title: A Study to Draw a Normative Database of Laryngopharynx pH Profile in Chinese.
abstract: OBJECTIVE
  To draw a normative database of laryngopharynx pH profile in Chinese subjects.
  
  
  METHODS
  Normal volunteers were recruited from "www.Ganji.com" and People's hospital between May 2008 and December 2009. The Restech pH Probes were calibrated in pH 7 and pH 4 buffer solutions according to the manufacturer's instructions. Each volunteer was asked to wear the device for a 24-hour period and was encouraged to participate in normal daily activities.
  
  
  RESULTS
  The healthy volunteers consisted of 20 males and 9 females with a median age of 23 years (interquartile range, 21 to 32 years). The 95th percentiles for % total times at pH < 4, pH < 4.5, pH < 5.0 and pH < 5.5 for the oropharynx pH catheter were 0.06%, 1.01%, 7.23% and 27.34%, respectively. The 95th percentile for number of reflux events within the 24-hour period at pH < 4, pH < 4.5, pH < 5.0 and pH < 5.5 were 2.0, 18.0, 107.5 and 284.5, respectively.
  
  
  CONCLUSIONS
  This is the first study to systematically assess the degree of reflux detected by the new pH probe in healthy asymptomatic Chinese volunteers and to report normative values in Chinese people. Using an oropharyngeal pH catheter to monitor laryngopharyngeal reflux indicated that in healthy Chinese, reflux should be considered normal if the percent time at pH less than 4.5 is no more than 1%.
authors.affiliation: Departments of Gastroenterology, Peking University People's Hospital, Beijing, China.
authors.forename: Guijian
authors.initials: G
authors.lastname: Feng
authors.affiliation: Departments of Gastroenterology, Peking University People's Hospital, Beijing, China.
authors.forename: Junyao
authors.initials: J
authors.lastname: Wang
authors.affiliation: Departments of Otorhinolaryngology , Peking University People's Hospital, Beijing, China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Departments of Gastroenterology, Peking University People's Hospital, Beijing, China.
authors.forename: Yulan
authors.initials: Y
authors.lastname: Liu
keywords: Esophageal pH monitoring, Gastroesophageal reflux, Laryngopharyngeal reflux