title: Mechanisms of acid, weakly acidic and gas reflux after anti-reflux surgery.
abstract: BACKGROUND
  Whereas it is well documented that fundoplication reduces acid reflux, the effects of the procedure on non-acid and gas reflux and the mechanisms through which this is achieved have not been fully elucidated.
  
  
  METHODS
  In 14 patients, reflux was measured with impedance-pH monitoring during a postprandial 90 min stationary recording period before and 3 months after fundoplication. Concomitantly, the occurrence of transient lower oesophageal sphincter relaxations (TLOSRs) and morphology of the oesophagogastric junction were studied with high-resolution manometry. This was followed by 24 h ambulatory impedance-pH monitoring.
  
  
  RESULTS
  Before fundoplication, two separate high-pressure zones (hernia profile) were detected during 24.9% of total time, during which there was a large increase in reflux rate. After fundoplication, the hernia profile did not occur. Fundoplication decreased the number of TLOSRs (from 10.5 (SEM 1.2) to 4.5 (0.7), p<0.01) and also the percentage of TLOSRs associated with acidic or weakly acidic reflux (from 72.7% to 4.1%, p<0.01). Nadir pressure during TLOSRs increased after surgery (from 0 (0-0) to 1.0 (1-2) kPa, p<0.05). In the ambulatory study, there was a large decrease in prevalence of both acid (-96%, from 47.0 (5.9) to 1.8 (0.5), p<0.01) and weakly acidic reflux (-92%, from 25.0 (9.7) to 2.3 (0.9), p<0.01). The decrease in gas reflux was less pronounced (-53%, from 24.2 (4.9) to 11.3 (3.0), p<0.01).
  
  
  CONCLUSIONS
  Fundoplication greatly reduces both acid and weakly acidic liquid reflux; gas reflux is reduced to a lesser extent. Three mechanisms play a role: (1) abolition of the double high-pressure zone profile (hiatal hernia); (2) reduced incidence of TLOSRs; and (3) decreased percentage of TLOSRs associated with reflux.
authors: Department of Gastroenterology, St Antonius Hospital, PO Box 2500, 3430 EM Nieuwegein, The Netherlands. a.bredenoord@antonius.net
authors: A J
authors: AJ
authors: Bredenoord
authors: W A
authors: WA
authors: Draaisma
authors: B L A M
authors: BL
authors: Weusten
authors: H G
authors: HG
authors: Gooszen
authors: A J P M
authors: AJ
authors: Smout
mesh_terms: D000328:Adult; D000368:Aged; D004884:Eructation; D004935:Esophageal Diseases / Q000628:therapy*; D050782:Esophageal pH Monitoring; D004943:Esophagogastric Junction / Q000503:physiopathology*; D005260:Female; D018662:Fundoplication / Q000379:methods / Q000534:rehabilitation*; D005764:Gastroesophageal Reflux / Q000503:physiopathology* / Q000601:surgery*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008365:Manometry; D008875:Middle Aged