Influence of body posture on intestinal transit of gas. (Neurogastroenterology).

Background: Patients describe that body posture may affect their abdominal bloating, distension, and flatulence, but whether changes in position have objectively demonstrable effects, either beneficial or deleterious, has not been investigated.

Aim: To determine the effect of body posture, upright versus supine, on intestinal transit of gas loads.

Methods: In each subject a gas mixture was continuously infused into the jejunum (12 ml/min) for three hours, and gas evacuation, clearance of a non- absorbable gaseous marker, perception, and abdominal girth were measured. Paired studies were randomly performed in each subject on separate days in the upright and supine positions.

Subjects: Eight healthy subjects without gastrointestinal symptoms.

Results: In the upright position, intestinal gas retention was much smaller than when supine (13 (52) ml v 146 (75) ml retention at 60 minutes, respectively; p<0.05), and clearance of the gas marker was expedited (72 (10)% clearance v 49 (16)% at 60 minutes, respectively; p<0.05). The gas challenge test was well tolerated both in the upright and supine positions without abdominal distension.

Conclusion: Body posture has a significant influence on intestinal gas propulsion: transit is faster in the upright position than when supine.

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Patients with irritable bowel syndrome and functional bloating frequently report that abdominal symptoms, such as bloating and distension that they attribute to intestinal gas, develop progressively during the day and tend to resolve with bed rest. (1) However, the effect of body posture on intestinal gas transit and evacuation has not been investigated.

As gas within the abdominal cavity tends to float and rise to the top, theoretically caudal gas progression would be facilitated in the supine position. Hence we hypothesised that intestinal gas transit and evacuation are enhanced in the supine compared with the upright position. Using a new technique developed in our laboratory, (2) we compared the effect of body posture, upright versus supine, on gas transit.

MATERIAL AND METHODS

Participants

Eight healthy individuals (three women and five men; age range 21-28 years) participated in the study after giving written informed consent. Subjects completed a pre-entry questionnaire to determine the absence of gastrointestinal symptoms, particularly symptoms of constipation, (1) difficult gas evacuation, feeling of excessive abdominal gas, or excessive gas evacuation. The protocol for the study had been previously approved by the Institutional Review Board of the University Hospital Vall d'Hebron.

Gas transit test

Jejunal gas infusion

We used a polyvinyl tube assembly (4.1 mm OD) that incorporated a gas infusion channel (2.0 mm ID) with multiple side holes scattered over the distal 2 cm segment. Gas was continuously infused into the proximal jejunum at 12 ml/min, using a modified volumetric pump (Asid Bonz PP 50-300; Lubratronics, Unterschleissheim, Germany). We infused a gas mixture containing 88% nitrogen, 6.5% carbon dioxide, and 5.5% oxygen, bubbled into water for saturation, that mimicked …