| ICD-10 | R09.8 |
|---|---|
| ICD-9 | 786.7 |
Rales, crackles or crepitations, are the clicking, rattling, or crackling noises heard on auscultation of (listening to) the lung with a stethoscope during inhalation.
Crackles are caused by the "popping open" of small airways and alveoli collapsed by fluid, exudate, or lack of aeration during expiration. The word "rales" derives from the French word râle meaning "rattle".
Crackles can be heard in patients with pneumonia, atelectasis, pulmonary fibrosis, acute bronchitis, or bronchiectasis. Pulmonary edema secondary to left-sided congestive heart failure can also cause rales.
The terms rales and crepitations are both still in common use in the US but less common elsewhere.[1] Use of the term rales has been discouraged by the American Thoracic Society and American College of Chest Physicians since 1977,[2] by numerous authors since,[3] and this is enforced by the editorial policy of a number of major medical journals.[1]
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The sound of crackles
Crackles are caused by explosive opening of small airways,[3] are discontinuous, [4] nonmusical and brief. Crackles are much more common during the inspiratory than the expiratory phase of breathing, but they may be heard during the expiratory phase. Crackles are often associated with inflammation or infection of the small bronchi, bronchioles, and alveoli. Crackles that don't clear after a cough may indicate pulmonary edema or fluid in the alveoli due to heart failure or Acute respiratory distress syndrome.
- Crackles are often described as fine, medium, and coarse. They can also be characterized as to their timing: fine crackles are usually late-inspiratory, whereas coarse crackles are early inspiratory.
- Fine crackles are soft, high-pitched, and very brief. This sound can be simulated by rolling a strand of hair between one's fingers near the ears, or by moistening one's thumb and index finger and separating them near the ears. Their presence usually indicates an interstitial process, such as pulmonary fibrosis or congestive heart failure.
- Coarse crackles are somewhat louder, lower in pitch, and last longer than fine crackles. They have been described as sounding like opening a Velcro fastener. Their presence usually indicates an airway disease, such as bronchiectasis.
Crackles can be heard over the lower lobe of the lungs. Pulmonary edema makes it more audible.
See also
References
- ^ a b RL Wilkins, JR Dexter and JR Smith (1984). "Survey of adventitious lung sound terminology in case reports". Chest 85: 523–525. doi:. http://chestjournal.org/cgi/content/abstract/85/4/523.
- ^ "Report of the ATS-ACCP Ad Hoc Subcommittee on pulmonary nomenclature". ATS News 3: 5–6. 1977.
- ^ a b Forgacs P (1978). "The functional basis of pulmonary sounds" (PDF). Chest 73 (3): 399–405. doi:. PMID 630938. http://www.chestjournal.org/cgi/reprint/73/3/399.
- ^ rale at Dorland's Medical Dictionary
External links
- MedEd at Loyola medicine/pulmonar/images/earlyral.au Audio file of rales
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