Lung clearance index could reduce reliance on CT

Cystic fibrosis

By Tony James

16 Sep 2015

The lung clearance index can identify the extent of structural lung disease in children with cystic fibrosis and may prove helpful in reducing the reliance on CT imaging, Perth researchers have found.

Professor Graham Hall, from the Telethon Kids Institute in Perth, and colleagues said the index, derived without radiation exposure using multiple breath washout, had been suggested as a surrogate for CT in patents with cystic fibrosis but the associations with early structural changes had been unclear.

Writing in the American Journal of Respiratory and Critical Care Medicine, they concluded that the index could be a useful surveillance tool in children but could not replace CT to screen for bronchiectasis.

The study found it was insensitive to structural disease in infants aged 0 to 2, correlated with total disease extent in pre-schoolers aged 3 to 6, and correlated with extent of total disease, bronchiectasis and air trapping in children aged 7 to 16.

“It’s clear that infants and young children with CF can exhibit structural lung disease such as bronchiectasis even when clinically well,” Professor Hall told the limbic.

“The use of chest CT, incorporating low dose protocols, and bronchoalveolar lavage offer clinicians opportunities to identify the early onset of lung disease and to tailor management protocols accordingly.

“Measurement of lung clearance index may offer insight into the progression of early lung disease, but evidence for its role in managing individual patients is still needed.

“It’s hoped that in the future LCI can complement the range of tools available to health professionals and maximise health outcomes in these patients.”

Structural lung abnormalities are known to develop early in patients with cystic fibrosis and they progress rapidly into irreversible structural disease, Professor Hall and his colleagues said in their report.

Interventions should ideally commence early in life to delay the onset and progression of structural changes but effective, personalised interventions need accurate and simple techniques to monitor disease severity.

“There is a clear imperative for the development of minimally invasive and sensitive markers of structural lung disease that can be applied routinely in the clinical setting,” they said.

CT is the gold standard but, despite advances in technology allowing lower doses, the exposure to radiation restricts the frequency of imaging.

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