Mechanism of gastroesophageal reflux in patients with obstructive sleep apnea syndrome.

BACKGROUND: It has been reported that the prevalence of gastroesophageal reflux (GER) disease is high in patients with obstructive sleep apnea (OSA). End-inspiratory intra-esophageal pressure decreases progressively during OSA, which has been thought to facilitate GER in OSA patients. The aim of our study was to clarify the mechanisms of GER during sleep (sleep-GER) in OSA patients. METHODS: Eight OSA patients with reflux esophagitis (RE), nine OSA patients without RE, and eight healthy controls were studied. Polysomnography with concurrent esophageal manometry and pH recording were performed. KEY RESULTS: Significantly more sleep-GER occurred in OSA patients with RE than without RE or in controls (P < 0.05). The severity of OSA did not differ between OSA patients with RE and without RE. Sleep-GER was mainly caused by transient lower esophageal sphincter relaxation (TLESR), but not by negative intra-esophageal pressure during OSA. During OSA gastroesophageal junction pressure progressively increased synchronous to intra-esophageal pressure decrease. OSA patients had significantly more TLESR events during sleep related to preceding arousals and shallow sleep, but the number of TLESR events was not related to RE. CONCLUSIONS & INFERENCES: In OSA patients, sleep-GER was mainly caused by TLESR, but not by negative intra-esophageal pressure due to OSA.