[Apnea Detection by Means of Respiratory Sound Recordings and Polysomnography - A Comparative Study]

Introduction In this study, recognition of apnoeas by means of polysomnography (PSG) and nocturnal respiratory sound recordings in patients with obstructive sleep apnoea (OSA) was analyzed and compared. Methods In 45 patients with OSA requiring treatment (AHI > 15/h), concomitant polysomnographic recordings and long term respiratory sound recordings by means of LEOSound were performed. Patients' average age was 58 ± 12 years (mean ± standard deviation), average BMI was 33 ± 7 kg/m². Audio-visual apnoea detection by LEOSound was compared to polysomnographic apnoea detection. Increased artifact rate due to dislocation of microphones led to rejection of 11 out of 45 recordings for detailed analysis. Results Comparison of apnea detection by audio-visual analysis and polysomnography yielded a median of 164 apneas for LEOSound recordings and 158 apneas for PSG. Median apnoea index (AI) was calculated to be 20/h for respiratory sounds recording and 21/h for PSG. The correlation of apnea indices from acoustic long term registration and PSG was 0.939 (p < 0.001). Discussion Acoustic long term registration of primary and secondary respiratory sounds is also capable to recognize apnoeas. Exact differentiation between apnoeas and hypopnoeas is only possible in a limited fashion.