NEW ORLEANS — Sleep apnea and hypoxia are rarely associated with gastroesophageal reflux and probably are not important causes of increased acid exposure, Anthony DiMarino Jr., M.D., reported at the annual Digestive Disease Week.
“The cause of nocturnal acid reflux events is presumably due to transient lower esophageal sphincter relaxation,” said Dr. DiMarino, chief of the division of gastroenterology and hepatology at Thomas Jefferson University Hospital, Philadelphia. “It is not related to nocturnal respiratory changes of apnea or hypoxia.”
He and his associates studied 16 patients with self-described insomnia on two separate nights in the Jefferson Sleep Disorders Center using simultaneous polysomnography and esophageal pH monitoring. The researchers noted each episode of sleep apnea, central sleep apnea, obstructive sleep apnea, hypopnea, hypoxia, and awakening (a period of wakefulness lasting for at least 15 seconds), and determined their relationship with gastroesophageal reflux events.
A decrease in the esophageal pH below 4·0 was considered a significant reflux event. Reflux events were associated with arousals if they occurred 5 minutes prior to the sleep event.
The average age of patients was 41·3 years and their mean body mass index was 25 kg/m2. Ten of the 16 patients were men.
The researchers recorded 240 apnea episodes, of which 13 were associated with reflux. Of the 27 obstructive apnea episodes, 1 was associated with reflux.
“The majority of reflux events were not associated with apnea, and there was no consistent relationship of the reflux events to the type of apnea or hypopnea,” Dr. DiMarino said.
The researchers recorded 44 hypoxia events, of which 9 were associated with reflux. In addition, there were 61 awakenings associated with the 240 apnea episodes, and 27 awakenings associated with the 44 hypoxia events. This suggests that sleep awakenings are related to apnea and hypoxia, but they do not cause reflux as a secondary event, he said.