Objective: Proximal acid migration resulting from gastroesophageal reflux has been implicated in aerodigestive complaints and disorders. This study was designed to investigate the effects of acid volume, posture, and sleep on proximal esophageal acid migration (drop in pH to <4.0).
Methods: The study was performed in 15 healthy adults. A distal esophageal acid perfusion technique to simulate gastroesophageal reflux was used. Esophageal acid perfusions of 1 ml and 3 ml were accomplished at a site 5 cm above the proximal border of the lower esophageal sphincter in the upright and supine positions during waking, and during polysomnographically monitored sleep. Esophageal pH was recorded by two sensors located in the mid- and proximal esophagus at 10 and 15 cm above the lower esophageal sphincter.
Results: Acid volume clearly increased the incidence of migration to the mid and proximal sensors during both waking and sleep, and also significantly increased acid clearance time. Posture failed to significantly affect the incidence of acid migration and acid clearance. Sleep clearly enhanced migration to the proximal pH sensor of even those perfusions as small as 1 ml. For instance, 40% of 1 ml perfusions during sleep migrated to the proximal sensor compared with <1% during waking. Acid clearance times were significantly longer during sleep as measured by the mid- and proximal esophageal pH sensors.
Conclusions: In healthy individuals, volume enhances the likelihood of migration to both mid- and proximal esophagus, and significantly prolongs clearance time in the waking state. Posture appears to be a less significant parameter with regard to both the incidence of acid migration and acid clearance. Sleep is a significant risk factor for acid migration to the proximal esophagus for even minute volumes, and markedly prolongs acid clearance.