Mean Nocturnal Baseline Impedance May Be Greater Than 2500 Ohms in Chinese Patients With GERD

BackgroundAccording to the Lyon Consensus 2.0, mean nocturnal baseline impedance (MNBI) greater than 2500 Omega is considered evidence against gastroesophageal reflux disease (GERD). However, we have observed that a subset of GERD patients presents with MNBI exceeding 2500 Omega. AimsTo investigate MNBI characteristics in Chinese GERD patients, identify clinical features of those with normal MNBI, and examine factors influencing MNBI values. MethodsWe retrospectively investigated 259 patients with typical reflux symptoms. Demographics, symptoms, proton pump inhibitor (PPI) response, esophageal motility parameters were compared between patients with different AET levels and MNBI levels. ResultsAmong the cohort, 38.2% had AET 4%-6%, and 37.5% had AET > 6%. Notably, 95.2% of patients with AET < 4%, 49.5% with AET 4%-6%, and 17.6% with AET > 6% had MNBI > 2500 Omega. Independent risk factors for MNBI > 2500 Omega included the number and duration of supine acid reflux and lower esophageal sphincter (LES) resting pressure. In GERD patients with heartburn, patients with MNBI <= 2500 Omega had higher PPI response than MNBI > 2500 Omega (81.1% vs. 55.6%, p = 0.009). ConclusionsApproximately one-third of Chinese GERD patients have an MNBI > 2500 Omega. The thresholds of MNBI for supporting or ruling out GERD in the Chinese population should be adjusted. MNBI values are independently predicted by the severity of supine acid reflux and the LES resting pressure. GERD patients with mild supine acid reflux may still exhibit normal MNBI levels. Patients with lower MNBI values tend to show better responses to PPI therapy.