Ploysongsang Y, Iyer V K, Ramamoorthy P A
Department of Internal Medicine, University of Cincinnati College of Medicine, Ohio.
Respiration. 1990;57(5):313-7. doi: 10.1159/000195863.
Unfiltered breath sounds (NF) from the apical area of the heart, lung volume and ECG signals were recorded in 5 normal subjects. The signals were digitized and subjected to three methods of heart sound cancellation: 75-Hz high-pass filtering (75 HF), ECG-triggered blanking (BL) and adaptive filtering (AF). The sound signals were then subjected to the fast Fourier transform algorithm to obtain power spectra. Inspiratory and expiratory phase sounds of five breaths of each subject were analyzed separately. The inspiratory and expiratory sound power spectra were very similar and skewed slightly to the right, and therefore characterized by median frequencies. The differences between inspiratory and expiratory median frequencies were insignificant for NF: 42.90 +/- 2.03 (mean +/- SD) vs. 46.64 +/- 2.53 Hz (p greater than 0.1); for 75 HF: 106.43 +/- 10.27 vs. 118.22 +/- 6.30 Hz (p greater than 0.5); for BL: 44.46 +/- 3.33 vs. 66.73 +/- 2.93 Hz (p greater than 0.1), for AF: 49.72 +/- 5.68 vs. 79.20 +/- 13.07 Hz (p greater than 0.1). We conclude that the lack of significant differences suggests similar mechanisms and sites of production of inspiratory and expiratory vesicular breath sounds.
在5名正常受试者中记录了来自心尖区的未滤波呼吸音（NF）、肺容量和心电图信号。这些信号被数字化，并采用三种心音消除方法：75赫兹高通滤波（75 HF）、心电图触发消隐（BL）和自适应滤波（AF）。然后对声音信号进行快速傅里叶变换算法以获得功率谱。分别分析了每个受试者五次呼吸的吸气相和呼气相声音。吸气和呼气声音功率谱非常相似，且略向右偏斜，因此以中位数频率为特征。对于NF，吸气和呼气中位数频率之间的差异不显著：42.90±2.03（平均值±标准差）对46.64±2.53赫兹（p>0.1）；对于75 HF：106.43±10.27对118.22±6.30赫兹（p>0.5）；对于BL：44.46±3.33对66.73±2.93赫兹（p>0.1），对于AF：49.72±5.68对79.20±13.07赫兹（p>0.1）。我们得出结论，缺乏显著差异表明吸气和呼气肺泡呼吸音的产生机制和部位相似。
