title: Characteristics of gastroesophageal reflux in symptomatic patients with and without excessive esophageal acid exposure.
abstract: OBJECTIVE
  In some patients with a physiological esophageal acid exposure, an association between reflux episodes and symptoms can be demonstrated. Besides acidity, other factors such as proximal extent may determine whether a reflux episode is perceived or not. We aimed to investigate the reflux profile of gastroesophageal reflux disease (GERD) patients with physiological acid exposure.
  
  
  METHODS
  Twenty-four-hour impedance-pH monitoring was performed in 14 GERD patients with excessive acid exposure (pH+), 14 GERD patients with physiological acid exposure (pH-), and 14 controls. All patients had a positive symptom-reflux association during 24-h monitoring (SAP+).
  
  
  RESULTS
  The incidence of acid reflux episodes in pH- SAP+ patients (25.5 +/- 4.9) and controls (20.2 +/- 3.9) was comparable, but lower than in pH+ SAP+ patients (69.8 +/- 7.3). However, no differences in number of weakly acidic reflux episodes were observed among pH- SAP+ patients, pH+ SAP+ patients, and controls (27.2 +/- 3.8 vs 26.8 +/- 4.6 and 21.0 +/- 3.7, respectively). The proportion of reflux episodes that reached the proximal esophagus was significantly higher in the pH+ SAP+ (33.5%) and pH- SAP+ (36.0%) patients than in the controls (19.5%). Volume clearance time was longer in pH+ SAP+ (12.5 [12.5-17.0] s) compared with pH- SAP+ patients (12.0 [11.0-16.5] s) and controls (9.5 [10.0-12.5] s) (P < 0.05). Acid clearance time was also longer in pH+ SAP+ patients (55.0 [32.0-64.0] s) compared with the pH- SAP+ (16.5 [11.4-40.0] s) and controls (14 [12.0-19.1] s) (P < 0.01).
  
  
  CONCLUSIONS
  In pH- SAP+ patients, a higher proportion of reflux episodes reach the proximal esophagus than in controls. This can in part explain their symptoms.
authors.affiliation: Department of Gastroenterology, Sint Antonius Hospital, Nieuwegein, The Netherlands.
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Bredenoord
authors.forename: Bas L A M
authors.initials: BL
authors.lastname: Weusten
authors.forename: Robin
authors.initials: R
authors.lastname: Timmer
authors.forename: Andŕe J P M
authors.initials: AJ
authors.lastname: Smout
mesh_terms: D000328:Adult; D005260:Female; D005744:Gastric Acid / Q000378:metabolism*; D005764:Gastroesophageal Reflux / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged