Act when you hear inspiratory crackles

Identification of symptoms of suspected fibrotic interstitial lung diseases (ILDs), most tellingly ‘Velcro-like’ crackles on auscultation, should trigger prompt referral1–5



Identification of symptoms of suspected fibrotic interstitial lung diseases (ILDs), most tellingly ‘Velcro-like’ crackles on auscultation, should trigger prompt referral activities1–5

Suspect fibrotic ILD early in your patients who experience a combination of:6–8


Bilateral fine crackles (‘fine crackles’ are discontinuous, high-pitched, low amplitude, short duration crackles9) on chest auscultation that have a distinctive ‘Velcro-like’ character and are heard during middle to late inspiration.10 They tend to be heard almost exclusively over the dependent (+/-basal) lung regions and are changed very little by coughing.10 The sounds may be gradually or suddenly extinguished by having the patient bend forward, thus removing the effect of gravity.11

Not all breathlessness is COPD, asthma or CHF.12,13 Suspect pulmonary fibrosis


The presence of ‘Velcro-like’ crackles on lung auscultation is valuable in identifying fibrotic ILD early, as it has an excellent sensitivity and good specificity for pulmonary fibrosis3,14

  • ‘Velcro-like’ crackles on lung auscultation predicts the presence of fibrotic ILD according to a study in patients undergoing chest HRCT scans for various clinical indications14
  • ‘Velcro-like’ crackles of fibrotic ILDs on lung auscultation are distinct from coarse crackles of other lung conditions, such as chronic bronchitis and severe pulmonary edema9,15 and predicts the presence of pulmonary fibrosis14

In lung auscultation, flow-volume loops are helpful in the detection of large airway abnormalities, such as pulmonary fibrosis:16–18

  • A small and concave or scooped curve suggests obstructive disorders, such as chronic obstructive pulmonary disease (COPD) and asthma
  • A small curve with a steep slope suggests restrictive disorders, such as ILDs and chest wall deformities

Differentiate restrictive disease – hear the difference in lung auscultation and compare flow-volume loops between obstructive disease, healthy lungs and restrictive disease18,19


Reprinted with permission from: Al-Ashkar F, Mehra R, Mazzone P. Interpreting pulmonary function tests: Recognize the pattern, and the diagnosis will follow. Cleve Clin J Med 2003; 70(10) 866-881. Copyright © 2023 Cleveland Clinic Foundation. All rights reserved.

*The obstructive auscultation audio file used represents COPD. The x-axis of flow-volume loops may also increase from the origin; although the position of all loops may start at the origin, the shape of the loop can be used to recognize lung disorders.16,17,22–24

Use the interactive slideshow of lung auscultation sounds and flow-volume loops to help differentiate restrictive disease.


Suspect ILD in patients with:1,2,14,16–18,21,22,25


‘Velcro-like’ crackles on lung auscultation, and/or


Flow-volume loops indicating restrictive disease

And rapidly refer to a lung specialist1,2


ILDs usually have a restrictive pattern in spirometry16

  • Normal forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) with low FVC, or FEV1/FVC >70% where FVC is reduced more than FEV1, is seen in restrictive lung disease, such as ILDs and chest wall deformities17,18
  • Low FEV1/FVC, or FEV1/FVC <70% where FEV1 is reduced more than FVC, signifies obstructive lung disease, such as COPD and asthma17,18

Despite ILDs being often characterized by restrictive patterns on PFTs, patients can have other pathologies that could result in mixed or sometimes pure obstructive patterns on PFTs26–31


  • Regularly assess for non-specific pulmonary symptoms for early identification of ILD33–35
  • Perform lung auscultation as ‘Velcro-like’ crackles are the most telling sign of fibrotic ILD3,4


The key to early and accurate diagnosis of fibrotic ILDs is high-resolution computed tomography (HRCT) combined with multidisciplinary evaluation36,37

  • HRCT allows for the recognition of abnormalities which may not be apparent on chest X-ray38

Chest X-ray can detect pulmonary abnormalities39 and complications, such as pleural effusion and infection;40 however, chest X-ray alone is ultimately inaccurate for ILD detection39

While chest X-ray alone is not sensitive enough for ILD diagnosis, it can play a role in identification ILDs38

  • An abnormal chest X-ray is often the first indication of ILD – even prior to the development of symptoms or physiologic impairment41

Chest X-ray may be used in routine screening for lung cancer, or other conditions, to observe the presence or absence of lung abnormalities. This presents another potential opportunity to pursue identification of suspected ILD through referral to an ILD specialist


Reprinted from Annals of the American Thoracic Society, 205, Raghu G, Remy-Jardin M, Richeldi L et al, Idiopathic Pulmonary Fibrosis (an update) and progressive pulmonary fibrosis in adults. An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline. e18–e47, ©2023.


CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; CT, computed tomography; Echo, echocardiogram; EKG, electrocardiogram; HRCT, high-resolution computed tomography; ILD, interstitial lung disease; PFT, pulmonary function test; SOB, shortness of breath.

Initial symptoms of ILDs can be nonspecific1,2 – help your patient avoid misdiagnosis by treating ‘Velcro-like’ crackles as a distinguishing trigger for prompt referral1,3


COPD, chronic obstructive pulmonary disease; CTD, connective tissue disease; CHF, congestive heart failure; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; HRCT, high-resolution computed tomography; ILD, interstitial lung disease; PFT, pulmonary function test.

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