title: Patterns of gas and liquid reflux during transient lower oesophageal sphincter relaxation: a study using intraluminal electrical impedance.
abstract: BACKGROUND
  Belching has been proposed as a major mechanism underlying acid gastro-oesophageal reflux in normal subjects. However, the presence of oesophageal gas has not been measured directly but only inferred from manometry.
  
  
  OBJECTIVE
  To investigate, using intraluminal electrical impedance, the patterns of gas and liquid reflux during transient lower oesophageal sphincter (LOS) relaxations, the main mechanism of acid reflux in normal subjects.
  
  
  METHODS
  Impedance changes associated with the passage of gas were studied in vitro, and in vivo in cats. Oesophageal manometry, pH, and intraluminal electrical impedance measurements were performed in 11 normal subjects after a meal.
  
  
  RESULTS
  Gas reflux caused a sudden increase in impedance that propagated rapidly to the proximal oesophagus whereas liquid reflux induced a retrogressively propagated fall in impedance. Impedance showed gas or liquid reflux during most (102/141) transient LOS relaxations. When acid reflux occurred, impedance showed evidence of intraoesophageal retrograde flow of liquid in the majority (78%) of events. Evidence of gas retroflow was found in almost half (47%) of acid reflux episodes. When present together, however, liquid preceded gas on 44% of occasions. Overall, gas reflux occurred as the initial event in only 25% of acid reflux episodes.
  
  
  CONCLUSIONS
  These findings suggest that in upright normal subjects, although belching can precipitate acid reflux, most acid reflux occurs as a primary event.
authors.affiliation: Centre for Gastroenterological Research, University of Leuven, Leuven, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Sifrim
authors.forename: J
authors.initials: J
authors.lastname: Silny
authors.forename: R H
authors.initials: RH
authors.lastname: Holloway
authors.forename: J J
authors.initials: JJ
authors.lastname: Janssens
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D002415:Cats; D017097:Electric Impedance; D004884:Eructation / Q000150:complications*; D004947:Esophagus / Q000503:physiopathology; D005260:Female; D005502:Food; D005740:Gases / Q000378:metabolism*; D005764:Gastroesophageal Reflux / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008365:Manometry; D009126:Muscle Relaxation / Q000502:physiology; D015203:Reproducibility of Results; D012996:Solutions
chemical_list: D005740:Gases; D012996:Solutions