Ambulatory 24-hour oesophageal pH monitoring in normal subjects: a multicentre study in Italy. G.I.S.M.A.D. GOR Study Group.

A multicentre study was performed in Italy in order to establish normal values for acid gastro-oesophageal reflux. In 73 healthy subjects 24-hour oesophageal pH measurements were carried out under standardized conditions. The hourly number of reflux episodes and oesophageal acid exposure was assessed and analyzed by means of a computerized system. The distribution frequency of both parameters was skewed to the left, thus exhibiting a non-normal pattern. Acid reflux was lowest during the night and highest after meals. The oesophageal acid exposure and the number of reflux episodes were correlated both over 24 hours and in the subsets studied. A good agreement was found with data from previous reports. Our findings should be helpful in establishing a data base for physiological gastro-oesophageal reflux.