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

Background: According to the Lyon Consensus 2.0, mean nocturnal baseline impedance (MNBI) greater than 2500 Ω is considered evidence against gastroesophageal reflux disease (GERD). However, we have observed that a subset of GERD patients presents with MNBI exceeding 2500 Ω.

Aims: To investigate MNBI characteristics in Chinese GERD patients, identify clinical features of those with normal MNBI, and examine factors influencing MNBI values.

Methods: We 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.

Results: Among 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 Ω. Independent risk factors for MNBI > 2500 Ω 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 Ω had higher PPI response than MNBI > 2500 Ω (81.1% vs. 55.6%, p = 0.009).

Conclusions: Approximately one-third of Chinese GERD patients have an MNBI > 2500 Ω. 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.