title: Normal 24-hour ambulatory proximal and distal gastroesophageal reflux parameters in Chinese.
abstract: OBJECTIVE
  To quantify normal proximal and distal oesophageal acid parameters in healthy Chinese.
  
  
  METHODS
  Observational study.
  
  
  METHODS
  University teaching hospital, Hong Kong.
  
  
  METHODS
  Twenty healthy adults who were not on medication and were free from gastrointestinal symptoms were recruited by advertisement. Ambulatory oesophageal acid (pH<4) exposure parameters were recorded at distal and proximal sites, 5 and 20 cm, respectively above the lower oesophageal sphincter.
  
  
  RESULTS
  The 95th percentile for reflux parameters assessed in the distal/proximal oesophagus were: percent total time pH<4, 4.6/0.7%; percent upright time pH<4, 7.0/1.1%; percent supine time pH<4, 4.5/0.5%; number of reflux episodes, 73/12; number of reflux episodes with pH<4 for >5 minutes, 4/0; and the longest single acid exposure episode, 11.2/3.0 minutes.
  
  
  CONCLUSIONS
  Physiological gastroesophageal reflux occurs in healthy Chinese. These initial data provide a preliminary reference range that could be utilised by laboratories studying Chinese subjects.
authors.affiliation: Department of Medicine, The University of Hong Kong, Queen Mary Hospital, 102 Pokfulam Road, Hong Kong.
authors.forename: W H C
authors.initials: WH
authors.lastname: Hu
authors.forename: N Y H
authors.initials: NY
authors.lastname: Wong
authors.forename: K C
authors.initials: KC
authors.lastname: Lai
authors.forename: W M
authors.initials: WM
authors.lastname: Hui
authors.forename: K F
authors.initials: KF
authors.lastname: Lam
authors.forename: B C Y
authors.initials: BC
authors.lastname: Wong
authors.forename: H H X
authors.initials: HH
authors.lastname: Xia
authors.forename: C K
authors.initials: CK
authors.lastname: Chan
authors.forename: A O O
authors.initials: AO
authors.lastname: Chan
authors.forename: W M
authors.initials: WM
authors.lastname: Wong
authors.forename: K W T
authors.initials: KW
authors.lastname: Tsang
authors.forename: S K
authors.initials: SK
authors.lastname: Lam
mesh_terms: D000328:Adult; D044466:Asian People; D004947:Esophagus / Q000502:physiology*; D005260:Female; D005764:Gastroesophageal Reflux / Q000208:ethnology* / Q000503:physiopathology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory; D012016:Reference Values; D013270:Stomach / Q000502:physiology*