The effect of posture and pH on solid and liquid oesophageal emptying

Oesophageal emptying of solids and liquids has been assessed in normal subjects using radionuclide techniques. The solid bolus comprised a 10 g disc of cooked minced beef which was labelled with 160 microCi; 99m Tc macro-aggregated albumin (MAA). The liquid bolus consisted of 15 ml of water labelled with 300 microCi; 99m Tc. Studies were performed in the upright and supine positions and repeated after ingestion of 30 ml of 0.1 M HC1 diluted to pH 1.6. Solid and liquid assessments were performed separately with a scintillation camera positioned posteriorly. Subjects were instructed to swallow at the commencement of the test and at 15 s intervals subsequently, until the bolus entered the stomach. Oesophageal emptying in the supine position was significantly slower than emptying in the upright position. This was true for both solid and liquid emptying, in the neutral and in the acidified oesophagus. Emptying of a solid bolus did not appear to be influenced by oesophageal pH. However, emptying of a liquid bolus was significantly slower when the oesophageal pH was acid, for both the supine and upright positions. We conclude that the supine posture delays both liquid and solid oesophageal emptying. The presence of acid in the oesophagus at a pH of 1.6 delayed liquid emptying, but not solid emptying, from the oesophagus.