title: Esophageal baseline impedance levels in patients with pathophysiological characteristics of functional heartburn.
abstract: BACKGROUND
  Recently, it has been suggested that low esophageal basal impedance may reflect impaired mucosal integrity and increased acid sensitivity. We aimed to compare baseline impedance levels in patients with heartburn and pathophysiological characteristics related to functional heartburn (FH) divided into two groups on the basis of symptom relief after proton pump inhibitors (PPIs).
  
  
  METHODS
  Patients with heartburn and negative endoscopy were treated with esomeprazole or pantoprazole 40 mg daily for 8 weeks. According to MII-pH (off therapy) analysis, patients with normal acid exposure time (AET), normal reflux number, and lack of association between symptoms and refluxes were selected; of whom 30 patients with a symptom relief higher than 50% after PPIs composed Group A, and 30 patients, matched for sex and age, without symptom relief composed Group B. A group of 20 healthy volunteers (HVs) was enrolled. For each patient and HV, we evaluated the baseline impedance levels at channel 3, during the overnight rest, at three different times.
  
  
  RESULTS
  Group A (vs Group B) showed an increase in the following parameters: mean AET (1.4 ± 0.8% vs 0.5 ± 0.6%), mean reflux number (30.4 ± 8.7 vs 24 ± 6.9), proximal reflux number (11.1 ± 5.2 vs 8.2 ± 3.6), acid reflux number (17.9 ± 6.1 vs 10.7 ± 6.9). Baseline impedance levels were lower in Group A than in Group B and in HVs (p < 0.001).
  
  
  CONCLUSIONS
  Evaluating baseline impedance levels in patients with heartburn and normal AET could achieve a better understanding of pathophysiology in reflux disease patients, and could improve the distinction between FH and hypersensitive esophagus.
authors.affiliation: Division of Gastroenterology, University of Pisa, Pisa, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Martinucci
authors.forename: N
authors.initials: N
authors.lastname: de Bortoli
authors.forename: E
authors.initials: E
authors.lastname: Savarino
authors.forename: P
authors.initials: P
authors.lastname: Piaggi
authors.forename: M
authors.initials: M
authors.lastname: Bellini
authors.forename: A
authors.initials: A
authors.lastname: Antonelli
authors.forename: V
authors.initials: V
authors.lastname: Savarino
authors.forename: M
authors.initials: M
authors.lastname: Frazzoni
authors.forename: S
authors.initials: S
authors.lastname: Marchi
mesh_terms: D053799:2-Pyridinylmethylsulfinylbenzimidazoles / Q000627:therapeutic use; D017097:Electric Impedance; D064098:Esomeprazole / Q000627:therapeutic use; D050782:Esophageal pH Monitoring; D004947:Esophagus / Q000503:physiopathology*; D005260:Female; D005764:Gastroesophageal Reflux / Q000188:drug therapy / Q000503:physiopathology*; D006356:Heartburn / Q000188:drug therapy / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077402:Pantoprazole; D054328:Proton Pump Inhibitors / Q000627:therapeutic use
chemical_list: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D054328:Proton Pump Inhibitors; D000077402:Pantoprazole; D064098:Esomeprazole
keywords: GERD/GORD; PPI; esophageal sensitivity; functional heartburn; multichannel impedance and pH