Baseline impedance via manometry and ambulatory reflux testing are not equivalent when utilized in the evaluation of potential extra-esophageal gastroesophageal reflux disease

Abstract

Background: Esophageal baseline impedance (BI) shows promise for the diagnosis of gastroesophageal reflux disease (GERD), but means of acquisition and relevance to extra-esophageal manifestations of GERD (EE-GERD) remain unclear. In this study we aim to (I) evaluate concordance between BI as measured by 24-hour pH-impedance (pH-MII) and high-resolution impedance manometry (HRIM), and (II) assess relationship to potential EE-GERD symptoms. Methods: In this prospective open cohort study, patients presenting for outpatient HRIM and pH-MII studies were prospectively enrolled. All patients completed the GERD-HRQL, NOSE, and respiratory symptom index questionnaire (RSI), plus questions regarding wheezing and dental procedures. HRIM and pH-MII were evaluated with calculation of BI. Correlations were assessed using either Pearson's correlation or Spearman's rank coefficients.Results: 70 HRIM patients were enrolled, 35 of whom underwent pH-MII. There was no correlation between BI measurements as assessed by HRIM and pH-MII proximally, but there was moderate-weak correlation distally (r=0.34 to 0.5). Distal acid exposure time correlated with distal BI only for measurements by pH-MII (rho= −0.5 to −0.65), and not by HRIM. There was no relationship between proximal acid exposure time and proximal BI. There were no correlations when comparing proximal or distal BI measurements, acid exposure times, and impedance events to symptoms. Conclusions: Concordance between BI as measured by HRIM and pH-MII is poor, especially proximally, suggesting that these two methods are not interchangeable. There is no correlation between BI both distally/ proximally and symptoms of either GERD/EE-GERD, suggesting that many symptoms are unrelated to acid or that BI is not an adequate marker to assess EE-GERD symptoms.

Diagnostic Yield of Ambulatory Reflux Monitoring Systems for Evaluation of Chronic Laryngeal Symptoms

“…Another additional component of impedance testing that can potentially improve diagnostic yield is MNBI. Studies have shown poor correlation between extraesophageal symptoms and MNBI, both in the distal and proximal esophagus (23). Other studies have demonstrated that distal, but not proximal, esophageal MNBI can predict pathologic reflux in patients with isolated laryngeal reflux symptoms (24).…”

Mean nocturnal baseline impedance, a novel metric of multichannel intraluminal impedance-pH monitoring in diagnosing gastroesophageal reflux disease

“…However, some other studies noted that MNBI was not sufficient to evaluate patients with EES. 41 , 42 Doo et al 41 showed that there was no significant difference in the MNBI values of distal and proximal esophageal (Z6 and Z3, respectively) between patients with LPR and healthy controls. In addition, Zikos et al 42 found that there was no correlation between distal/proximal MNBI and EES.…”

“… 41 , 42 Doo et al 41 showed that there was no significant difference in the MNBI values of distal and proximal esophageal (Z6 and Z3, respectively) between patients with LPR and healthy controls. In addition, Zikos et al 42 found that there was no correlation between distal/proximal MNBI and EES. Whether MNBI can improve the diagnostic rate of GERD patients or predict the response to anti-reflux therapy in patients with EES or atypical symptoms is an open question to be explored in future studies.…”

“…27,28 The use of MNBI in diagnosing patients with atypical symptoms or extra-esophageal symptoms Few data are available concerning MNBI in patients with atypical symptoms or extra-esophageal symptoms (EES). [37][38][39][40][41][42] Zhong et al 37 demonstrated that in MII-pH monitoring, the BI (Z2-Z6) of GERD patients with chest pain syndrome and EES was significantly lower than that of healthy controls. Ribolsi et al 38 studied 239 EES patients in Italy.…”