title: The fractal nature of human gastro-oesophageal reflux.
abstract: BACKGROUND
  We are unaware of the analyses of time series data resulting from 24 h recordings of human gastric or oesophageal pH. As a result, we have no understanding of the quantitative changes in gastric or oesophageal acidity over time, the patterns that might characterize these changes, or the physiological significance of gastro-oesophageal reflux.
  
  
  OBJECTIVE
  To examine the time series for gastric and oesophageal pH.
  
  
  METHODS
  Detrended fluctuation analysis and lag analysis were used to analyse data from 24 h recordings of oesophageal and gastric pH in five normal subjects and five subjects with gastro-oesophageal reflux disease.
  
  
  RESULTS
  Analyses of the patterns of gastric and oesophageal pH over time in normal subjects and subjects with gastro-oesophageal reflux disease indicate that the fluctuations in pH are self-similar across different time scales and are consistent with an underlying fractal process. Furthermore, there is a significant statistical association between sequential pH values separated by as much as 2.2 h.
  
  
  CONCLUSIONS
  We hypothesize that the self-similar, fractal pattern encodes information about gastric acidity and that the oesophagus decodes this information and, when appropriate, may signal the stomach to reduce gastric acidity. Subjects with gastro-oesophageal reflux disease might have an impaired oesophageal-gastric feedback mechanism that results in increased gastric acid, which reflux from the stomach into the oesophagus.
authors.affiliation: Science for Organizations, Inc., Chatham, NJ 07928, USA. gardnerj@scifororg.com
authors.forename: J D
authors.initials: JD
authors.lastname: Gardner
authors.forename: W
authors.initials: W
authors.lastname: Young
authors.forename: S
authors.initials: S
authors.lastname: Sloan
authors.forename: M
authors.initials: M
authors.lastname: Robinson
authors.forename: P B
authors.initials: PB
authors.lastname: Miner
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004947:Esophagus / Q000503:physiopathology*; D005260:Female; D017709:Fractals; D005745:Gastric Acidity Determination; D005764:Gastroesophageal Reflux / Q000503:physiopathology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D013270:Stomach / Q000503:physiopathology*; D013997:Time Factors