Change in crackle characteristics among male adult smokers

Abstract

Smoking is the main cause of Chronic Obstructive Pulmonary Disease (COPD) with the highest incidence of diagnosed COPD in males with age of 40 years and upwards. Crackle characteristics have been reported to indicate and differentiate COPD and other cardiopulmonary diseases. However, no studies have investigated the change of crackle characteristics among smokers within this specific group. The aim of this study was to compare crackle characteristics between adult male smokers and non smokers. Twenty smokers (10 mild (pack year: 9.05±3.9) and 10 moderate (pack year: 32.95±4.2)); age 8.95±6.4 year) and 20 non-smokers (age 50.90±5.3 year) with normal spirometry test were recruited into the study. Lung sound data were recorded, without airflow control, using a digital stethoscope (ThinkLabs ds32a, USA) connected to a laptop computer. The results showed significantly higher number of crackles per breathing cycle (NCpB) in smokers in all six areas across chest wall when compared with non smokers (p=0.043 for anterior left, p=0.009 for anterior right, p=0.032 for lateral left, p=0.008 for lateral right, p=0.015 for posterior left and p=0.001 for posterior right). These initial results indicate that NCpB might be able to reflect changes of the lung among adult smokers with normal spirometry test. This suggests that NCpB could possibly be used as an early indicator of smoking damage before turning to COPD, though a larger sample is needed to confirm it.