MECHANISMS OF GASTROESOPHAGEAL REFLUX IN AMBULANT HEALTHY-HUMAN SUBJECTS

Background/Aims: Investigation of the motor events underlying gastroes ophageal reflux has largely been confined to resting, recumbent subjec ts. The motor events associated with reflux during physical activity r emain unknown. The aim of this study was to investigate the patterns o f lower esophageal sphincter (LES) function underlying reflux in healt hy 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 pres sure in the stomach, esophagus, and pharynx, and pH was recorded 5 cm above the LES. Signals were stored in a portable data-logger. Recordin gs were made for 24 hours, including moderate physical activity, perio ds of rest and sleep, standardized meals, and standardized exercise. R esults: Most reflux episodes (81 of 123; 66%) occurred in the 3 hours after food intake; only 2 episodes occurred during exercise. LES press ure was less than or equal to 3 cm H2O in 79% of reflux episodes. Tran sient LES relaxation was the mechanism of reflux in 82% of episodes, i rrespective of activity or body position, whereas swallow-related LES relaxations accounted for 13% and persistently absent LES pressure acc ounted for 1%. Straining occurred in only 20% of episodes. Conclusions : In ambulant healthy subjects, accurate continuous recording of LES f unction is possible, reflux usually occurs during transient LES relaxa tions, and straining is not a major factor in the induction of reflux.