Determinants of gastro-oesophageal reflux and their inter-relationships.

Gastro-oesophageal reflux was measured by 24-h ambulatory oesophageal pH monitoring in 220 patients with symptoms suggestive of gastro-oesophageal reflux disease. By multiple regression analysis it was found that the pressure in the distal oesophageal high pressure zone, the presence of a hiatal hernia, the intra-abdominal length of the high pressure zone, the amplitude of the contraction waves in the distal oesophagus and age all significantly participated in the determination of the amount of gastro-oesophageal reflux. The pressure in the distal oesophageal high pressure zone was the single variable that correlated most strongly to the amount of reflux. Although the amount of reflux increased significantly with increasing weight as measured by Broca's index, this variable did not participate in the determination of reflux by the multiple regression test. The study emphasizes the role of the pressure and intra-abdominal length of the distal oesophageal high pressure zone as the primary antireflux barrier. It also shows that a hiatal hernia plays a role in generating gastro-oesophageal reflux through a mechanism other than affecting the pressure and the intra-abdominal length of the high pressure zone.