Mechanisms of nocturnal gastroesophageal reflux events in obstructive sleep apnea
Esophageal pH has been studied at night in six healthy subjects. A pH electrode was placed 5 cm above the low esophageal sphincter and sleep state was monitored. The subjects were connected to the recording devices during two nights, but the recording was performed only during the second night. A pH drop superior to 2 units and lasting longer than 30 sec was estimated as a gastro-esophageal reflux (GER). GER episodes were determined from beginning of sleep to definite waking. Ten GER appeared in four of the six subjects. They occurred both during transient arousals or complete wakefulness, but never in NREM or REM sleep. These results are consistent with those previously reported in normal subjects. On the contrary, GER were reported during REM sleep or NREM sleep in 'near miss' sudden infant death infants and in asthmatic children. Thus, the dysfunction of the esophagus might be considered either as the origin of the diseases, or as one of their consequences.