Recommendations for long-term oesophageal pH monitoring.

Ambulatory 24-h pH monitoring in the distal oesophagus represents a widely accepted tool in the diagnosis of gastro-oesophageal reflux disease. When this method was first established, most attention was drawn to the definition of normal oesophageal pH values; various studies correlated morphological findings in the distal oesophagus with the extent of gastro-oesophageal reflux. We have compared different reflux-related variables under different measuring conditions; reflux time (percentage of time with pH below 4) was found to be much more reliable than variables derived from the recognition of single reflux episodes. The special advantage of long-term ambulatory pH monitoring is, however, in our opinion, its capacity for identifying gastro-oesophageal reflux as the primary cause of chest pain in those patients whose oesophagus has an endoscopically normal appearance. For this purpose, it is vital that the recording system be equipped with a reliable event marker; the oesophageal origin is confirmed by detection of a high coincidence between pain attacks and reflux episodes. The evaluation software for ambulatory pH monitoring must therefore allow for diagrammatic display of a complete 24-h recording where the onset of pain attacks is visible within the pH curve.