Airway pH monitoring in patients with suspected obstructive sleep apnoea using the Dx-pH oropharyngeal probe: preliminary report of a prospective cohort study

To investigate the laryngopharyngeal reflux (LPR) episodes and pH values in patients with suspected obstructive sleep apnoea (OSA) using the Dx-pH oropharyngeal probe.Prospective cohort study.Tertiary medical centre.Forty patients with complaint of snoring or suspected OSA were prospectively enrolled to receive full nocturnal polysomnography (PSG). The patients were divided into 2 groups: a simple snorers group if the Respiratory Disturbance Index (RDI) was < 5 and an OSA group if the RDI was ≥ 5.The patients simultaneously received Dx-pH oropharyngeal probe monitoring for 12 h from about 6 pm to 6 am of the next day. The number of LPR events was recorded if the nadir of rapid pH drops was below pH 5.0 and 5.5. The difference of LPR events between the two groups and the difference of LPR events between awake and sleep periods in each group were analysed, respectively.There were 18 (45\%) patients diagnosed as OSA with a mean RDI of 28.7, and 22 patients (55\%) diagnosed as simple snorers. Between 2 groups, there were no significant differences in the LPR events and pH values during the awake period, sleep period or overall recording period. Comparison of the LPR events and minimum pH values between the awake period and the sleep period revealed there were no significant differences in either group.Using the new sensitive Dx-pH oropharyngeal probe with PSG, we found that OSA does not correlate with a higher incidence of LPR episodes.