title: The position of the acid pocket as a major risk factor for acidic reflux in healthy subjects and patients with GORD.
abstract: BACKGROUND
  Gastro-oesophageal reflux occurs twice as much during transient lower oesophageal sphincter relaxations (TLOSRs) in patients with gastro-oesophageal reflux disease (GORD) compared to healthy volunteers (HVs). Our aim was to assess whether the localisation of the postprandial acid pocket and its interaction with a hiatal hernia (HH) play a role in the occurrence of acidic reflux during TLOSRs.
  
  
  METHODS
  Ten HVs and 22 patients with GORD (12 with HH<3 cm (s-HH), 10 with HH > or =3 cm (l-HH)) were studied. The squamocolumnar junction and diaphragmatic impression were marked with a radioactively labelled clip. To visualise the acid pocket, (99m)Tc-pertechnetate was injected intravenously and images were acquired up to 2 h postprandial. Concurrently, combined manometry/impedance and four-channel pH-metry were performed, with pH pull-through at multiple time-points.
  
  
  RESULTS
  The rate of TLOSRs and the per cent associated with reflux was comparable between all groups. However, acidic reflux was significantly increased in patients, especially in patients with l-HH. Acid pocket length was significantly enlarged in patients. Moreover, immediately before a TLOSR, the acid pocket was more frequently located within the hiatus or above the diaphragm in patients with GORD (s-HH, 54%; l-HH, 77%) compared to HVs (22% of TLOSRs). Acidic reflux was significantly increased when the acid pocket was located above the diaphragm in all groups compared to a sub-diaphragmatic localisation.
  
  
  CONCLUSIONS
  The position of the acid pocket is largely determined by the presence of a HH. Entrapment of the pocket above the diaphragm, especially in patients with l-HH, is a major risk factor underlying the increased occurrence of acidic reflux during a TLOSR in patients with GORD.
authors: Academic Medical Center, Department of Gastroenterology and Hepatology, Amsterdam, The Netherlands.
authors: Hanneke
authors: H
authors: Beaumont
authors: Roelof J
authors: RJ
authors: Bennink
authors: Jan
authors: J
authors: de Jong
authors: Guy E
authors: GE
authors: Boeckxstaens
mesh_terms: D000328:Adult; D000368:Aged; D004943:Esophagogastric Junction / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D005744:Gastric Acid / Q000378:metabolism*; D005745:Gastric Acidity Determination; D005764:Gastroesophageal Reflux / Q000000981:diagnostic imaging / Q000209:etiology* / Q000378:metabolism; D006551:Hernia, Hiatal / Q000150:complications* / Q000378:metabolism; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods; D008875:Middle Aged; D019518:Postprandial Period / Q000502:physiology; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012307:Risk Factors; D013670:Sodium Pertechnetate Tc 99m; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D013670:Sodium Pertechnetate Tc 99m