MECHANISMS OF GASTROESOPHAGEAL REFLUX IN AMBULANT HEALTHY-HUMAN SUBJECTS

Background/Aims: Investigation of the motor events underlying gastroesophageal reflux has largely been confined to resting, recumbent subjects. The motor events associated with reflux during physical activity remain unknown. The aim of this study was to investigate the patterns of lower esophageal sphincter (LES) function underlying reflux in healthy subjects and the effect of exercise and physical activity on reflux mechanisms. Methods: LES pressure was recorded with a perfused sleeve sensor in 10 healthy subjects; intraluminal transducers recorded pressure in the stomach, esophagus, and pharynx, and pH was recorded 5 cm above the LES. Signals were stored in a portable data-logger. Recordings were made for 24 hours, including moderate physical activity, periods of rest and sleep, standardized meals, and standardized exercise. Results: Most reflux episodes (81 of 123; 66%) occurred in the 3 hours after food intake; only 2 episodes occurred during exercise. LES pressure was less than or equal to 3 cm H2O in 79% of reflux episodes. Transient LES relaxation was the mechanism of reflux in 82% of episodes, irrespective of activity or body position, whereas swallow-related LES relaxations accounted for 13% and persistently absent LES pressure accounted for 1%. Straining occurred in only 20% of episodes. Conclusions: In ambulant healthy subjects, accurate continuous recording of LES function is possible, reflux usually occurs during transient LES relaxations, and straining is not a major factor in the induction of reflux.