title: Normal values and day-to-day variability of 24-h ambulatory oesophageal impedance-pH monitoring in a Belgian-French cohort of healthy subjects.
abstract: BACKGROUND
  Impedance-pH monitoring is the most sensitive method for detection and characterization of gastro-oesophageal reflux episodes. Normal values from European subjects are lacking.
  
  
  OBJECTIVE
  To build a database of gastro-oesophageal reflux patterns from French and Belgian healthy subjects.
  
  
  METHODS
  Seventy-two healthy subjects (35 men, mean age 35 years, 18-72) underwent 24-h ambulatory impedance-pH studies. Gastro-oesophageal reflux episodes were detected using impedance and characterized by pH as acid, weakly acidic, or weakly alkaline. Analysis was performed visually and effects of age, gender and intra-individual reproducibility were evaluated.
  
  
  RESULTS
  The total number of gastro-oesophageal reflux episodes was 44 (25,58,75) of which 59% were acid, 28% were weakly acidic and 10% weakly alkaline. Half of gastro-oesophageal reflux episodes were mixed (liquid/gas) and 22% reached 15 cm above the lower oesophageal sphincter. The bolus clearance time was 11 s while acid was chemically cleared in 34 s. Male gender was associated with increased number and proximal extent of total and acid gastro-oesophageal reflux. Repeated studies in 27 subjects showed good reproducibility for number, acidity and air-liquid composition of reflux (Kendall's W-values = 0.72-0.85).
  
  
  CONCLUSIONS
  This study demonstrates good reproducibility of 24-h ambulatory impedance-pH studies and provides values of reflux patterns in healthy subjects for comparisons with European gastro-oesophageal reflux disease patients.
authors.affiliation: Gastroenterology Department, Saint André Hospital, Bordeaux, France.
authors.forename: F
authors.initials: F
authors.lastname: Zerbib
authors.forename: S Bruley
authors.initials: SB
authors.lastname: des Varannes
authors.forename: S
authors.initials: S
authors.lastname: Roman
authors.forename: P
authors.initials: P
authors.lastname: Pouderoux
authors.forename: F
authors.initials: F
authors.lastname: Artigue
authors.forename: U
authors.initials: U
authors.lastname: Chaput
authors.forename: F
authors.initials: F
authors.lastname: Mion
authors.forename: F
authors.initials: F
authors.lastname: Caillol
authors.forename: E
authors.initials: E
authors.lastname: Verin
authors.forename: G
authors.initials: G
authors.lastname: Bommelaer
authors.forename: P
authors.initials: P
authors.lastname: Ducrotté
authors.forename: J-P
authors.initials: JP
authors.lastname: Galmiche
authors.forename: D
authors.initials: D
authors.lastname: Sifrim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017097:Electric Impedance; D004947:Esophagus / Q000378:metabolism*; D005260:Female; D005744:Gastric Acid / Q000378:metabolism*; D005745:Gastric Acidity Determination; D005764:Gastroesophageal Reflux / Q000175:diagnosis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results