The fractal nature of human gastro-oesophageal reflux.
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.
Gardner
J D
JD
Science for Organizations, Inc., Chatham, NJ 07928, USA. gardnerj@scifororg.com
Young
W
W
Sloan
S
S
Robinson
M
M
Miner
P B
PB
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