The 'artificial high pressure zone'. A non-invasive method to study in man the effect of the inhibitory innervation to the oesophagus. Validation study using a combined manometric--barostat technique.

OBJECTIVE: We previously developed a technique to study the effect of inhibitory innervation in the human oesophageal body, by creating an artificial high pressure zone (artificial HPZ) using an intra-oesophageal balloon. Swallowing provokes a fall in pressure in the artificial HPZ that precedes the peristaltic contraction. We aimed to prove that the swallow-induced fall in pressure in the artificial HPZ is due to relaxation of a segmental tonic contraction of the oesophageal wall at that level.

METHODS: Studies were performed in five healthy subjects. Oesophageal pressures were measured at 5, 10 and 15 cm above the lower oesophageal sphincter. A rubber balloon opposite the middle pressure sensor was used to induce the artificial HPZ. A barostat bag was glued to the opposite side of the balloon. The pressure in the barostat bag was pre-set at 8 mmHg below the pressure measured in the artificial HPZ. We studied deglutition-induced variations in the barostat bag volume after single and multiple swallows.

RESULTS: Immediately after single swallows and during multiple swallows, we observed a fall in pressure in the artificial HPZ and a significant increase in the barostat bag volume (254+/-67%) from 0.99 (0.37-1.93) to 3.74 (1.91-4.34) (P = 0.005) denoting oesophageal wall relaxation.

CONCLUSION: The swallow-induced fall in pressure in the artificial HPZ represents a real relaxation of a segmental tonic contraction of the oesophageal wall due to deglutitive inhibition. The oesophageal artificial HPZ is a simple method that can be used to study inhibitory phenomena in the body of the human oesophagus.