Arousal in patients with gastro-oesophageal reflux and sleep apnoea

Nocturnal gastro-oesophageal reflux has been observed in patients with obst ructive sleep apnoea (OSA). Negative intrathoracic pressure during apnoeas and arousal have been suggested as the underlying mechanisms. In order to evaluate this hypothesis, the coincidence and sequence in time of arousal, apnoea and reflux events were analysed. Fifteen patients with O SA or heavy snoring were studied by means of standard polysomnograpy with p arallel recording of 24-h oesophageal pH. Reflux events during the day were present in all patients, five of whom had symptoms of reflux. In three of these and in five other patients, a total of 69 nocturnal reflux events were found. In 68 events, arousal was found w ith the reflux event. Only one reflux without arousal was found (sleep stag e 2). Seventeen events occurred during wakefulness after sleep onset. The p ercentage of time with a pH of <4 during wakefulness after sleep onset was significantly higher than the percentage of time with a pH of <4 during tot al sleep time (p<0.05). In 37 of the 52 reflux events which occurred during sleep, either an apnoea or a hypopnoea was found prior to the event. The i nvestigation of sequence in time did not prove a causal relation between re spiratory events and reflux events. The results indicate that gastro-oesophageal reflux and obstructive sleep a pnoea are two separate disorders, which both have a high prevalence in obes e patients.