Mechanisms of gastro-oesophageal reflux in the lateral decubitus positions.

Gastro-oesophageal reflux is more common in the right than in the left lateral position but the reasons why are not well understood. We have therefore studied the mechanisms underlying reflux in the lateral decubitus positions in patients with reflux disease. Fifteen patients with symptomatic reflux and excessive oesophageal acid exposure were studied (nine male, age 25-63 years). Each was intubated with a perfused manometric assembly, incorporating a Dent sleeve, and a pH probe. Following a 30-min basal period, a 400-kCal meal was infused into the stomach and patients were studied for 60 min in each lateral position. Following infusion of the meal, lower oesophageal sphincter (LOS) pressure fell and transient LOS relaxation (TLOSR) frequency increased. Acid reflux episodes were more common in the postprandial period (fasting 0 (0-6) h, first postprandial hour 1 (0-9) h, P = 0.0002, second postprandial hour 1 (0-22) h, P = 0.02) and occurred more than twice as often in the right lateral position (right 3 (0-22) h, left 0 (0-10) h, P = 0.01). However, TLOSRs, swallow-related relaxations and low basal LOS pressures were equally common in both lateral positions. In patients with reflux disease, postprandial reflux is twice as common in the right lateral position. This does not relate to differences in gastro-oesophageal junctional pressure, suggesting that other aspects of barrier function or differences in the intragastric distribution of chyme may be important.