Lung Sound Analysis and the Respiratory Cycle Dependence of Impulse Oscillometry in Asthma Patients

Objective A lung sound analysis (LSA) is useful for detecting airway inflammation and obstruction in patients with asthma. To elucidate the mechanism of LSA, we investigated the relationship between the exhalation-to-inhalation sound pressure ratio in the low frequency range between 100 and 195 Hz (...

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Bibliographic Details
Published in:	Internal Medicine 2019/01/01, Vol.58(1), pp.47-52
Main Authors:	Shimoda, Terufumi, Obase, Yasushi, Nagasaka, Yukio, Kishikawa, Reiko, Iwanaga, Tomoaki
Format:	Article
Language:	eng
Subjects:	Adult Aged Asthma Asthma - drug therapy Asthma - physiopathology bronchial asthma Corticoids Corticosteroids Dependence Exhalation Exhalation - physiology Female Frequency ranges Humans impulse oscillometry Inhalation Inhalation - physiology lung sound analysis Lungs Male Middle Aged Multivariate analysis Original Oscillometry Pressure ratio Reactance Resonant frequencies Respiration respiratory cycle dependence respiratory function Respiratory Function Tests Respiratory Sounds Respiratory system Respiratory tract Respiratory tract diseases Sound pressure Wheezing Young Adult
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Summary:	Objective A lung sound analysis (LSA) is useful for detecting airway inflammation and obstruction in patients with asthma. To elucidate the mechanism of LSA, we investigated the relationship between the exhalation-to-inhalation sound pressure ratio in the low frequency range between 100 and 195 Hz (E/I LF) and the respiratory cycle dependence of impulse oscillometry (IOS) parameters. Methods Asthma patients underwent IOS [resistance of the respiratory system at 5 Hz (R5) and 20 Hz (R20), the reactance area (AX), resonant frequency of reactance (Fres), and reactance of the respiratory system at 5 Hz (X5) ], spirography, and an LSA. The correlation between the LSA-derived E/I LF values and the respiratory cycle dependence of the IOS parameters was analyzed. Patients Thirty-four patients with mild to moderate bronchial asthma, who had not received oral or inhaled corticosteroids and who had no episodes of rumbling or wheezing were examined. Results The E/I LF value was significantly correlated with the differences of the R5 and R5-R20 values between exhalation and inhalation (p=0.035 and p=0.050) in a multivariate analysis. Conclusion E/I LF appears to be an index that expresses the respiratory cycle dependence of asthma as well as IOS.
ISSN:	0918-2918 1349-7235