Objective: To test the effect of body position on oesophageal acid clearance time in patients with systemic sclerosis.
Design and methods: Fifteen consecutive patients with systemic sclerosis and six healthy subjects underwent oesophageal manometry and an acid clearance test in three body positions (supine, recumbent at 30 degrees and seated at 90 degrees) in randomized order.
Results: In healthy subjects the body position did not affect acid clearance time, whereas in patients the oesophagus cleared mainly by gravity. In patients the acid clearance time was significantly longer in the supine than in the seated position (P < 0.05). Nine patients did not have a detectable peristaltic wave in the distal oesophagus. In the other six oesophageal peristalsis was still detectable but contractions had reduced amplitude and often had double and triple peaks; also in this subgroup the acid clearance time recorded in the supine position was prolonged.
Conclusions: In systemic sclerosis gravity plays a major role in oesophageal acid clearance time. The finding of delayed acid clearance in a supine patient may suggest initial oesophageal involvement in the disease.