Abstract: Objective Patients with obstructive sleep apnea and hypopnea syndrome(OSAHS)often have a high incidence of laryngopharyngeal reflux, the purpose of this study was to investigate the characteristics of nocturnal alkali reflux in OSAHS patients. Methods The results of oropharyngeal pH monitoring and simultaneous polysomnography in 98 patients with snoring were analyzed retrospectively. The correlation between abnormally high pH events with pH >7.5 and severity of sleep ventilation disorders was analyzed. Saliva samples were reserved in the morning for trypsin detection by enzyme-linked immunosorbent assays. Results Oropharyngeal pH monitoring results found 33 cases with high pH events(pH >7.5)during nocturnal sleep. The occurrence of high pH events in the OSAHS group was 39.0%(32/82), which was significantly higher than the pure snoring group(6.3%, 1/16)(P=0.011), and similar results were seen with the percentage time of high pH events and the highest pH values(P=0.020, 0.020). Mean salivary trypsin levels were 27.42-401.44 μg/L, of which 17 cases were abnormally increased(275.28±59.13)μg/L. There was no significant difference between the OSAHS and pure snoring groups in trypsin content, but the trypsin content in the 32 OSAHS patients with high pH events differed statistically based on the degree of snoring(P=0.048). Conclusion OSAHS patients were prone to nocturnal high pH events, as revealed through oropharyngeal pH monitoring and abnormally increased saliva trypsin contents in the morning, suggesting that alkaline reflux may occur. However, the mechanisms of alkaline reflux need to be further studied.

Key words: Laryngopharyngeal reflux, Alkali reflux, Obstructive sleep apnea hypopnea syndrome, Dx-pH monitoring, Trypsin