Quantifying crackles in the lung of smoking and non-smoking young adults

Abstract

Crackle sounds are associated with a variety of lung disorders. Smoking is also associated with many of the changes in the lung and airways leading to crackles. However, studying crackles as an indication of pathologic changes related to cigarette smoking in the lung is an underdeveloped area of research which needs to be explored. This study was undertaken to investigate whether differences in the crackles' characteristics (duration of two cycle deflection (2CD) and number of crackles per breathing cycle (NCBC)) in the lung of smoking and non-smoking young adults could be found and to quantify these differences, if present, using a digital stethoscope and computer aided lung sound analysis (CALSA). Sixty male subjects (30 smokers and 30 non-smokers) with an average age of 26.6 years (SD ± 4.7) were recruited, drawn from students at the University of Southampton in the United Kingdom. The lung sound data were recorded on one occasion using a digital stethoscope connected to a laptop running MATLAB to record and store the lung sounds from seven anatomical sites on the chest. The 2CD and NCBC per site in 25 second recordings were calculated using data from each of the anatomical sites used for recording lung sounds (excluding the trachea). No statistically significant differences in NCBC per site were found between smokers and non-smokers at any anatomical location. The 2CD per site data revealed some statistically significant differences at both anterior sites (anterior left: F (2, 57) = 9.40, P = 0.00; anterior right: F (2, 57) = 9.51, P = 0.00)) and both lateral sites (middle left: F (2, 57) = 4.2, P = 0.02; middle right: F (2, 57) = 4.36, P = 0.02)). The hypothesis that lung crackle’s 2CD differ between smokers and non-smokers has been supported but the hypothesis that NCBC differ between smokers and non-smokers has not been supported.

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Identifiers

ORCID for Anne Bruton: orcid.org/0000-0002-4550-2536

ORCID for Anna Barney: orcid.org/0000-0002-6034-1478

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