title: Comparison of esophageal acid exposure distribution along the esophagus among the different gastroesophageal reflux disease (GERD) groups.
abstract: BACKGROUND
  Patients with nonerosive reflux disease (NERD) have the lowest esophageal acid exposure profile compared with the other gastroesophageal reflux disease (GERD) groups.
  
  
  OBJECTIVE
  To compare lower esophageal acid exposure recordings 1 cm above the lower esophageal sphincter (LES) with those 6 cm above the LES as well as to determine the characteristics of esophageal acid exposure along the esophagus among the different GERD groups.
  
  
  METHODS
  Patients with classic heartburn symptoms were enrolled into the study. Patients were evaluated by a demographics questionnaire and the validated GERD Symptom Checklist. Upper endoscopy was performed to evaluate the presence of esophageal erosions and Barrett's esophagus (BE). Ambulatory pH testing was performed using a commercially available 4-sensor pH probe with sensors located 5 cm apart. The distal sensor was placed 1 cm above the LES.
  
  
  RESULTS
  Sixty-four patients completed the study. Of those, 21 patients had NERD, 20 had erosive esophagitis (EE), and 23 had BE. All patient groups demonstrated greater esophageal acid exposure 1 cm above the LES than 6 cm above the LES. In NERD and EE, this phenomenon was primarily a result of a higher mean percentage of upright time with pH <4. Unlike patients with EE and BE, those with NERD had very little variation in esophageal acid exposure throughout the esophagus (total and supine).
  
  
  CONCLUSIONS
  ALL GERD groups demonstrated significant greater esophageal acid exposure at the very distal portion of the esophagus, primarily as a result of short upright reflux events. Unlike erosive esophagitis and BE, NERD patients demonstrate a more homogenous acid distribution along the esophagus.
authors.affiliation: The Neuro-Enteric Clinical Research Group, Department of Medicine, Section of Gastroenterology, Southern Arizona VA Health Care System, Tucson, Arizona 85723-0001, USA.
authors.forename: Ram
authors.initials: R
authors.lastname: Dickman
authors.forename: Jimmy M
authors.initials: JM
authors.lastname: Bautista
authors.forename: Wai-Man
authors.initials: WM
authors.lastname: Wong
authors.forename: Rajan
authors.initials: R
authors.lastname: Bhatt
authors.forename: Joy N
authors.initials: JN
authors.lastname: Beeler
authors.forename: Isaac
authors.initials: I
authors.lastname: Malagon
authors.forename: Sara
authors.initials: S
authors.lastname: Risner-Adler
authors.forename: Kwok-Fai
authors.initials: KF
authors.lastname: Lam
authors.forename: Ronnie
authors.initials: R
authors.lastname: Fass
mesh_terms: D000328:Adult; D000368:Aged; D001471:Barrett Esophagus / Q000150:complications; D004941:Esophagitis / Q000473:pathology; D004945:Esophagoscopy; D005260:Female; D005744:Gastric Acid / Q000378:metabolism*; D005764:Gastroesophageal Reflux / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged