Soltanzadeh R, Moussavi Z
Annu Int Conf IEEE Eng Med Biol Soc. 2015;2015:2231-4. doi: 10.1109/EMBC.2015.7318835.
Upper airway structure is known to be affected in individuals with obstructive sleep apnea (OSA). In this pilot study, we investigated whether the changes of upper airway resistance (UAR) within a breathing phase, estimated from tracheal breathing sounds and airflow, is a predictor of OSA severity. Tracheal breathing sounds and airflow of 15 individuals in three groups of mild, moderate and severe OSA during wakefulness, recorded in supine position, were used in this study. The grouping of the study subjects were done based on their apnea/hypopnea index (AHI) per hour, prospectively. The breathing sounds and airflow were recorded simultaneously with full overnight polysomnography (PSG) assessment. The sounds of 3 noise-free breathing cycles were extracted and sequestered into inspiratory and expiratory phase segments manually for each study subject. The power spectra of the sound signals of each respiratory phase were calculated in 15ms windows with 50% overlap between adjacent windows. The UAR was then estimated as the ratio of the energy of power spectrum of each window within 100 to 2500 Hz, and its corresponding airflow. Then, the variance of the short-time windows' UAR, Var(UAR) during each respiratory phase was calculated. The ratio of the Var(UAR) in logarithmic scale between inspiration and expiration was found to be significantly different (p<;0.01) between the three OSA groups; also it was found to be highly correlated with AHI. These results are congruent with the hypothesis that the upper airway patency is not kept constant in OSA population, and suggest the change in acoustic UAR during wakefulness maybe considered as a predictor of OSA.
已知阻塞性睡眠呼吸暂停（OSA）患者的上呼吸道结构会受到影响。在这项初步研究中，我们调查了根据气管呼吸音和气流估计的呼吸阶段内上呼吸道阻力（UAR）变化是否是OSA严重程度的预测指标。本研究使用了15名处于清醒状态的轻度、中度和重度OSA三组患者仰卧位时的气管呼吸音和气流，这些数据是在仰卧位记录的。研究对象的分组是根据他们每小时的呼吸暂停/低通气指数（AHI）前瞻性进行的。呼吸音和气流与整夜的多导睡眠图（PSG）评估同时记录。为每个研究对象手动提取3个无噪声呼吸周期的声音，并将其隔离为吸气和呼气阶段段。在15毫秒的窗口中计算每个呼吸阶段声音信号的功率谱，相邻窗口之间有50%的重叠。然后将UAR估计为100至2500赫兹内每个窗口的功率谱能量与其相应气流的比值。然后，计算每个呼吸阶段短时间窗口UAR的方差，即Var（UAR）。发现三个OSA组之间吸气和呼气之间对数尺度的Var（UAR）比值有显著差异（p<0.01）；还发现它与AHI高度相关。这些结果与OSA人群中上呼吸道通畅性不保持恒定的假设一致，并表明清醒时声学UAR的变化可能被视为OSA的预测指标。
