Lung crackle characteristics in patients with asbestosis, asbestos-related pleural disease and left ventricular failure using a time-expanded waveform analysis--a comparative study.

The aim of this study is to investigate lung crackle characteristics by time-expanded waveform (TEW) analysis in patients with asbestosis (AS), asbestos-related pleural disease (ARPD) and left ventricular failure (LVF). TEW was performed on a 33 s recording from each of 40 patients (12 AS, 17 ARPD and 11 LVF). They were 38 men and two women. Crackles on TEW were counted during inspiration and expiration, and the timing of clusters of crackles with respect to inspiration and expiration was noted. A total of 1117 crackles were identified. The initial deflection width (IDW) and the two cycle duration (2CD) were calculated for all crackles within one respiratory cycle for each patient (total of 298 crackles). Crackles were detected by TEW in all patients with AS, in seven patients with ARPD and in nine patients with LVF. Crackles in AS were mainly fine, mid- to late-inspiratory. Crackles in LVF took three patterns; in the first there were repetitive mid- to late inspiratory crackles similar to those seen in AS except that the crackles in LVF tended to be medium and coarse as well as fine (three patients); in the second crackles started early in inspiration followed by a crackle-free period then by another cluster of crackles lasting to the end of inspiration and to the early third of expiration (four patients) and in the third there were repetitive expiratory crackles with no or few inspiratory crackles (two patients). Crackles in ARPD generally took the configuration of fine crackles but another type of crackle preceded by a sharp deflection followed by an M-shape oscillation then by the largest oscillation was also found. IDW and 2CD for inspiratory crackles in ARPD were shorter than those in AS and LVF (for IDW P < 0.009 and P < 0.003 compared with AS and LVF respectively and for 2CD, P < 0.006 and P < 0.003 compared with AS and LVF respectively). IDW and 2CD in AS tended to be shorter than these for LVF but these results did not reach statistical significance. It is concluded that many differences exist between crackles in AS, LVF and ARPD. Differences in nature and timing of crackles may reflect differences in the pathophysiology and mechanism giving rise to lung crackles in these conditions. TEW provides informations of diagnostic value.