Study objectives: To investigate whether distal esophageal acidification occurs during sleep in patients suspected of sleep-disordered breathing, and whether such acidification is related to respiratory abnormalities.
Design and patients: Fourteen middle-aged, snoring men all complaining of daytime sleepiness and suspected of having obstructive sleep apnea.
Setting: Sleep laboratory, Pulmonary Department, Landspitali University Hospital, Reykjavik, Iceland.
Measurements and results: Each patient underwent full nocturnal polysomnography testing, which included continuous monitoring of esophageal pressure (Pes) and pH. We identified all pH events, which were defined as a reduction in esophageal pH of ≥ 1.0. During each pH event, the respiratory recordings where examined for the presence of apneas or hypopneas, and Pes was recorded. The data were analyzed to determine the possible relationships between pH events and respiratory events, and between changes in pH and changes in Pes. We found that there were more respiratory events than pH events. The mean (± SD) number of apneas and hypopneas per hour of sleep was 33 ± 22, whereas the mean number of pH events per hour of sleep was 7 ± 6. Overall, 81% of all pH events were associated with respiratory events. Correlation analysis did not reveal any significant relationship between pH events and the magnitude of Pes or apnea-hypopnea index.
Conclusions: Episodes of esophageal acidification are common in patients with sleep apnea, and are usually associated with respiratory and pressure events. However, changes in pH were independent of the magnitude of the Pes.