Department of Power Engineering, North China Electric Power University, Baoding, 071003, China.
School of Mechanical and Vehicle Engineering, Beijing Institute of Technology, Beijing, 100081, China.
Biomech Model Mechanobiol. 2024 Feb;23(1):227-239. doi: 10.1007/s10237-023-01769-4. Epub 2023 Oct 13.
The frequency characteristics of lung sounds have great significance for noninvasive diagnosis of respiratory diseases. The rales in the lower respiratory tract region that can provide rich information about symptoms of respiratory diseases are not clear. In this paper, a three-dimensional idealized bifurcated lower respiratory tract geometric model, which contains 3 to 13 generation (G-G) bronchi is constructed, where , and then the large eddy simulation and volume of fluid are used to study the fluid flow characteristics. Ffowcs Williams and Hawkings model are subsequently used to study the frequency characteristics of rale of different generations of bronchi. The results showed that bronchial blockage and sputum movement will enhance the turbulence intensity and vortex shedding intensity of flow. The dominant frequency and highest value of sound pressure level (SPL) of rhonchi/moist crackles decrease with the increase of bronchial generation. The change rates of dominant frequency of rhonchi / moist crackles in adjacent generations were 5.0 ± 0.1 ~ 9.1 ± 0.2% and 3.1 ± 0.1 ~ 11.9 ± 0.3%, respectively, which is concentrated in 290 ~ 420 Hz and 200 ~ 300 Hz, respectively. The change rates of SPL of rhonchi/moist crackles were 8.8 ± 0.1 ~ 15.7 ± 0.1% and 7.1 ± 0.1 ~ 19.5 ± 0.2%, respectively, which is concentrated in 28 ~ 50 dB and 16 ~ 32 dB, respectively. In the same generation of bronchus (e.g., G, G) with the same degree of initial blockage, the dominant frequency and SPL of moist crackles can be 3.7 ± 0.2% and 4.5 ± 0.3% slightly higher than that of rhonchi, respectively. This research is conducive to the establishment of a rapid and accurate noninvasive diagnosis system for respiratory diseases.
肺部声音的频率特征对非侵入性诊断呼吸疾病具有重要意义。在呼吸道区域产生的罗音，可以提供有关呼吸疾病症状的丰富信息，但目前还不清楚。在本文中，构建了一个包含 3 到 13 代（G-G）支气管的三维理想分支下呼吸道几何模型，然后使用大涡模拟和体积流来研究流体流动特性。随后使用 Ffowcs Williams 和 Hawkings 模型来研究不同代支气管罗音的频率特征。结果表明，支气管阻塞和痰液运动将增强流动的湍流强度和涡旋脱落强度。罗音/湿啰音的主频和最高声压级（SPL）随着支气管代次的增加而降低。相邻代罗音/湿啰音主频的变化率分别为 5.0±0.1%至 9.1±0.2%和 3.1±0.1%至 11.9±0.3%，集中在 290420Hz 和 200300Hz。罗音/湿啰音的 SPL 变化率分别为 8.8±0.1%至 15.7±0.1%和 7.1±0.1%至 19.5±0.2%，分别集中在 2850dB 和 1632dB。在相同代次的支气管（例如 G、G）中，具有相同初始阻塞程度的情况下，湿啰音的主频和 SPL 可以分别比罗音高 3.7±0.2%和 4.5±0.3%。这项研究有助于建立快速准确的呼吸疾病非侵入性诊断系统。
