Abstract
The direction of the initial deflection of the wave-form (DID) of coarse crackles from fifteen patients and fine crackles from ten patients was studied. In coarse crackles, 93.4±4.0% of DID was upward on inspiration and 93.2±10.9% was downward on expiration. In fine crackles, DID was upward in 95.4±3.2%. An experiment simulating coarse crackles proved that their DID should be determined by sudden changes in intrabronchial pressure following the rupture of bubbles in the airways.
In fine crackles, DID is thought to go upward by the compression wave propagated around the fibrous distal airways which suddenly extend in the late phase of inspiration. These characteristic DID distribution patterns in coarse and fine crackles may be a useful clue for classification of rales, and, furthermore, DID analysis will provide us with a new means to study generating mechanisms of discontinuous adventitious lung sounds.
