Does body posture affect the incidence and mechanism of gastro-oesophageal reflux?

We studied eight patients with gastro-oesophageal reflux disease to compare the frequency and mechanism of reflux in the upright and supine positions. Simultaneous oesophageal manometry and pH studies were performed on two separate days in each subject in the fasting and postprandial periods. The frequency of reflux tended to be higher in the upright position. The most prevalent mechanism of reflux in either position was transient relaxation of the lower oesophageal sphincter. The frequency of transient lower oesophageal sphincter relaxation was higher in the upright than in the supine position. There was no difference in the total reflux time, acid clearance time, and number of reflux episodes lasting longer than five minutes in the two positions. We suggest that daytime reflux (upright) may be as important as night time (supine) reflux in the pathogenesis of reflux oesophagitis and needs to be considered when treating patients with reflux disease.