Proximal migration of esophageal acid perfusions during waking and sleep

OBJECTIVE: Proximal acid migration resulting from gastroesophageal reflux h as been implicated in aerodigestive complaints and disorders. This study wa s 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. Esop hageal acid perfusions of 1 ml and 3 ml were accomplished at a site 5cm abo ve 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 pr oximal esophagus at 10 and 15 cm above the lower esophageal sphincter. RESULTS: Acid volume clearly increased the incidence of migration to the mi d 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 migr ation 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 significa ntly longer during sleep as measured by the mid- and proximal esophageal pH sensors. CONCLUSIONS: In healthy individuals, volume enhances the likelihood of migr ation to both mid- and proximal esophagus, and significantly prolongs clear ance time in the waking state. Posture appears to be a less significant par ameter with regard to both the incidence of acid migration and acid clearan ce. Sleep is a significant risk factor for acid migration to the proximal e sophagus for even minute volumes, and markedly prolongs acid clearance.