Early detection of lung disease in firefighters: A sound frequency analysis

Abstract

Early detection of lung disease in vulnerable groups is key to prevention of impairment. Spirometry may be inadequate in achieving this goal. Spirometry inadequately reflects regional variation in lung injury. We looked at using an electronic stethoscope with sound frequency analysis to detect early lung damage in firefighters. The purpose of this study was to investigate the utility of breath sound frequency analysis in detecting early lung damage. We sought to determine the significance of asymmetry of lung injury. Recordings of breath sounds using an electronic stethoscope of the left and right lung was performed on 11 asymptomatic firefighters with a normal spirometry and 10 normal controls. Frequency analysis was performed and analyzed for their frequency peaks and their energy content. The average number of high energy peaks above 150 Hz was significantly lower in normals at 0.70 compared to firefighters at 1.82 p value of 0.03. Firefighters had higher maximum frequencies in the right lung compared to normals 184.5 Hz vs 162.3 Hz that was statistically significant p=0.036 but not for left lung. There was a significant increase in variability of maximum frequencies between lungs in firefighters compared to normal p value at .00026. An electronic stethoscope may be useful in detecting early lung damage in vulnerable populations in individuals with normal spirometry. It may be important to establish standards that reflect regional heterogeneity as a marker of early lung damage. This may not be reflected in measurements of global lung function such as spirometry. Further investigation into the heterogeneity of breath sounds and its relationship to particle deposition due to bronchial asymmetry is needed.