Novel approach to continuous adventitious respiratory sound analysis for the assessment of bronchodilator response.
BACKGROUND
A thorough analysis of continuous adventitious sounds (CAS) can provide distinct and complementary information about bronchodilator response (BDR), beyond that provided by spirometry. Nevertheless, previous approaches to CAS analysis were limited by certain methodology issues. The aim of this study is to propose a new integrated approach to CAS analysis that contributes to improving the assessment of BDR in clinical practice for asthma patients.


METHODS
Respiratory sounds and flow were recorded in 25 subjects, including 7 asthma patients with positive BDR (BDR+), assessed by spirometry, 13 asthma patients with negative BDR (BDR-), and 5 controls. A total of 5149 acoustic components were characterized using the Hilbert spectrum, and used to train and validate a support vector machine classifier, which distinguished acoustic components corresponding to CAS from those corresponding to other sounds. Once the method was validated, BDR was assessed in all participants by CAS analysis, and compared to BDR assessed by spirometry.


RESULTS
BDR+ patients had a homogenous high change in the number of CAS after bronchodilation, which agreed with the positive BDR by spirometry, indicating high reversibility of airway obstruction. Nevertheless, we also found an appreciable change in the number of CAS in many BDR- patients, revealing alterations in airway obstruction that were not detected by spirometry. We propose a categorization for the change in the number of CAS, which allowed us to stratify BDR- patients into three consistent groups. From the 13 BDR- patients, 6 had a high response, similar to BDR+ patients, 4 had a noteworthy medium response, and 1 had a low response.


CONCLUSIONS
In this study, a new non-invasive and integrated approach to CAS analysis is proposed as a high-sensitive tool for assessing BDR in terms of acoustic parameters which, together with spirometry parameters, contribute to improving the stratification of BDR levels in patients with obstructive pulmonary diseases.
Biomedical Signal Processing and Interpretation Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain.|Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.
Manuel
http://orcid.org/0000-0002-4146-9839
M
Lozano-García
Biomedical Signal Processing and Interpretation Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain.|Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.|Pulmonology Service, Germans Trias i Pujol University Hospital, Badalona, Spain.
José Antonio
JA
Fiz
Pulmonology Service, Germans Trias i Pujol University Hospital, Badalona, Spain.
Carlos
C
Martínez-Rivera
Pulmonology Service, Germans Trias i Pujol University Hospital, Badalona, Spain.
Aurora
A
Torrents
Pulmonology Service, Germans Trias i Pujol University Hospital, Badalona, Spain.
Juan
J
Ruiz-Manzano
Biomedical Signal Processing and Interpretation Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain.|Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.|Department of Automatic Control (ESAII), Universitat Politècnica de Catalunya (UPC)-Barcelona Tech, Barcelona, Spain.
Raimon
R
Jané
D000328:Adult; D000368:Aged; D000465:Algorithms; D001249:Asthma / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology; D001993:Bronchodilator Agents / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D015203:Reproducibility of Results; D012135:Respiratory Sounds / Q000175:diagnosis* / Q000187:drug effects*; D013147:Spirometry; D016896:Treatment Outcome
D001993:Bronchodilator Agents