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Use of zonal distribution of lung crackles during inspiration and expiration to assess disease severity in idiopathic pulmonary fibrosis
  1. Angela L Key1,2,
  2. Kimberley Holt1,2,
  3. Christopher J Warburton1,
  4. Paul Phillip Walker1,
  5. John E Earis1,2
  1. 1Department of Respiratory Medicine, University Hospital Aintree, Liverpool, UK
  2. 2Department of Health Sciences, University of Salford, Salford, UK
  1. Correspondence to Dr Paul Phillip Walker, Department of Respiratory Medicine, University Hospital Aintree, Liverpool L9 7AL, UK; ppwalker{at}


Purpose of the study To measure the number and distribution of crackles in patients with idiopathic pulmonary fibrosis (IPF) and assess how this relates to measures of disease severity.

Study design Fourteen patients with IPF had both the number of crackles per litre of lung volume and lung function measured every 3 months for 1 year. Crackle counts were expressed according to position (upper and lower zones) and whether they occurred during inspiration and expiration.

Results At baseline, crackle count per unit volume was higher at the bases than the apices and higher during inspiration than during expiration. There was a significant relationship between lung function and number of crackles per unit volume. Upper zone crackles during inspiration (crackle count vs forced vital capacity (FVC): r=0.69, p=0.007) and lower zone crackles during expiration (crackle count vs FVC: r=0.55, p=0.04) demonstrated the strongest relationship with lung function.

Conclusions Number and distribution of crackles in IPF relate to physiological measures of disease severity. Inspiratory lower zone crackles were universal and extensive but the presence, hence, development of inspiratory upper zone crackles and expiratory lower zone crackles correlated with measures of poorer lung function. The presence or appearance of these assessed using chest auscultation provides a clinician with simple measure of disease severity, and possibly progression, prompting further physiological assessment and review of treatment.

  • adult thoracic medicine
  • interstitial lung disease
  • respiratory physiology

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  • Contributors ALK, CJW and JEE were involved in study concept and design. ALK, KH and JEE were involved in data acquisition. All authors were involved in data analysis or interpretation. ALK, PPW and JEE were involved in manuscript drafting. All authors were involved in critical manuscript revision and have provided final manuscript approval.

  • Funding This work was funded by the British Lung Foundation (Grant No TCO4/3).

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval St Helens and Knowsley Local Research and Ethics Committee (No 05/Q1508/43)

  • Provenance and peer review Not commissioned; externally peer reviewed.