distal baseline impedence (NPV = 86%) thresholds. (C) PPI with feeding modifications (vs PPI alone) did not alter pH-impedance metrics or symptom scores (P > .05); however, bolus clearance metrics worsened for both treatment groups (P < .05).CONCLUSIONS:In high-risk infants (1) I-GERQ-R may be a helpful clinical screening tool to exclude acid-GER disease diagnosis and minimize unnecessary acid-suppressive treatment, but further testing is needed for diagnosis. (2) Acid-suppressive therapy with feeding modifications has no effect on symptom scores or pH-impedance metrics. Clearance of refluxate worsened despite PPI therapy, which may signal development of pharyngoesophageal dysmotility and persistence of symptoms. (3) Placebo-controlled trials are needed in high-risk infants with objective pH-impedance criteria to determine efficacy, safety, and underlying mechanisms. Clinicaltrials.gov ID: NCT02486263.

A Multichannel Intraluminal Impedance Gastroesophageal Reflux Characterization Algorithm Based On Sparse Representation.

Gastroesophageal reflux disease (GERD) is a common digestive disorder with troublesome symptoms that has been affected millions of people worldwide. Multichannel Intraluminal Impedance-pH (MII-pH) monitoring is a recently developed technique, which is currently considered as the gold standard for the diagnosis of GERD. In this paper, we address the problem of characterizing gastroesophageal reflux events in MII signals. A GER detection algorithm has been developed based on the sparse representation of local segments. Two dictionaries are trained using the online dictionary learning approach from the distal impedance data of selected patches of GER and no specific patterns intervals. A classifier is then designed based on the lp-norm of dictionary approximations. Next, a preliminary permutation mask is obtained from the classification results of patches, which is then used in post-processing procedure to investigate the exact timings of GERs at all impedance sites. Our algorithm was tested on 33 MII episodes, resulting a sensitivity of 96.97% and a positive predictive value of 94.12%.

Impedance plethysmography-based method in the assessment of subclinical atherosclerosis

Background and aimsThe aim of this study was to examine an association of individual and combined pulse waveform parameters derived from bioimpedance measurements, that is pulse waves from a distal impedance plethysmographic (IPG), a whole-body impedance cardiographic (ICG) and transformed distal impedance plethysmographic (tIPG) signals, with markers of subclinical atherosclerosis, i.e. carotid intima-media thickness (cIMT), brachial artery flow-mediated dilation (FMD) and carotid artery distensibility (Cdist). The level of the association was also compared for arterial pulse wave velocity (PWV) and cIMT, FMD, and Cdist. MethodsIPG, ICG, tIPG signals were measured from 1741 Finnish adults aged 30–45 years. The association between pulse wave parameters and cIMT, FMD and Cdist was studied using bootstrapped stepwise Akaike's Information Criterion method resulting in selection of parameters other than PWV, i.e. parameters having stronger association with cIMT, FMD and Cdist than PWV, in the model. Then risk scores were calculated from the selected pulse wave parameters and their association between cIMT, FMD and Cdist was studied with multivariable linear regression analysis. ResultsThe risk score was found to be the third strongest predictor of subclinical atherosclerosis as indicated by cIMT measurement, the second strongest predictor of FMD and the strongest predictor of Cdist. These findings show that several individual pulse wave parameters were associated more strongly with cIMT, FMD, and Cdist than PWV when adjusted with clinical risk factors. ConclusionsImpedance based pulse waveform analysis provides a useful tool for assessing cardiovascular risk and estimating presence of structural changes in the vasculature.

Evaluation of Gastroesophageal Reflux Disease 1 Year after Esophageal Atresia Repair: Paradigms Lost from a Single Snapshot?

To analyze the findings of both multichannel intraluminal impedance with pH (MII-pH) and endoscopy/histopathology in children with esophageal atresia at age 1year, according to current recommendations for the evaluation of gastroesophageal reflux disease (GERD) in esophageal atresia. We retrospectively reviewed both MII-pH and endoscopy/histopathology performed in 1-year-old children with esophageal atresia who were followed up in accordance with international recommendations. Demographic data and clinical characteristics were also reviewed to investigate factors associated with abnormal GERD investigations. In our study cohort of 48 children with esophageal atresia, microscopic esophagitis was found in 33 (69%) and pathological esophageal acid exposure on MII-pH was detected in 12 (25%). Among baseline variables, only the presence of long-gap esophageal atresia was associated with abnormal MII-pH. Distal baseline impedance was significantly lower in patients with microscopic esophagitis, and it showed a very good diagnostic performance in predicting histological changes. Histological esophagitis is highly prevalent at 1year after esophageal atresia repair, but our results do not support a definitive causative role of acid-induced GERD. Instead, they support the hypothesis that chronic stasis in the dysmotile esophagus might lead to histological changes. MII-pH may be a helpful tool in selecting patients who need closer endoscopic surveillance and/or benefit from acid suppression.

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.

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.

Differentiation of esophageal pH-impedance characteristics classified by the mucosal integrity marker in human neonates

BACKGROUND:In adults, distal baseline impedance (BI) is a determinant of esophageal mucosal integrity with values <900Ω indicating inflammation. Relationships between acid gastroesophageal reflux (GER) and BI in neonates are unclear.METHODS:NICU infants (N=198, 30.4±0.3 weeks gestation) were evaluated at 43±0.4 weeks postmenstrual age using 24-hour pH-impedance. Ten randomly selected one-minute windows during rest from the distal impedance channel (Z6) were averaged. Chi-square, t-tests, and ANOVA were used to compare pH-impedance and symptom characteristics by BI severity (BI<900Ω, BI 900-2000Ω, BI>2000Ω). Regression analysis was used to identify potential contributing factors of BI.RESULTS:In BI<900Ω: 1) pH-impedance characteristics were increased (acid reflux event frequency, duration, and severity, all P<0.05 vs. BI>2000Ω), and 2) positive symptom correlations were noted with bolus (73%) and acid events (55%). Significant predictors of BI included chronological age, acid reflux index, and BPD diagnosis (all P<0.05).CONCLUSIONS:Low BI is associated with prolonged acid exposure, delayed clearance, and greater aerodigestive symptom prevalence, likely associated with inflammation and or increased mucosal permeability. BI>2000Ω likely involves little or no inflammation because acid exposure is minimal. Combination of SAP, pH-impedance metrics and BI along with clarification of dysmotility mechanisms provides the rationale for personalized anti-reflux therapies as needed.

Dual pH Probes Without Proximal Esophageal and Pharyngeal Impedance May Be Deficient in Diagnosing LPR

Laryngopharyngeal reflux (LPR) is commonly treated with empiric acid suppression. More evidence points to pepsin in the pathophysiology of LPR. Previous studies have evaluated esophageal impedance in patients who had previously failed high dose proton pump inhibitor (PPI) using older catheters without proximal esophageal (just under the upper esophageal sphincter) and pharyngeal impedance sensors. The aim of this study was to compare what traditional diagnostic tools, used for esophageal reflux, would detect and diagnose compared with what a combined hypopharyngeal-esophageal MII catheter with dual pH (HEMII-pH) can detect in the esophagus and pharynx in patients with suspected LPR. Forty-two subjects with presumed LPR were referred for HEMII-pH testing. The number of distal and proximal esophageal impedance events, number of pharyngeal impedance events, symptom correlation, and event acidity were recorded. Previous normative values (>1 pharyngeal impedance events every 24 hours) were used to designate what was pathological LPR on HEMII-pH. Forty-two total subjects had pharyngeal impedance sensor data recorded. Twelve (28.6%) of the subjects were tested while taking high-dose PPI therapy. The mean number of proximal esophageal events was 23.3. The mean number of pharyngeal impedance events was 10. Thirty-four subjects (81%) tested positive for pharyngeal reflux. All patients who tested positive using traditional proximal impedance criteria also tested positive using pharyngeal criteria. Of patients who tested negative using traditional criteria, 72% were positive based on pharyngeal criteria. HEMII-pH catheters should be considered in patients with LPR symptoms. Traditional criteria used for diagnosing esophageal reflux may not translate into LPR.

Su1088 - use of High Resolution Esophageal Manometry with Impedance (HREMI) to Detect Distal Esophageal Impedance Changes of Gerd

Su1088 - use of High Resolution Esophageal Manometry with Impedance (HREMI) to Detect Distal Esophageal Impedance Changes of Gerd

Esophageal baseline impedance levels allow the identification of esophageal involvement in patients with systemic sclerosis.

Distal esophageal baseline impedance (BI) levels reflect the esophageal mucosal integrity in reflux disease. Systemic sclerosis (SSc) could potentially affect the integrity of esophageal mucosa and consequently impair distal and proximal BI levels, but data in this regard are lacking. We aimed to prospectively investigate and compare BI levels among non-erosive reflux disease (NERD), SSc patients, and healthy controls (HCs). Consecutive patients with reflux symptoms and well-defined diagnosis of SSc underwent upper endoscopy and, in case of no lesions encountered, manometry and impedance-pH testing off-therapy. In addition to traditional impedance-pH parameters, BI values at 3, 5, 7, and 17cm above the lower esophageal sphincter were calculated. Fifty-two patients with NERD, 50 with SSc, and 50 HCs were enrolled. Nineteen (38%) SSc patients and 22 (42%) NERD patients had abnormal acid exposure. In patients with SSc, median BI values were significantly lower than in NERD patients and HCs (p < 0.0001) at 3, 5, and 7cm; there was no difference between HCs and NERD patients at 17cm in the proximal esophagus, whereas a significant difference was observed at 17cm between SSc and NERD as well as HCs (p < 0.01). Distal and proximal BI values in SSc patients were lower than in NERD and HCs, thus we speculated that these findings may be related to the deposition of collagen in the connective tissue. Measurement of BI may be used as an indirect, but simple and accurate marker of esophageal involvement in patients with SSc.

The diagnostic value of 24-hour ambulatory intraesophageal pH-impedance in patients with laryngopharyngeal reflux symptoms comparable with typical symptoms.

The diagnosis of laryngopharyngeal reflux is currently based on a combination of the patient history of multichannel intraluminal impedance and ambulatory pH (MII-pH); however, none of these findings alone is specific for the diagnosis of laryngopharyngeal reflux. We aimed to compare the baseline characteristics and esophageal baseline impedance values between patients with and without laryngopharyngeal reflux symptoms. We retrospectively analyzed data from two groups of patients with laryngopharyngeal reflux according to their reflux finding score (RFS) as scored by ENTs. Control patients were nonerosive reflux disease patients without laryngopharyngeal reflux. All MII-pH parameters and baseline impedance were analyzed from six levels and the proximal and distal baseline impedance and the ratio of the proximal to distal baseline impedance levels was calculated. Altogether 123 patients with laryngopharyngeal reflux and 49 control patients were included. A total of 81 of 123 patients had RFS ≥ 7, and 42 of 123 patients had RFS < 7. Baseline impedance analysis showed that patients with laryngopharyngeal reflux symptoms had significantly lower proximal baseline impedance values (1997 ± 51 vs 2245 ± 109, p < 0.05) than the control group. Additionally, patients with laryngopharyngeal reflux symptoms had a significantly lower proximal-to-distal ratio (1.28 ± 0.05 vs 1.53 ± 0.09, p < 0.05). In the subgroup analysis, patients with RFS < 7 were found to have a significantly lower acid exposure time than either the patients with RFS ≥ 7 (3.85 ± 0.65 vs 8.2 ± 1.52, p < 0.05) or the control group (3.85 ± 0.65 vs 6.1 ± 0.81, p < 0.05). Additionally, patients with RFS ≥ 7 had significantly lower proximal baseline impedance levels than the control group (1970 ± 63 vs 2245 ± 109, p < 0.05). Patients with pathologic laryngopharyngeal reflux symptom scores had lower proximal baseline impedance levels and lower proximal-to-distal ratios, which may reflect the proximal mucosal noxious effect of the refluxate. These results may indicate that laryngopharyngeal reflux symptoms may be due to chronic acid exposure in the proximal segments of the esophagus, and the proximal-to-distal ratio may be used as a new metric for diagnosis.

Su1058 - Distal Esophageal Impedance Measurements During High Resolution Esophageal Manometry with Impedance (HREMI) Predicts Presence and Length of Barrett's Esophagus (BE)

Su1058 - Distal Esophageal Impedance Measurements During High Resolution Esophageal Manometry with Impedance (HREMI) Predicts Presence and Length of Barrett's Esophagus (BE)

Effects of Esophageal Acidification on Troublesome Symptoms: An Approach to Characterize True Acid GERD in Dysphagic Neonates.

To quantify and compare maximal extent (height) of acid reflux events (AREs) on symptom generation in dysphagic neonates. Dysphagic neonates (N=53), born at 30±5.3weeks gestation, underwent 24-hour pH-impedance study for the evaluation of troublesome symptoms purported to be due to gastroesophageal reflux disease (GERD). AREs (pH<4 for >4s) detected by impedance (Z) were categorized by maximal extent as refluxate reaching distal (Z6, Z5), middle (Z4, Z3), or proximal (Z2, Z1) impedance channels. AREs reaching the pH sensor only were categorized as distal. Symptom correlation (%, symptom index, symptom sensitivity index, and symptom associated probability) and temporal characteristics (clearance times) of AREs were analyzed using linear mixed and GEE models comparing height categories presented as mean±SEM, median (IQR), and OR (95% CI). Of the 2003 AREs, 1) distal extent AREs (n=1642) had increased frequency (p<0.05), decreased ACT (p<0.05), and decreased acidity (p<0.05); 2) in middle and proximal AREs, acid clearance was longer than bolus clearance, (p<0.01); and 3) the odds of having cardiorespiratory (cough or sneeze) symptoms are increased with proximal and middle AREs (p<0.05). Most proximal ascent of AREs into middle or proximal esophagus likely activates protective aerodigestive reflexes (peristalsis) or vigilant states to facilitate bolus and chemical clearance. Heightened esophageal sensitivity, acid neutralization delays, or clearance mechanism delays may accentuate multi-systemic troublesome symptoms.

Esophageal mucosal integrity improves after laparoscopic antireflux surgery in children with gastroesophageal reflux disease

BackgroundEsophageal intraluminal baseline impedance reflects the conductivity of the esophageal mucosa and may be an instrument for in vivo evaluation of mucosal integrity in children with gastroesophageal reflux disease (GERD). Laparoscopic antireflux surgery (LARS) is a well-established treatment option for children with proton pump inhibitory (PPI) therapy resistant GERD. The effect of LARS in children on baseline impedance has not been studied in detail. The aim of this study was to evaluate the effect of LARS on baseline impedance in children with GERD.MethodsThis is a prospective, multicenter, nationwide cohort study (Dutch national trial registry: NTR2934) including 25 patients [12 males, median age 6 (range 2–18) years] with PPI-resistant GERD scheduled to undergo LARS. Twenty-four hour multichannel intraluminal impedance pH monitoring (MII-pH monitoring) was performed before and 3 months after LARS. Baseline impedance was evaluated during consecutive 2-h intervals in the 24-h tracings.ResultsLARS reduced acid exposure time from 8.5 % (6.0–16.2 %) to 0.8 % (0.2–2.8 %), p < 0.001. Distal baseline impedance increased after LARS from 2445 Ω (1147–3277 Ω) to 3792 Ω (3087–4700 Ω), p < 0.001. Preoperative baseline impedance strongly correlated with acid exposure time (r −0.76, p < 0.001); however, no association between symptomatic outcome and baseline impedance was identified.ConclusionsLARS significantly increased baseline impedance likely reflecting recovery of mucosal integrity. As the change in baseline impedance was not associated with the clinical outcome of LARS, other factors besides mucosal integrity may contribute to symptom perception in children with GERD.

Esophageal Acid Clearance During Random Swallowing Is Faster in Patients with Barrett's Esophagus Than in Healthy Controls.

Background/AimsImpaired esophageal acid clearance may be a contributing factor in the pathogenesis of Barrett’s esophagus. However, few studies have measured acid clearance as such in these patients. In this explorative, cross-sectional study, we aimed to compare esophageal acid clearance and swallowing rate in patients with Barrett’s esophagus to that in healthy controls.MethodsA total of 26 patients with histology-confirmed Barrett’s esophagus and 12 healthy controls underwent (1) upper endoscopy, (2) an acid clearance test using a pH-impedance probe under controlled conditions including controlled and random swallowing, and (3) an ambulatory pH-impedance measurement.ResultsCompared with controls and when swallowing randomly, patients cleared acid 46% faster (P = 0.008). Furthermore, patients swallowed 60% more frequently (mean swallows/minute: 1.90 ± 0.74 vs 1.19 ± 0.58; P = 0.005), and acid clearance time decreased with greater random swallowing rate (P < 0.001). Swallowing rate increased with lower distal esophageal baseline impedance (P = 0.014). Ambulatory acid exposure was greater in patients (P = 0.033), but clearance times assessed from the ambulatory pH-measurement and acid clearance test were not correlated (all P > 0.3).ConclusionsMore frequent swallowing and thus faster acid clearance in Barrett’s esophagus may constitute a protective reflex due to impaired mucosal integrity and possibly acid hypersensitivity. Despite these reinforced mechanisms, acid clearance ability seems to be overthrown by repeated, retrograde acid reflux, thus resulting in increased esophageal acid exposure and consequently mucosal changes.