Research findings published in BMJ Open Respiratory Research suggest fine crackles on chest auscultation are sensitive enough to establish an early diagnosis of idiopathic pulmonary fibrosis (IPF).

The study’s researchers prospectively evaluated the presence and type of crackles on chest auscultation in 290 patients (mean age, 70.1 years; 58% male) who were referred to a Canadian interstitial lung disease (ILD) clinic. For each patient, clinicians recorded the presence of fine crackles, coarse crackles, or both independently.

According to the researchers, fine crackles are defined as “nonmusical discontinuous sounds best heard on mid-to-late inspiration, unaffected by cough.” Compared with coarse crackles, fine crackles are shorter in duration as well as higher in pitch, the researchers explained. They added that coarse crackles feature a “popping” quality sound that can sometimes resolve upon coughing.


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At presentation, fine crackles on auscultation were reported in approximately 93% of patients with IPF and 73% of patients with non-IPF ILD. Fine crackles in the IPF population (n=129) were more common than cough (86%), dyspnea (80%), low diffusing capacity (87%), low total lung capacity (57%), and low forced vital capacity (50%).

The investigators reported a 90% observer agreement in identifying fine crackles at and a 40% agreement in identifying course crackles at the subsequent clinic visit, with an overall agreement rate of 84%. A multiple regression analysis found that lung function, symptoms, emphysema, chronic obstructive pulmonary disease, obesity, or clinician experience did not affect the identification of fine crackles (P >.05).

A limitation of the study was the lack of primary care physicians involved, which the researchers indicate could limit the generalizability of the results across these care providers.

The investigators concluded that their findings that support the sensitivity of fine crackles for early identification of IPF are “particularly important given the current availability of antifibrotic drugs that can slow down the progression of IPF and other progressing fibrotic lung diseases.”

Disclosure: Multiple authors declared affiliations with the pharmaceutical industry. Please refer to the original article for a full list of disclosures.

Reference

Moran-Mendoza O, Ritchie T, Aldhaheri S. Fine crackles on chest auscultation in the early diagnosis of idiopathic pulmonary fibrosis: a prospective cohort study. BMJ Open Respir Res. 2021;8(1):e000815. doi:10.1136/bmjresp-2020-000815