Analysis of snoring to determine the site of obstruction in obstructive sleep apnea syndrome

Background The aim of this study was to integrate the physical findings of drug-induced sleep endoscopy with snoring sound analysis in patients with obstructive sleep apnea/hypopnea syndrome (OSAS) and to compare the findings with previously published data. Methods This was a prospective, non-randomized study. Participants were all candidates for surgical treatment of OSAS and formed three groups, retropalatal (RP) obstructions, retrolingual (RL) obstructions, and multilevel (ML) obstructions. At the time of DISE, recordings of concurrent snoring sounds were made. Mean pitch frequency, peak sound frequency, and fundamental frequency (Fo) components were determined. Results A total of 55 participants had mean age 46.2 ± 7.3 years, mean BMI 30.0 ± 3.7 kg/m 2 , and included 11 women (20%). Differences in mean pitch frequency, Fo, and peak sound frequency were all statistically significant between the RP and RL ( p = 0.001), between ML and RL ( p = 0.025) but were not significantly different between RP and ML. Mean pitch frequency of RP was lower than RL, and ML frequency was between RL and RP. The sound analysis graphics revealed RP waves with sharp peaks and lower frequencies and RL with smooth curves and higher frequencies. ML showed irregular patterns. Mean pitch frequency of RL was always above 400 Hz, whereas RP was below this value. Conclusions It is feasible to apply sound analysis to determine the site of obstruction during DISE. Combining the data may help surgeons make more accurate assessments of the pattern of the disease.