Non-invasive detection of gastro-oesophageal reflux using an ambulatory system.

The aim of this study was the separate measurement of reflux of food and acid into the oesophagus in 37 healthy, ambulant subjects. This was performed by radiolabelling the food and monitoring its reflux with a small directional gamma detector, which was placed externally over the oesophagus, and connected to an ambulatory data recorder. The pH was measured with a conventional oesophageal pH electrode. This method permitted the separate characterisation of acid and neutral (food) components of gastro-oesophageal reflux. The gastric emptying characteristics of the test meal were also monitored by gamma scintigraphy in a separate experiment. The oesophageal pH fell below 4 for 3.2 + 8.6/-2.3% (mean (SD)) of the recording time. Food reflux alone occurred for 17.8 + 53.2/-13.8% of the recording time. Simultaneous food and acid reflux occurred for only 0.95 + 5.2/-1.2% of the time. Not every reflux event detected by a fall in pH was seen as an increase in counts as a result of reflux of food, and vice versa. This poor correlation of food and acid reflux implies incomplete mixing of food and acid in the stomach, and further shows the inadequacy of reflux diagnosis methods that depend on pH detection alone.