Crackles (rales) in the interstitial pulmonary diseases

Our plain-English summary of Crackles (rales) in the interstitial pulmonary diseases, by G.R. Epler, C.B. Carrington, E.A. Gaensler (Chest, 1978).

The study

• Authors: G.R. Epler, C.B. Carrington, E.A. Gaensler
• Journal: Chest
• Published: 1978;73(3):333-9
• Cited by: 70 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 002120).

Abstract

There is renewed interest in the classification and methods of recording adventitious pulmonary sounds. This is a study of the importance of fine crackles (rales) in the diagnosis and estimation of the severity of diffuse infiltrative pulmonary disease. Among 272 cases documented by lung biopsy, bilateral fine crackles were heard in 60 percent of those with interstitial pneumonias and asbestosis but in only 20 percent of those with sarcoidosis and other granulomatoses. These incidences were identical in 335 patients diagnosed clinically. In 322 selected ambulatory patients with chronic obstructive pulmonary disease, fine crackles were recorded in only 10 to 12 percent, while coarse crackles were not uncommon in patients with chronic bronchitis. In workers exposed to asbestos, crackles correlated with exposure. In serial studies of such workers, the occurrence of crackles alone appeared to be a random event, while among those with crackles together with one other of five criteria, almost one-half developed asbestosis within four to six years. Fine crackles correlated with pathologic severity, with radiographic honeycombing, and with physiologic abnormalities.

In plain English

The authors studied whether fine crackles (rales: crackling sounds heard through a stethoscope) help in diagnosing diffuse lung disease and judging its severity, using clinical data they had coded on referred patients for 26 years. Among 272 patients diagnosed by lung biopsy, bilateral fine crackles were heard in 60 percent of those with usual interstitial pneumonia and of those with asbestosis, while crackles were relatively uncommon in granulomatous diseases such as sarcoidosis. In asbestosis and sarcoidosis, rates of fine crackles in 335 clinically diagnosed patients did not differ significantly from those in biopsy-diagnosed patients. In 322 ambulatory patients with chronic obstructive lung disease, fine crackles were recorded in 10 to 12 percent. Among asbestos-exposed worker groups, the share with crackles ranged from 31 percent among shipyard pipe coverers to 3 percent among briefly exposed filter-paper workers; a separate group of normal subjects also had 3 percent. Among 294 workers followed four to six years, none of nine whose only finding was crackles developed "asbestosis" (three or more of six criteria), but nearly half of those with crackles plus one other criterion did. The authors concluded that fine crackles are characteristic of the chronic interstitial pneumonias.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective analysis of clinical, physiologic, radiographic and pathologic data coded over 26 years on referred patients, plus industrial surveys of asbestos-exposed workers, some followed serially for four to six years
• Who was studied: Three groups: (1) 272 patients with chronic infiltrative lung diseases diagnosed by lung biopsy, plus 335 patients with asbestosis or sarcoidosis diagnosed clinically; (2) 322 selected ambulatory patients with chronic obstructive pulmonary disease (chronic bronchitis or 'emphysema'); (3) 662 asbestos-exposed workers, of whom 294 were followed for at least four to six years. Comparison groups included 34 patients with biopsy-confirmed asbestosis, 73 shipfitters used as controls and 59 normal persons. Patients were referred to the Thoracic Services at Boston University School of Medicine; dates are not given.
• Exposure: Asbestos dust at various levels (fiber type not specified). Jobs: manufacturing of fire-proofing products, shipyard pipe coverers with significant exposure, shipfitters without significant exposure, laggers in submarine construction, and filter-paper workers from two plants (one using asbestos for 25 years, the other for less than seven years)
• Main results:
  • Among the 272 biopsy-diagnosed patients, bilateral fine crackles were heard in 60 percent of patients with usual interstitial pneumonia and in 60 percent of those with interstitial pneumonia attributed to asbestos exposure (asbestosis).
  • In the granulomatous diseases (sarcoidosis, eosinophilic granuloma, allergic alveolitis, miliary tuberculosis), all types of crackles were relatively uncommon.
  • In asbestosis and sarcoidosis, the rate of fine crackles in biopsy-diagnosed patients and in the 335 clinically diagnosed patients did not differ significantly. In sarcoidosis, the rates were 18 percent and 14 percent respectively.
  • In the 322 selected ambulatory patients with chronic obstructive pulmonary disease, fine crackles were recorded in only 10 to 12 percent.
  • In usual interstitial pneumonia, fine crackles correlated significantly with histologic severity graded from lung biopsy. On a 0 to 5 scale, the mean was 4.1 in patients with fine crackles and 2.8 in those with no crackles (P less than 0.01). Radiographic honeycombing was present in 22 of 37 patients (59 percent) with fine crackles and in 3 of 12 (25 percent) with no crackles.
  • In sarcoidosis, the severity and distribution of bronchiolar granulomas did not correlate with crackles.
  • Sputum production tended to be more common in patients with crackles, but this trend was significant only in usual interstitial pneumonia.
  • Among 662 asbestos-exposed workers, 69 (10 percent) had "asbestosis" as the authors defined it (three or more of six criteria).
  • Among the groups of exposed workers, the percentage with crackles ranged from 31 percent in the pipe coverers to 3 percent in the briefly exposed filter-paper workers. The separate comparison group of normal subjects also had 3 percent. In pipe coverers, counting crackles as a criterion raised the percentage with "asbestosis" from 22 percent to 29 percent.
  • In all groups, crackles were the only abnormality in 3 percent or less of persons.
  • In 34 patients with biopsy-confirmed asbestosis, the number of criteria for "asbestosis" correlated well with the histologic severity of disease.
  • Of 294 exposed workers followed four to six years, nine had bilateral fine crackles as the only criterion at first examination. None developed "asbestosis", and in most of them the crackles were not heard at later examinations. The authors judged crackles alone to be a random event. Of the 13 workers with fine crackles plus one other criterion, nearly one-half later developed "asbestosis".
  • Among patients with various biopsy-confirmed interstitial diseases, crackles correlated significantly with decreasing diffusing capacity (Dsb) and decreasing FVC, but not with FEV1/FVC. In COPD, crackles were heard almost exclusively in patients with severe obstruction.
• The authors' conclusion: The authors concluded that fine crackles are characteristic of the chronic interstitial pneumonias. In their experience, the finding is most useful in patients with unexplained shortness of breath, where fine crackles together with abnormal gas exchange may indicate interstitial disease even when the chest x-ray is normal. They stated that their asbestos-worker survey data support using rales as one of several clinical criteria for diagnosing interstitial disease.
• Limitations the authors state:
  • The variance in the comparisons of crackles with histologic, radiographic and physiologic severity was large, perhaps because the crackles were not measured. The authors stated that severity therefore could not be predicted by their auscultation.

Topics

Medical terms in this study, explained in our Lexicon: Interstitial, Biopsy, Bilateral, Honeycombing.

Related studies

• Lung crackle characteristics in patients with asbestosis, asbestos-related pleural disease and left ventricular failure using a time-expanded waveform analysis--a comparative study — N. al Jarad, S.W. Davies, et al. (1994)
• Exercise alveolar-arterial oxygen pressure difference in interstitial lung disease — C. Risk, G.R. Epler, et al. (1984)
• Multinuclear giant cells in bronchoalveolar lavage in interstitial lung diseases — C. Agustí, A. Xaubet, et al. (1987)
• Relative release of interleukin-1 beta and interleukin-1 receptor antagonist by alveolar macrophages. A study in asbestos-induced lung disease, sarcoidosis, and idiopathic pulmonary fibrosis — J.N. Kline, D.A. Schwartz, et al. (1993)
• Interstitial pulmonary fibrosis environmental or idiopathic? — G.L. Snider (1985)
• Chitotriosidase activity in sarcoidosis and some other pulmonary diseases — M. Tercelj, B. Salobir, et al. (2009)

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