RT Journal Article
SR Electronic
T1 Spectral and waveform characteristics of fine and coarse crackles.
JF Thorax
JO Thorax
FD BMJ Publishing Group Ltd and British Thoracic Society
SP 651
OP 657
DO 10.1136/thx.46.9.651
VO 46
IS 9
A1 M Munakata
A1 H Ukita
A1 I Doi
A1 Y Ohtsuka
A1 Y Masaki
A1 Y Homma
A1 Y Kawakami
YR 1991
UL http://thorax.bmj.com/content/46/9/651.abstract
AB Two acoustically different types of lung crackles, fine and coarse, occur in different pathophysiological conditions. To differentiate these crackles from objective characteristics of frequency information, crackles were recorded from 16 patients with pulmonary fibrosis judged clinically to have "fine" crackles and from 10 with chronic bronchitis who had mainly "coarse" crackles. Time expanded waveforms (1/4 cycle duration, initial deflection width, two cycle duration, and 9/4 cycle duration; duration of the first 1/4, 2/4, 8/4, and 9/4 cycles of crackle waveforms) were examined and fast Fourier transform analysis (peak and maximum frequencies) was performed. All waveform measurements for fine crackles were significantly smaller than those for coarse crackles. Peak and maximum frequencies for fine crackles were significantly higher than those for coarse crackles. Although there was some overlap in these values for individual crackles between the two groups when average values of these measurements were calculated for each patient, there was no overlap between fine and coarse crackles and the two groups could be clearly separated. Log peak frequency and log maximum frequency correlated better with 9/4 cycle duration (r = 0.85, 0.84) and two cycle duration (r = 0.87, 0.86) than with 1/4 cycle duration (r = 0.66, 0.77) or initial deflection width (r = 0.67, 0.79). Early and late segments of crackles have different characteristics, probably related to the origin of the sound and the resonance of the lung respectively. These results suggest that spectral and waveform characteristics may help to improve the accuracy of pulmonary auscultation and increase knowledge of how crackles are generated.