| Crackles | |
|---|---|
| Other names | Crepitations, rales |
| Crackles heard in the lungs of a person with pneumonia using a stethoscope. | |
| Pronunciation | |
| Specialty | Pulmonology |
Crackles are theclicking, rattling, orcrackling noises that may be made by one or bothlungs of ahuman oranimal[2] with arespiratory disease duringinhalation, and occasionally during exhalation. They are usually heard only with astethoscope ("onauscultation"). Pulmonary crackles are abnormal breath sounds that were formerly referred to asrales.[3]
Bilateral crackles refers to the presence of crackles in both lungs. Basal crackles are crackles apparently originating in or near the base of the lung.Bibasal crackles, also calledbilateral basal crackles, are crackles heard at the bases of both the left and right lungs.
Crackles are caused by the "popping open" of small airways andalveoli collapsed by fluid,exudate, or lack of aeration during expiration.
Crackles can be heard in people or animals who havepneumonia,atelectasis,pulmonary fibrosis, acutebronchitis,bronchiectasis,acute respiratory distress syndrome (ARDS),interstitial lung disease or postthoracotomy ormetastasisablation.Pulmonary edema secondary to left-sidedcongestive heart failure andhigh altitude pulmonary edema can also cause crackles.
René Laennec adopted the existing wordrâles (which has been translated as "rattles", "groans" and otherwise) to describe the addedbreath sounds that are now referred to as "crackles". He described them using unusual daily examples, such as "whistling of little birds", "crackling of salt on a heated dish", "cooing of the woodpidgeon", etc., but he soon realized that he was unable to use the term in front of his patients because it conjured the association ofle râle de la mort, which translates to "thedeath rattle", the noise that people who are about to die make when they can no longer clear secretions. Therefore, at the bedside, he used the Latin wordrhonchus, which originally meant a "snore". That was not clearly understood by his translator, John Forbes, and the terminology became very confusing after the publication in the 1830s of Forbes's English translation of Laennec'sDe L'Auscultation Mediate.[4][5] The difficulty of translatingrâle itself had been remarked upon in a British review of Laennec's work in 1820.[6]
The terminology ofrales andrhonchi in English remained variable until 1977, when a standardization was established by theAmerican Thoracic Society andAmerican College of Chest Physicians.[7] As a result, the termrâles was abandoned, andcrackles became its recommended substitute.[7][8] The termrales is still common in English-language medical literature, but cognizance of the ATS/CHEST guidelines calls forcrackles.
Crackles are caused by explosive opening of small airways[8] and are discontinuous,[9] nonmusical, and brief. Crackles are more common during the inspiratory than the expiratory phase of breathing, but they may be heard during the expiratory phase.
They can also be described as unilateral or bilateral,[10] as well as dry or moist/wet.[11]
Crackles are often associated with inflammation or infection of the small bronchi, bronchioles, and alveoli.
Crackles that do not clear after a cough may indicatepulmonary edema or fluid in the alveoli due toheart failure,pulmonary fibrosis, oracute respiratory distress syndrome. Crackles that partially clear or change after coughing may indicatebronchiectasis.
In 2016, theEuropean Respiratory Society reported on a study of various physicians listening to audiovisual recordings of auscultation findings andinterobserver variation was analyzed.[12] The study found that broad descriptions agreed better than detailed descriptions.[12]