title: 24-H pharyngeal pH monitoring in healthy volunteers: a normative study.
abstract: BACKGROUND
  Gastropharyngeal reflux has been associated with disorders of the upper and lower airways. It may be shown by pharyngeal pH-metry, but reports on normality in healthy volunteers are scarce. No definite consensus has been reached considering the upper limit of normality (ULN). The aim of the present study was therefore to quantify the occurrence of pharyngeal acid exposure (pH < 4) in healthy volunteers and, further, to examine its relation to acid exposure of the oesophagus and oesophageal motility and its occurrence in relation to age, sex, and body position.
  
  
  METHODS
  Forty healthy volunteers underwent ambulatory 24-h pH-metry, using antimony electrodes positioned 2 cm above the upper oesophageal sphincter and 5 cm above the lower oesophageal sphincter on the basis of manometry. Technical artefacts were excluded before calculation of all results.
  
  
  RESULTS
  Gastropharyngeal reflux occurred in most healthy volunteers without any significant relation to age, sex, or body weight. Pharyngeal acid reflux occurred mainly in the upright position. The ULN for pharyngeal acid exposure time was assessed to 0.9% (0.2% after exclusion of mealtimes). The ULN for the number of acid events in the pharynx was 18 (6.1). The corresponding ULNs for the oesophagus were 7% and 84.
  
  
  CONCLUSIONS
  Gastropharyngeal reflux may be effectively monitored by ambulatory pH-metry. The present study provides reference limits, a prerequisite for evaluating the pathophysiologic importance of the phenomenon.
authors.affiliation: Dept. of Otorhinolaryngology, Head and Neck Surgery, NAL Hospital, Trollhättan, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Bove
authors.forename: M
authors.initials: M
authors.lastname: Ruth
authors.forename: L
authors.initials: L
authors.lastname: Cange
authors.forename: I
authors.initials: I
authors.lastname: Månsson
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008365:Manometry; D008875:Middle Aged; D018670:Monitoring, Ambulatory; D010614:Pharynx / Q000378:metabolism*; D011187:Posture; D012016:Reference Values