Evaluation of Baseline Impedance During Water-perfused High Resolution Impedance Manometry in Patients With Symptomatic GERD

Goals: We aimed to investigate the hypothesis whether baseline impedance measured during water-perfused high resolution impedance manometry (HRIM) can help discriminate patients with reflux symptoms from the controls and predict the response to the proton pump inhibitors (PPIs). Background/Aim: Baseline impedance measured during solid-state HRIM can reliably discriminate patients with gastroesophageal reflux disease (GERD) from controls. Study: We enrolled consecutive patients with typical reflux symptoms and healthy controls for the measurement of baseline impedance during the landmark period of HRIM. All patients were given PPIs and PPI response was assessed after 8 weeks of the treatment. Results: Baseline mucosa impedance measured during HRIM was lower in GERD patients than the controls (1861 +/- 183 vs. 3371 +/- 250 omega; P<0.001). Baseline impedance during water-perfused HRIM had moderate diagnostic accuracy for differentiating symptomatic GERD with an area under the curve of 0.853 on receiver operating characteristics analysis. A threshold of 2530 omega for baseline impedance had a sensitivity of 88.3% and specificity of 82.4% for GERD with a positive predictive value of 83.4% and negative predictive value of 87.6%. Among symptomatic GERD patients, poor PPI responders had higher baseline impedance than those without it (2340 +/- 260 vs. 1479 +/- 189 omega; P=0.02). BMI negatively correlated to base impedance in either controls (r=-0.59; P=0.012) or GERD patients (r=-0.47; P=0.047). Conclusions: Baseline impedance measurement during water-perfused HRIM helps differentiate patients with typical reflux symptoms from controls and also serves as a potential utility in predicting PPI response.