title: Normal values in ambulatory oesophageal pH monitoring at two levels in Spain.
abstract: OBJECTIVE
  Upper oesophageal pH monitoring may play a significant role in the study of extra-oesophageal GERD, but limited normal data are available to date. Our aim was to develop a large series of normal values of proximal oesophageal acidification.
  
  
  METHODS
  155 healthy volunteers (74 male) participated in a multi-centre national study including oesophageal manometry and 24 hours oesophageal pH monitoring using two electrodes individually located 5 cm above the LOS and 3 cm below the UOS.
  
  
  RESULTS
  130 participants with normal manometry completed all the study. Twelve of them were excluded for inadequate pH tests. Twenty-seven subjects had abnormal conventional pH. The remaining 91 subjects (37 M; 18-72 yrs age range) formed the reference group for normality. At the level of the upper oesophagus, the 95th percentile of the total number of reflux events was 30, after eliminating the meal periods 22, and after eliminating also the pseudo-reflux events 18. Duration of the longest episodes was 5, 4 and 4 min, respectively (3.5 min in upright and 0.5 min in supine). The upper limit for the percentage of acid exposure time was 1.35, 1.05 and 0.95%, respectively. No reflux events were recorded in the upper oesophagus in 8 cases.
  
  
  CONCLUSIONS
  This is the largest series of normal values of proximal oesophageal reflux that confirm the existence of acid reflux at that level in healthy subjects, in small quantity and unrelated to age or gender. Our data support the convenience of excluding pseudo-reflux events and meal periods from analysis.
authors.forename: F
authors.initials: F
authors.lastname: Azpiroz
authors.forename: J S
authors.initials: JS
authors.lastname: Baudet
authors.forename: A
authors.initials: A
authors.lastname: Benages
authors.forename: F
authors.initials: F
authors.lastname: Canga
authors.forename: J
authors.initials: J
authors.lastname: Carrasco
authors.forename: C
authors.initials: C
authors.lastname: Ciriza
authors.forename: M
authors.initials: M
authors.lastname: Cucala
authors.forename: E
authors.initials: E
authors.lastname: Domínguez
authors.forename: V
authors.initials: V
authors.lastname: Faro
authors.forename: V
authors.initials: V
authors.lastname: Garrigues
authors.forename: F
authors.initials: F
authors.lastname: Giganto
authors.forename: J M
authors.initials: JM
authors.lastname: Herrerías
authors.forename: J
authors.initials: J
authors.lastname: Iglesias
authors.forename: G
authors.initials: G
authors.lastname: Lacima
authors.forename: P
authors.initials: P
authors.lastname: López
authors.forename: M
authors.initials: M
authors.lastname: Llabrés
authors.forename: F
authors.initials: F
authors.lastname: Mearin
authors.forename: M
authors.initials: M
authors.lastname: Mínguez
authors.forename: J
authors.initials: J
authors.lastname: Monés
authors.forename: F
authors.initials: F
authors.lastname: Mora
authors.forename: C
authors.initials: C
authors.lastname: Muñoz
authors.forename: J
authors.initials: J
authors.lastname: Pérez de la Serna
authors.forename: J
authors.initials: J
authors.lastname: Ponce
authors.forename: M
authors.initials: M
authors.lastname: Rodríguez-Téllez
authors.forename: M J
authors.initials: MJ
authors.lastname: Romero
authors.forename: A
authors.initials: A
authors.lastname: Ruiz de León
authors.forename: M
authors.initials: M
authors.lastname: Ruiz-Cabello
authors.forename: S
authors.initials: S
authors.lastname: Sánchez-Gey
authors.forename: V
authors.initials: V
authors.lastname: Sanchíz
authors.forename: J
authors.initials: J
authors.lastname: Serra
authors.forename: M C
authors.initials: MC
authors.lastname: Sevilla
authors.forename: F
authors.initials: F
authors.lastname: Sopeña
authors.forename: M J
authors.initials: MJ
authors.lastname: Soria
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000553:Ambulatory Care; D050782:Esophageal pH Monitoring; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013030:Spain; D055815:Young Adult