دانلود رایگان مقاله تغییرات در صدای ریه درطول پیشرفت بیماری آسم

abstract

Background: Lung sound analysis is useful for objectively evaluating airways even in children with asymptomatic asthma. However, the relationship between lung sounds and morphological changes in the airways has not been elucidated. We examined the relationship between lung sounds and chronic morphological changes in the airways during the progression of asthma from onset in guinea pigs. Methods: Eleven male guinea pigs were examined; of these, seven were used as asthma models and four as controls. The asthma models were sensitized and repeatedly challenged by inhaling albumin chicken egg. We measured lung sounds and lung function twice a week for 21 weeks. After the final antigen challenge, the lungs were excised for histological examination. We measured the ratio of airway wall thickness to the total airway area and the ratio of the internal area to the total airway area in the trachea, third bronchi, and terminal bronchioles. Results: Among the lungs sounds, the difference between the two groups was greatest with respect to inspiratory sound intensity. The ratio of airway wall thickness to the total airway area of the terminal bronchioles was greater in the asthma models than in the controls, and it correlated best with the changes in inspiratory sound intensity in the 501e1000-Hz range (r ¼ 0.76, p < 0.003). Conclusions: Lung sound intensity in the middle frequency range from 501 to 1000 Hz correlated with peripheral airway wall thickness. Inspiratory sound intensity appeared to be an indicator of morphological changes in small airways in asthma.

Discussion

In the present study, the lung sound intensity in the middle frequency ranged from 501 to 1500 Hz, particularly from 501 to 1000 Hz, in the inspiratory phase, indicating a morphological change in the small airways in a chronic asthma model. The change in the lung sounds during the disease process from the onset of asthma appeared to reflect thickening of the bronchial wall and narrowing of the lumen of the peripheral airways. We reported that our index, named ic700, which is an index of lung sound intensity, could detect airway dysfunction in children with asymptomatic asthma while avoiding the influences of airflow and body size.14 The ic700 is the sound intensity at 700 Hz in the inspiratory phase that can be an indicator of chronic structural changes in asthmatic airways in asymptomatic subjects without wheezes. Many studies on the changes in breath sounds in asthmatic conditions have focused on the changes in breath sound generation and/or transmission.13 However, there have been no reports on the change in lung sounds and its correlation with bronchial structural change directly. In the present study, we attempted to clarify the relationship between the changes in inspiratory sounds and morphological changes in the airways in asthma. Normal inspiratory sounds are generated primarily within the lobar and segmental airways, whereas expiratory sound are generated from more proximal locations.26,27 Our results are consistent with these previous findings.