Respiratory sounds : Advances beyond the stethoscope

Objective: This paper describes state of the art, scientific publications and ongoing research related to the methods of analysis of respiratory sounds.

Methods and material: Review of the current medical and technological literature using Pubmed and personal experience.

Results: The study includes a description of the various techniques that are being used to collect auscultation sounds, a physical description of known pathologic sounds for which automatic detection tools were developed. Modern tools are based on artificial intelligence and on technics such as artificial neural networks, fuzzy systems, and genetic algorithms…

Conclusion: The next step will consist in finding new markers so as to increase the efficiency of decision aid algorithms and tools.

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Analysis of Respiratory Sounds: State of the Art

Wheeze detection based on time-frequency analysis of breath sounds

Computerized lung sound analysis is a multidiscipli-nary ﬁeld. Work in this ﬁeld would be easier if the terms tobe used were clearly deﬁned. This chapter is meant fordoctors, engineers and other persons who are workingwith respiratory sound analysis.The terms collected in this paper of the ComputerizedRespiratory Sound Analysis (CORSA) guidelines includeterms of respiratory diseases, pulmonary physiology,acoustics, automatic data handling and instrumentation.The list includes terms that have not yet been deﬁnedclearly in the literature, or deﬁned in a controversial way.Some terms included have been deﬁned elsewhere, e.g .the terms of lung function variables, but were regardeduseful to be included in this selection in order to improvethe readability. Some general terms have also beenincluded in cases where the common sense meaning ofthat term is different from the speciﬁc meaning in the dis-cipline of respiratory sound research.Each deﬁnition of a term includes, as a rule, a short for-mal deﬁnition, some additional characteristics and refer-ences if available. Ofﬁcial guidelines (European Respir atorySociety Guidelines for Lung Function Studies, AmericanThoracic Society publications) position papers, statementsand reports of international societies as well as originalpapers and review articles in scientiﬁc international jour-nals have been used as references. Handbooks have alsobeen used.The terms deﬁned are listed in alphabetical order, andhave been used systematically in the CORSA guidelines.For the deﬁnition of different kinds of sounds, anattempt has been made to make clear distinctions betweenadjectives indicating locations (like lung, trachea, etc.),

Definition of terms for applications of respiratory sounds

In the clinic, the wheezing sound is usually considered as an indicator symptom to reflect the degree of airway obstruction. The auscultation approach is the most common way to diagnose wheezing sounds, but it subjectively depends on the experience of the physician. Several previous studies attempted to extract the features of breathing sounds to detect wheezing sounds automatically. However, there is still a lack of suitable monitoring systems for real-time wheeze detection in daily life. In this study, a wearable and wireless breathing sound monitoring system for real-time wheeze detection was proposed. Moreover, a breathing sounds analysis algorithm was designed to continuously extract and analyze the features of breathing sounds to provide the objectively quantitative information of breathing sounds to professional physicians. Here, normalized spectral integration (NSI) was also designed and applied in wheeze detection. The proposed algorithm required only short-term data of breathing sounds and lower computational complexity to perform real-time wheeze detection, and is suitable to be implemented in a commercial portable device, which contains relatively low computing power and memory. From the experimental results, the proposed system could provide good performance on wheeze detection exactly and might be a useful assisting tool for analysis of breathing sounds in clinical diagnosis.

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Design of Wearable Breathing Sound Monitoring System for Real-Time Wheeze Detection.

Breath sounds were recorded in normal and asthmatic children over the chest and trachea. The power spectra of the sounds were analyzed for peaks of high amplitude and high frequency as indications of wheezing. The percent of inspiration and expiration spent wheezing was used as an indication of the severity of bronchial obstruction. Wheezing was found to be strongly dependent upon air flow, and generally followed the changes in pulmonary function as indicated by the forced expiratory volume at 1 s (FEV1). The trachea was found to be a better location for analyzing wheezes than the lung.

T. Richard Fenton

Papers

Automated Spectral Characterization of Wheezing in Asthmatic Children