Background--Gastro-oesophageal reflux disease (GORD) plays a major role in th development of Barrett's oesophagus However, it has yet to be elucidated what factors determine the length of Barrett' mucosa in each individual patient.
Aims--To determine if there is a correlation between oesophageal acid exposure and the length of Barrett's mucosa. W also compared the extent of oesophageal acid exposure between patients with short segment (SSBE) and long segment (LSBE) Barrett's oesophagus.
Methods--Twenty seven patients with Barrett's oesophagus were recruited prospectively into the study from the outpatient gastroenterology clinic at the Southern Arizona VA Health Care Sys. tem. Diagnosis of Barrett's oesophagus and its anatomical characteristics were determined during upper endoscopy. Ambulatory 24 hour oesophageal pH monitoring assessed the extent of oesophageal acid exposure.
Results--There was a significant correlation between per cent total time pH less than 4 and length of Barrett's mucosa (r=0.6234), p=0.0005). In addition, there was a significant correlation between per cent upright and supine time pH less than 4 and length of Barrett's mucosa (r=0.5847, p=.0014 and r=0.6265 p=0.0006, respectively). Patients with SSBE had significantly less oesophageal acid exposure than patients with LSBE, in terms of both per cent total time and per cent supine time pH less than 4 (p[less than]O.05).
Conclusions--The length of Barrett's mucosa correlated with the duration of oesophageal acid exposure. Patients with LSBE experienced significantly more oesophageal acid exposure than patients with SSBE. Duration of oesophageal acid exposure appears to be an important contributing factor in determining the length of Barrett's mucosa.
Keywords: Barrett's oesophagus; intestinal metaplasia; esophageal pH monitoring; oesophageal acid exposure
The diagnosis of Barrett's oesophagus hinges n the presence of intestinal metaplasia that replaces the normal stratified squamous epthelium of the oesophagus.  Barrett's oesophagus has attracted much attention because of its potential for the development of adenocarcinoma of the oesophagus. Currently, this tumour is the fastest rising cancer in the USA. [2 3]
Reflux of gastric content into the oesophagus has been suggested to be responsible for the development of Barrett's epithelium. In patients presenting with gastro-oesophageal reflux symptoms, 12% were found to have Barrett's oesophagus  The prevalence is markedly higher in patients with erosive oesophagitis (36%)  Furthermore, patients with Barrett's oesophagus tend to have relatively higher oesophageal acid exposure compared with normal subjects, patients with non-erosive reflux disease, or those with erosive oesophagitis.  Fitzgerald et al have recently shown that short pulses of acid exposure increased cell proliferation of Barrett's epithelium ex vivo while continuous acid exposure induced differentiation and reduced proliferation.  This study also demonstrated that the effects of acid exposure are pH dependent as well as time dependent.
Use of antireflux medications in patients with gastro-oesophageal …