View source for Crackles

{{short description|Respiratory sounds associated with abnormal lung conditions}}
{{For|other meanings|Crackle (disambiguation){{!}}Crackle}}
{{Infobox medical condition
| name            = Crackles
| synonyms        = Crepitations, rales
| image           = Crackles pneumoniaO.ogg  
| caption         = Crackles heard in the lungs of a person with pneumonia using a stethoscope.
| pronounce       = {{IPAc-en|audio=En-us-Rales.ogg|ˈ|r|ɑː|l|z}} {{respell|RAHLZ|'}} or {{IPAc-en|ˈ|r|æ|l|z}} {{respell|RALZ|'}}<ref>{{Citation |last = Jones |first = Daniel | name-list-style = vanc |author-link = Daniel Jones (phonetician) |title = English Pronouncing Dictionary | editor-first = Peter | editor-last1 = Roach | editor-first2 = James | editor-last2 = Hartmann | editor-first3 = Jane | editor-last3 = Setter |place = Cambridge |publisher = Cambridge University Press |orig-year = 1917 |year = 2003 |isbn=978-3-12-539683-8 }}</ref>
| field           = [[Pulmonology]]
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'''Crackles''' are the [[clicking noise|clicking]], rattling, or [[crackling noise]]s that may be made by one or both [[lung]]s of a [[human]] or [[animal]]<ref>Domínguez-Ruiz M, Reinero CR, Vientos-Plotts A, Grobman ME, Silverstein D, Gomes E, Le Boedec, K Association between respiratory clinical signs and respiratory localization in dogs and cats with abnormal breathing patterns. In The Veterinary Journal, Volume 277, November 2021</ref> with a [[respiratory disease]] during [[inhalation]], and occasionally during exhalation. They are usually heard only with a [[stethoscope]] ("on [[auscultation]]"). Pulmonary crackles are abnormal breath sounds that were formerly referred to as '''rales'''.<ref>Cahalin LP, Buck LA. Physical Therapy Associated With Cardiovascular Pump Dysfunction and Failure. In: DeTurk WE, Cahalin LP. eds. ''''Cardiovascular and Pulmonary Physical Therapy: An Evidence-Based Approach, 3e''''. McGraw-Hill;  Accessed August 16, 2020</ref>

''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 called ''bilateral 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 and [[Pulmonary alveolus|alveoli]] collapsed by fluid, [[exudate]], or lack of aeration during expiration.

Crackles can be heard in people or animals who have [[pneumonia]], [[atelectasis]], [[pulmonary fibrosis]], acute [[bronchitis]], [[bronchiectasis]], [[acute respiratory distress syndrome]] (ARDS), [[interstitial lung disease]] or post [[thoracotomy]] or [[metastasis]] [[ablation]]. [[Pulmonary edema]] secondary to left-sided [[congestive heart failure]] and [[High-altitude pulmonary edema|high altitude pulmonary edema]] can also cause crackles.

==Terminology==
[[René Laennec]] adopted the existing word ''[[wikt:râle#French|râles]]'' (which has been translated as "rattles", "groans" and otherwise) to describe the added [[respiratory sounds|breath sound]]s 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 of ''le râle de la mort'', which translates to "the [[death 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 word ''[[wikt:rhonchus#Latin|rhonchus]]'', 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's ''De L'Auscultation Mediate''.<ref name="Laennec_1819">{{cite book | vauthors = Laennec RT | date = 1819 | url = https://books.google.com/books?id=TtTTeKls2bUC&pg=PR5 | title = De l'Auscultation Médiate, ou Traité du Diagnostic des Maladies des Poumons et du Coeur | location = Paris | publisher = Brosson & Chaudé | trans-title = On Mediate Auscultation or Treatise on the Diagnosis of the Diseases of the Lungs and Heart | language = French }}</ref><ref name="Laennec_Forbes_translation">{{cite book | vauthors = Laennec RT |translator-last = Forbes | translator-first = John | url = https://books.google.com/books?id=a1pBAQAAIAAJ&pg=PR1 | title = A Treatise on the Diseases of the Chest and on Mediate Auscultation | date = 1835 | location = New York & Philadelphia | publisher = Samuel Wood & Sons; Desilver, Thomas & Co. }}</ref> The difficulty of translating ''râle'' itself had been remarked upon in a British review of Laennec's work in 1820.<ref name="Foreign_Medicine_and_Surgery_1820">{{Citation |year=1820 |title=Laennec's new system of diagnosis |journal=The Quarterly Journal of Foreign Medicine and Surgery and of the Sciences Connected with Them |volume=2 |pages=51–68 |url=https://books.google.com/books?id=LNVLAAAAYAAJ&q=%22difficulty+in+translating%22&pg=PA51 }}</ref>

The terminology of ''rales'' and ''rhonchi'' in English remained variable until 1977, when a standardization was established by the [[American Thoracic Society]] and [[American College of Chest Physicians]].<ref name="ReferenceA">{{cite journal|title=Report of the ATS-ACCP Ad Hoc Subcommittee on pulmonary nomenclature|journal=ATS News|year=1977|volume=3|pages=5–6}}</ref> As a result, the term ''râles'' was abandoned, and ''crackles'' became its recommended substitute.<ref name="ReferenceA"/><ref name="Forgacs1978">{{cite journal | vauthors = Forgacs P | title = The functional basis of pulmonary sounds | journal = Chest | volume = 73 | issue = 3 | pages = 399–405 | date = March 1978 | pmid = 630938 | doi = 10.1378/chest.73.3.399 }}</ref> The term ''rales'' is still common in English-language medical literature<!--as an easy search for the term at PubMed Central confirms, e.g., https://www.ncbi.nlm.nih.gov/pmc/?term=%22rales%22-->, but cognizance of the ATS/CHEST guidelines calls for ''crackles''.

==Sound==
Crackles are caused by explosive opening of small airways<ref name="Forgacs1978"/> and are discontinuous,<ref>{{cite web | url = https://medical-dictionary.thefreedictionary.com/rale | title = Rale | work = [[TheFreeDictionary.com]] }}</ref> 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.

* 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 [[interstitial pulmonary fibrosis|pulmonary fibrosis]] or [[congestive heart failure]]. The sounds from interstitial pulmonary fibrosis have been described as sounding like opening a [[Velcro]] fastener.
** Coarse crackles are somewhat louder, lower in pitch, and last longer than fine crackles. Their presence usually indicates an airway disease, such as [[bronchiectasis]].

They can also be described as unilateral or bilateral,<ref>{{cite web | url = http://www.rightdiagnosis.com/sym/unilateral_crackles.htm | work = Rightdiagnosis.com | title = Unilateral crackles }}</ref> as well as dry or moist/wet.<ref>{{cite book|last1=Paz|first1=Jaime C.|last2=West|first2=Michele P. | name-list-style = vanc | chapter = Chapter 2; Respiratory System |title=Acute care handbook for physical therapists | date = 2009 | publisher = Saunders/Elsevier | location = St. Louis, Mo. | isbn = 978-1-4160-6948-5 | page = 56 | edition = 3rd | chapter-url = https://books.google.com/books?id=QeMDAQAAQBAJ&q=dry+wet+crackles&pg=PA56 }}</ref>

== Associated diagnoses ==
Crackles are often associated with inflammation or infection of the small bronchi, bronchioles, and alveoli.

Crackles that do not clear after a cough may indicate [[pulmonary edema]] or fluid in the alveoli due to [[heart failure]], [[pulmonary fibrosis]], or [[acute respiratory distress syndrome]]. Crackles that partially clear or change after coughing may indicate [[bronchiectasis]].

== Interobserver consistency ==
In 2016, the [[European Respiratory Society]] reported on a study of various physicians listening to audiovisual recordings of auscultation findings and [[inter-rater reliability|interobserver variation]] was analyzed.<ref name="pmid_27158515">{{cite journal |vauthors=Melbye H, Garcia-Marcos L, Brand P, Everard M, Priftis K, Pasterkamp H |year=2016 |title=Wheezes, crackles and rhonchi: simplifying description of lung sounds increases the agreement on their classification: a study of 12 physicians' classification of lung sounds from video recordings |journal=BMJ Open Respiratory Research |volume=3 |issue=1 |pages=e000136 |doi=10.1136/bmjresp-2016-000136 |pmc=4854017 |pmid=27158515}}</ref> The study found that broad descriptions agreed better than detailed descriptions.<ref name="pmid_27158515" />

== See also ==
* [[Bronchophony]]
* [[Egophony]]
* [[Tuberculosis|Consumption]]
* [[Whooping cough]]
* [[Croup]]
* [[Pertussis toxin]]
* [[Allergic asthma]]
* [[Respiratory sounds]]

== References ==
{{Reflist}}

== External links ==
{{Medical resources
|   ICD10       = {{ICD10|R|09|8|r|00}} 
|   ICD9        = {{ICD9|786.7}} 
}}
* [http://respwiki.com/Breath_sounds Audio Breath Sounds] {{Webarchive|url=https://web.archive.org/web/20201215121532/http://respwiki.com/Breath_sounds |date=2020-12-15 }} - Multiple case studies with audio files of lung sounds.
* [http://www.rale.ca/Recordings.htm R.A.L.E. Repository] - sound files of breath sounds

{{Circulatory and respiratory system symptoms and signs}}

[[Category:Symptoms and signs: Respiratory system]]