Novel approach to continuous adventitious respiratory sound analysis for the assessment of bronchodilator response

PLoS One. 2017 Feb 8;12(2):e0171455. doi: 10.1371/journal.pone.0171455. eCollection 2017.

Abstract

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.

MeSH terms

  • Adult
  • Aged
  • Algorithms
  • Asthma / diagnosis
  • Asthma / drug therapy
  • Asthma / physiopathology
  • Bronchodilator Agents / pharmacology
  • Bronchodilator Agents / therapeutic use*
  • Female
  • Forced Expiratory Volume / drug effects
  • Humans
  • Male
  • Middle Aged
  • Models, Theoretical
  • Reproducibility of Results
  • Respiratory Sounds / diagnosis*
  • Respiratory Sounds / drug effects*
  • Spirometry
  • Treatment Outcome

Substances

  • Bronchodilator Agents

Grants and funding

This work was supported by Secretary of Universities and Research of the Department of Economy and Knowledge of the Government of Catalonia (http://universitatsirecerca.gencat.cat/ca/inici/) (Consolidated research group GRC 2014 SGR 1569), RJ; CERCA Programme / Generalitat de Catalunya (http://cerca.cat/en/), RJ; The Spanish Ministry of Economy and Competitiveness (http://www.mineco.gob.es/portal/site/mineco/menuitem.19368ee62a6eae4c2adf03a0026041a0/?vgnextoid=f2e9154527515310VgnVCM1000001d04140aRCRD&lang_choosen=en) and the European Regional Development Fund (http://ec.europa.eu/regional_policy/en/funding/erdf/) (DPI2015-68820-R), RJ. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.