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Crackles:
Crackles are discontinuous, brief sounds heard more commonly on inspiration.
They can be classified as
- fine (high pitched, very brief) or
- coarse (low pitched, less brief).
Crackles can be produced by two common mechanisms.
- When previously closed small airways suddenly open. To see how this can happen, gently close your wet lips and open them suddenly. You will hear a 'plop'. When this happens in the terminal bronchioles, fine crackels are produced.
- Another explanation is that air bubbles through secretions as in pulmonary edema and resolving pneumonia.
Causes:
- bronchiectasis
- pulmonary edema
- ARDS
- consolidation
- fibrosis
- asthma
- chronic bronchitis
- interstitial lung disease
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