title: NERD, GERD, and Barrett's esophagus: role of acid and non-acid reflux revisited with combined pH-impedance monitoring.
abstract: BACKGROUND
  Gastroesophageal reflux is the most important factor in the development of Barrett's metaplasia. The effect of acid reflux is commonly accepted today, but there is controversy about the role of non-acid reflux. With introduction of combined esophageal pH-impedance monitoring, a precise diagnostic test for acid and non-acid reflux is now available.
  
  
  METHODS
  Ninety two consecutive patients (33 women) off acid-suppressive therapy underwent diagnostic work-up for suspected gastroesophageal reflux disease including upper-GI endoscopy, esophageal manometry, barium swallow, and combined esophageal pH-impedance monitoring. Patients were subdivided into three groups according to symptoms and endoscopic appearance: typical symptoms without esophagitis (n = 28; NERD); erosive esophagitis (n = 52, ERD), and patients with intestinal metaplasia (n = 12, BE).
  
  
  RESULTS
  Pathologic acid reflux during pH-metry was found in 35.7%, 63.5%, and 75.0% for NERD, ERD, and BE patients, respectively (P = 0.022). Likewise, the percentage of time pH < 4 rose significantly during upright, supine, and total phases. In contrast, combined pH-impedance monitoring showed no significant difference between groups for the number of acid reflux events and for percentage of acid bolus reflux time. However, BE patients had significantly more non-acid reflux events and a higher percentage of non-acid bolus reflux time during the supine (P = 0.043, P = 0.020, respectively), but not during the upright phase (P = 0.740, P = 0.730, respectively).
  
  
  CONCLUSIONS
  Patients with BE are exposed to increased supine non-acid reflux and to increased acid reflux during upright and supine phases. This observation supports the concept that nocturnal non-acid reflux may play a role in the pathogenesis of BE.
authors.affiliation: Department of Visceral and Vascular Surgery, University of Cologne, Kerpener Strasse 62, 50962, Cologne, Germany. ch.gutschow@t-online.de
authors.forename: Christian A
authors.initials: CA
authors.lastname: Gutschow
authors.forename: Marc
authors.initials: M
authors.lastname: Bludau
authors.forename: Daniel
authors.initials: D
authors.lastname: Vallböhmer
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schröder
authors.forename: Elfriede
authors.initials: E
authors.lastname: Bollschweiler
authors.forename: Arnulf H
authors.initials: AH
authors.lastname: Hölscher
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001471:Barrett Esophagus / Q000503:physiopathology*; D001647:Bile Acids and Salts; D016145:Endoscopy, Digestive System; D050782:Esophageal pH Monitoring; D004941:Esophagitis / Q000503:physiopathology*; D005260:Female; D005764:Gastroesophageal Reflux / Q000503:physiopathology*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000473:pathology; D008297:Male; D008365:Manometry; D008679:Metaplasia; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D001647:Bile Acids and Salts