Image: Flow chart of the proposed respiratory sound recording and CAS analysis approach.
The study proposes new signal processing algorithms to detect and characterize CAS, such as wheezes, which may be different between asthmatics with and without a significant bronchodilator response (BDR). The new technique evaluates CAS with results that go beyond those currently provided by spirometry, which is the usual way of assessing BDR in such patients.
When a sufferer’s airway obstruction has been confirmed by spirometry, a BDR test is usually performed to measure the variation in airflow limitation, high variability being one of the main components of an asthma diagnosis. While a thorough analysis of CAS can provide distinct and complementary information about BDR, the current standard BDR criterion is a subject of controversy, mainly due to low sensitivity.
Asthma patients who came to the Pulmonology Service at the Hospital Germans Trias i Pujol, Badalona, for regular examinations from 2011 to 2015 were recruited for the BDR test and to participate in the respiratory sound recording and analysis study.
Using the new technique, the researchers found appreciable changes in CAS features of asthma patients, revealing alterations in airway obstruction that were not detected by spirometry, and allowing the BDR findings to be sorted into three consistent categories.
The new technique is a highly sensitive and non-invasive tool that contributes to improving the stratification of BDR levels, as well as offering a direct clinical application for assessing and managing of patients with obstructive pulmonary diseases.
Lozano-García M, Fiz JA, Martínez-Rivera C, Torrents A, Ruiz-Manzano J, Jané R (2017). Novel approach to continuous adventitious respiratory sound analysis for the assessment of bronchodilator response. PLoS ONE