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Introduction and Objectives: Analysis of nocturnal basal impedance (IBNM) has been proposed as a way to increase accuracy of GERD diagnosis. Our objective was to evaluate the diagnostic performance of this test in a group of patients known to have GERD. Materials and methods: We included 123 individuals: 58 with GERD and 65 healthy controls. They underwent consecutive pH-impedance monitoring between January 2015 and June 2017. All had undergone endoscopy in the 6 months prior to testing. Criteria used for diagnosis of GERD were abnormal acid exposure time (AET > 4.2%), pyrosis and/or regurgitation in the previous 6 months. We found 58 patients with GERD of whom 24 had erosive reflux disease (ERE) and 34 had nonerosive reflux disease (NERD). The remaining 65 were asymptomatic healthy controls with normal endoscopic results and pH impedance monitoring. A second observer who did not know the previous data measurements analyzed all pH impedance monitoring traces for IBMN. Statistical analysis included multiple Bonferroni tests for comparison between groups, linear regression for continuous variables, and receiver operating characteristic (ROC) curve analysis to find high performance IBNM values. The IBNM cutoff point was used for diagnostic precision parameters. Statistical significance was set at p <0.01, and 95% confidence intervals were used for all calculations. Results: IBNM measures were significantly lower for patients with ERE and NERD than for the control group (p <0.01). A negative correlation was observed between IBNM and acid exposure time values (r = 0.59, p = <0.001) and also between IBNM and number of reflux events (r = 0.37, p = <0.001). ROC curve analysis found that the area under the curve for IBNM was 0.941 (95% CI: 0.894-0.987), and the cutoff point with the highest efficiency was 1,102 ohms (sensitivity 98.5%, specificity 84.5%). Using this value (<1.102), the IBNM had a sensitivity for detecting GERD of 91% (NERD 86% and ERE 100%) and a specificity of 98%. Conclusion: IBNM has high sensitivity and specificity for diagnosis of GERD. Addition of this test to conventional pH-impedance analysis and current methods for studying GERD can significantly improve our ability to diagnose this disease. [ABSTRACT FROM AUTHOR]

Background Acid exposure time ( AET) is considered the most useful parameter to predict response of reflux-related heartburn to medical or surgical treatment. However, recent studies showed high rates of heartburn response to proton pump inhibitor ( PPI) therapy in patients with normal AET. We aimed to compare the efficacy of postreflux swallow-induced peristaltic wave ( PSPW) index and mean nocturnal baseline impedance ( MNBI) with AET in linking PPI-responsive heartburn to reflux. Methods Off-therapy impedance- pH tracings from 425 patients, 317 with PPI-responsive and 108 with PPI-refractory heartburn were blindly re-analyzed. Demographic and endoscopic characteristics, conventional impedance- pH variables, PSPW index, and MNBI were assessed with multivariate logistic regression to identify factors independently associated with PPI responsiveness. Prediction models were developed to assess the strength of reflux linkage with factors independently associated with PPI responsiveness by calculating the area under the curve ( AUC) at receiver-operating-characteristic ( ROC) analysis. Key Results At multivariate logistic regression analysis, AET, MNBI, and PSPW index were the only factors independently associated with PPI responsiveness, abnormal values found in 60%, 76%, and 92% of PPI-responsive cases ( P<.017). At ROC analysis, PSPW index ( AUC:.794, P=.002) and MNBI ( AUC: 0.742, P=.003), both separately and combined ( AUC: 0.811, P<.001) linked reflux with PPI-responsiveness better than AET ( AUC: 0.687). Conclusions & Inferences AET, PSPW index, and MNBI are independently associated with PPI-responsive heartburn. PSPW index and MNBI can link PPI-responsive heartburn to reflux better than AET and should become part of the standard analysis of impedance- pH tracings. [ABSTRACT FROM AUTHOR]

Heartburn is the most specific symptom of gastroesophageal reflux disease (GERD). In clinical practice, heartburn relief by a proton pump inhibitor (PPI) trial does suffice to confirm GERD. However, an objective diagnosis of GERD is required before anti-reflux endoscopic or surgical interventions, independently from PPI response. Thus, since normal findings at upper endoscopy are detected in the majority of patients with heartburn, reflux monitoring is often required. When traditional catheter-based or wireless pH tests are used, reflux episodes are conventionally identified by pH drops below 4.0 units. Combined impedance-pH monitoring has the advantage to provide a comprehensive assessment of both physical and chemical properties of refluxate and the distinction between acid and weakly acidic refluxes, both proven to cause heartburn. Unfortunately, the conventional impedance-pH parameters, namely acid exposure time and number of reflux events, are characterized by suboptimal diagnostic sensitivity, and the reliability of symptom-reflux association indexes remains questionable. Therefore, novel impedance parameters, namely the post-reflux swallow-induced peristaltic wave (PSPW) index and the mean nocturnal baseline impedance (MNBI), have recently been proposed in order to achieve a better diagnostic yield. In fact, they proved to be highly accurate in distinguishing reflux-related from reflux-unrelated heartburn, off- as well as on-PPI therapy. Currently, manual review of impedance-pH tracings is needed because of the modest accuracy of available software tools for automated analysis. PSPW index and MNBI are highly applicable and reproducible, and their calculation requires a few additional minutes during the manual review of impedance-pH tracings. So far, we believe that PSPW index and MNBI are ready for prime time and should become part of the standard analysis of impedance-pH tracings for GERD diagnosis in patients with endoscopy-negative heartburn. [ABSTRACT FROM AUTHOR]

Background/Aims: The post-reflux swallow-induced peristaltic wave (PSPW) index and esophageal baseline impedance (BI) are novel impedance parameters used to evaluate esophageal chemical clearance and mucosal integrity. However, their relationship with reflux symptoms is not known. We aim to evaluate the correlations of PSPW index and esophageal BI with gastroesophageal reflux disease (GERD) symptoms. Methods: We performed a retrospective review of multichannel intraluminal impedance and pH (MII-pH) tracings in patients with suspected GERD. Reflux symptoms were also analyzed from checklists using ordinal scales. The PSPW index and esophageal BIs in 6 spots (z1-z6) were measured. Bivariate (Spearman) correlation was used to analyze the relationship between the PSPW index or esophageal BI, and the degree of GERD symptoms measured. Results: The MII-pH records of 143 patients were analyzed. The PSPW index was significantly lower in patients who had heartburn and negatively correlated with the degree of heartburn (r = -0.186, P < 0.05). On the contrary, the PSPW index was not significantly correlated with the degree of dysphagia (r = -0.013, P = 0.874). Distal esophageal BI was not significantly correlated with heartburn, but negatively correlated with the degree of dysphagia (z3: r = -0.328, z4: r = -0.361, z5: r = -0.316, z6: r = -0.273; P < 0.05). Conclusions: These findings suggest that delayed chemical clearance of the esophagus may induce heartburn, but that it is not related to dysphagia. However, a lack of esophageal mucosal integrity may be related to dysphagia. [ABSTRACT FROM AUTHOR]

Background On-therapy impedance- pH monitoring in proton pump inhibitor ( PPI)-refractory gastroesophageal reflux disease ( GERD) yielded conflicting results. We aimed to assess the diagnostic value of postreflux swallow-induced peristaltic wave ( PSPW) index and mean nocturnal baseline impedance ( MNBI) in PPI-refractory heartburn. Methods On-therapy impedance- pH tracings from 189 consecutive patients with PPI-refractory heartburn were blindly reviewed. Patients were subdivided into refractory reflux esophagitis ( RRE), healed reflux esophagitis ( HRE), non-erosive reflux disease ( NERD), and functional heartburn ( FH) according to endoscopic and conventional impedance- pH findings. The diagnostic accuracy of PSPW index and MNBI in separating NERD from FH was assessed with receiver-operating-characteristic ( ROC) analysis. Objectively documented persistent reflux remission at 3-year follow-up in 53 patients who underwent laparoscopic fundoplication served to evaluate PSPW index and MNBI as independent predictors of PPI-refractory GERD confirmed by positive surgical outcome. Key Results Median PSPW index and MNBI values were significantly lower in 39 RRE (16%; 1145 Ω) than in 41 HRE (25%; 1741 Ω) and in 68 NERD (29%; 2374 Ω) patients, and in all three GERD subgroups compared to 41 FH cases (67%; 3488 Ω) ( P<.008). At ROC analysis, comparing NERD to FH the area under the curve was 0.886 with PSPW index and 0.677 with MNBI ( P=.005). PSPW index was an independent predictor of PPI-refractory GERD (odds ratio 0.6983, P=.012). Conclusions & Inferences At on-therapy impedance- pH monitoring, PSPW index and MNBI efficiently distinguish PPI-refractory NERD from FH. The PSPW index represents an independent predictor of PPI-refractory GERD. [ABSTRACT FROM AUTHOR]

Background & Aims Analyses of impedance parameters such as the post-reflux swallow-induced peristaltic wave (PSPW) index and the mean nocturnal baseline impedance (MNBI) have been proposed to increase the accuracy of diagnosis of reflux disease. We assessed whether these improve the diagnostic yield of impedance pH monitoring of reflux disease. Methods We performed a prospective study of consecutive patients with proton pump inhibitor–responsive heartburn who underwent 24-hour impedance pH monitoring at hospitals in Italy from January 2011 through December 2013. Reviewers blindly analyzed off-therapy impedance pH tracings from 289 patients with proton pump inhibitor–responsive heartburn, 68 with erosive reflux disease and 221 with non-erosive reflux disease (NERD), along with 50 healthy individuals (controls). The PSPW index, the MNBI, the esophageal acid exposure time, the number of total refluxes, and the bolus exposure were calculated, as well as the symptom association probability (SAP) and the symptom index (SI). Results In receiver operating characteristic analysis, the area under curve of the PSPW index (0.977; 95% confidence interval, 0.961−0.993) was significantly greater than that of the other impedance pH parameters in identifying patients with reflux disease ( P < .001). The PSPW index and the MNBI identified patients with erosive reflux disease with the highest level of sensitivity (100% and 91%, respectively), as well as the 118 pH-positive (99% and 86%) and 103 pH-negative (77% and 56%) cases of NERD. The PSPW index and the MNBI identified pH-negative NERD with the highest level of sensitivity; values were 82% and 52% for the 65 SAP-positive and/or SI-positive cases and 68% and 63% for the 38 SAP-negative and SI-negative cases. Diagnoses of NERD were confirmed by pH-only criteria, including those that were positive on the basis of the SAP or SI, for 165 of 221 cases (75%) and by impedance pH criteria for 216 of 221 cases (98%) ( P = .001). Conclusions The PSPW index and the MNBI increase the diagnostic yield of impedance pH monitoring of patients with reflux disease. Analysis of impedance pH data by calculating the PSPW index and the MNBI can increase the accuracy of diagnosis of patients with reflux disease, compared with pH-only data. [ABSTRACT FROM AUTHOR]