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Abnormal lung sounds in patients with asthma during episodes with normal lung function
H J Schreur1, J Vanderschoot, A H Zwinderman
1Department of Pulmonology, University Hospital of Leiden, The Netherlands.
Chest
|July 1, 1994
Summary
Even with normal lung function, asthma patients exhibit distinct lung sound characteristics. Lung sound intensity is lower and pitch higher in asthmatics, suggesting airway inflammation affects sound generation and transmission.
Area of Science:
- Respiratory Medicine
- Pulmonology
- Biomedical Engineering
Background:
- Clinically stable asthma patients with normal lung function show airway inflammation and mucosal swelling.
- Subtle airway changes in asthma may alter lung sound characteristics.
Purpose of the Study:
- To investigate if lung sound analysis can differentiate symptom-free mild asthma patients from healthy individuals.
- To explore the relationship between airway inflammation and lung sound properties in stable asthma.
Main Methods:
- Simultaneous recording of airflow, lung volume, and lung sounds during quiet and forced breathing in 9 asthma patients and 8 healthy controls.
- Computation of flow-dependent power spectra using fast Fourier transform.
- Analysis of lung sound intensity (LSI), frequency parameters (Q25%-Q75%), and wheezing (W, W%) using ANOVA.
Main Results:
- Lower lung sound intensity (LSI) during expiration in asthma patients, especially at low airflow.
- Higher frequency parameters (Q25%-Q75%) during quiet expiration in asthmatics.
- No significant difference in wheezing (W, W%) between groups.
Conclusions:
- Lung sounds in symptom-free stable asthma patients are lower in intensity and higher in pitch compared to healthy controls, even with normal lung function.
- Airflow-standardized phonopneumography may serve as a non-invasive method to detect airway morphologic changes in asthma.