[Physiological reflux in proximal esophagus (assessment with simultaneous pH monitoring in proximal and distal esophagus in healthy subjects].

Two-level pH monitoring was performed for 24 hours in 20 healthy subjects to document the presence of reflux episodes and to obtain reference values for reflux studies. The pH probes were placed 5 and 20 centimetres above the LES by means of a manometric technique. Significant differences were found at these two levels. At the proximal esophageal level 18 of the 20 subjects had reflux episodes. Five centrimetres above the lower esphageal sphincter the total reflux time was 1.35%, 2.05% in the upright and 0.15% in the supine positions. At 20 centimetres level it was significantly lower: 0.5% the total percent time with pH below 4, 0.8% and 0% in the upright and supine positions respectively. The mean reflux time was about 40% of the distal value, but the same pattern of reflux was observed at two levels of the esophagus. This technique is useful in documenting the cephalad extend of GER and allows to identify normal GER patterns at different levels of the esophagus.