title: The postprandial acid pocket does not extend into most distal esophagus: evidence from pH studies performed immediately above the squamocolumnar junction.
abstract: OBJECTIVE
  The postprandial acid pocket is suggested to be an important factor in the pathogenesis of gastroesophageal reflux disease (GERD) as it according to the theory extends into the distal esophagus. The aim of this study was to test the hypothesis that the acid pocket transverses the squamocolumnar junction (SCJ) and exposes the most distal esophagus to gastric acid for extended periods following a meal.
  
  
  METHODS
  Fifty asymptomatic volunteers and 75 patients with GERD underwent 48-h pH monitoring with the electrode of a pH capsule placed immediately above the SCJ. The characteristics of esophageal acid exposure from the 90-min postprandial periods were compared with those observed during the upright, preprandial periods.
  
  
  RESULTS
  In asymptomatic controls, the degree of postprandial esophageal acid exposure was similar to that observed in the preprandial periods (median % time with pH <4, 2.2 vs. 2.6, p = 0.165). In contrast, symptomatic patients had significantly greater acid exposure in the postprandial compared with the preprandial periods (median % time with pH <4, 15.5 vs. 8.5, p < 0.001). The higher degree of acid exposure during the postprandial periods was due to a significantly higher number of short reflux episodes and reflux events with long durations were infrequent.
  
  
  CONCLUSIONS
  Postprandial acid exposure in the most distal esophagus was characterized by numerous short reflux events, and reflux events of long durations were rare. Our observations suggest that the acid pocket is confined to the stomach, questioning the importance of the acid pocket in GERD.
authors.affiliation: Department of Gastroenterology, Skåne University Hospital, Clinical Sciences Lund, Lund University.
authors.forename: Mats
authors.initials: M
authors.lastname: Hall
authors.forename: Jörgen
authors.initials: J
authors.lastname: Wenner
authors.forename: Stefan
authors.initials: S
authors.lastname: Öberg
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D050782:Esophageal pH Monitoring; D004947:Esophagus / Q000737:chemistry*; D005260:Female; D005744:Gastric Acid / Q000737:chemistry; D005745:Gastric Acidity Determination; D005764:Gastroesophageal Reflux; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period