Responses to gastric distension in functional dyspepsia

Abstract

Background: Studies have shown that an altered visceral perception threshold plays a role in the pathogenesis of upper gastrointestinal tract symptoms in dyspeptic patients. However, it is not clear whether the compliance and adaptive relaxation of the proximal stomach contribute to the symptoms.

Aims: To investigate whether abnormal relaxation or adaptation of the proximal stomach during the interdigestive state and the postprandial phase could explain the symptoms of functional dyspepsia.

Subjects: Twelve volunteers and 12 patients with dysmotility-like functional dyspepsia were included in the study.

Methods: An electronic barostat was used to investigate adaptation to distension of the proximal stomach and accommodation in response to a liquid meal. Dyspeptic symptoms during distension and accommodation were assessed.

Results: When the subjects were in the fasting state, the pressure-volume curve showed slightly higher compliance in the dyspeptic patients (p < 0.05). Patients not only had a higher score for nausea, bloating, and pain but also the increase in nausea and pain scores with intragastric pressure was higher than in volunteers (p < 0.05). The increase in intragastric bag volume in response to a meal was significantly lower in patients (p < 0.05). Both bloating and pain significantly increased in the patients (p < 0.05), but not in the healthy volunteers.

Conclusions: Patients with functional dyspepsia show slightly higher compliance to mechanical distension. Their visceral perception of mechanical stress is enhanced. In contrast with the balloon distension, relaxation after a meal was less. Therefore the postprandial symptoms cannot be explained fully by greater global tension in the stomach wall, as assessed by the barostat technique. Visceral hypersensitivity plays a major role in the pathogenesis of the symptoms.

Figure 1

Mean volume-pressure curve in the dyspeptic patients and healthy volunteers. The inflation (ascending part of the pressure-volume) curve showed a significantly steeper slope (p<0.05) in the dyspeptic patients than in the controls, indicating a higher compliance in the dyspeptic patients. The descending part of the pressure-volume curve (deflation) showed a delay in the return of the gastric volume toward the values at minimal distending pressure (MDP) (hysteresis).

Figure 2

Example of a postprandial relaxation curve in a healthy volunteer. Baseline volume was measured at minimal distending pressure + 1 mm Hg. After the meal there was an increase in gastric bag volume to a maximum. The volume returned to the baseline value within 80 minutes.

Figure 3

Mean postprandial relaxation curves in the dyspeptic patients and healthy volunteers. The increase in intragastric bag volume in the dyspeptic patients was significantly lower than that in the healthy volunteers (p<0.05). The time interval between the start of ingestion of the meal and the time at which the maximum volume was reached was significantly shorter in patients than in controls (p<0.01).

Figure 4

Nausea, bloating, and pain scores in relation to the gastric bag pressure above the minimal distending pressure (MDP) in dyspeptic patients and healthy volunteers. There was a significantly greater increase in nausea and pain scores with increasing pressure in the patients than in the healthy volunteers (p<0.05, p<0.01).

Figure 5

Nausea, bloating, and pain scores after the test meal in dyspeptic patients and healthy volunteers. After the meal, the dyspeptic patients had significantly more nausea, bloating, and pain than the healthy volunteers (p<0.05, p<0.05, p<0.05 respectively). The patients showed a significant increase in bloating and pain scores (p<0.05, p<0.04).

Figure 6

Individual nausea, bloating, and pain scores 10 minutes after the test meal plotted against relaxation volume. Postprandial symptoms are not related to volume.