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The multiple breath washout technique is a lung function test that tells us how evenly gas mixes in the lung. In diseased lungs, regions of the lungs can be either partially or completely closed resulting in less gas mixing in these regions and uneven gas mixing in the lung. The lung clearance index is a measure of how evenly gas mixes in the lung, with higher values indicating uneven mixing and worse lung function. 

We assessed whether the lung clearance index would be higher in preschool children with cystic fibrosis compared with healthy children. We also assessed whether the lung clearance index would be higher in children with cystic fibrosis who had detectable inflammation and infection in the lungs compared to those without.

We performed the multiple breath washout test in 82 visits with 58 children with cystic fibrosis and 38 visits with 31 healthy children aged three to six years. Children with cystic fibrosis also underwent bronchoalveolar lavage collection for detection of lower respiratory tract inflammation and infection.

The lung clearance index was higher in children with cystic fibrosis compared with healthy controls. In children with cystic fibrosis, the lung clearance index was higher in those with lower respiratory tract infections and inflammation detected in the lung.

Our data indicates that the lung clearance index is sensitive to the presence and extent of inflammation and respiratory pathogens in bronchoalveolar lavage fluid in preschool children with cystic fibrosis. The lung clearance index may be an important tool for monitoring clinical status and response to therapeutic interventions in preschool children with cystic fibrosis. 

 

Authors: Kathryn A. Ramsey, Rachel E. Foong, Jasmine Grdosic, Alana Harper, Billy Skoric, Charles Clem, Miriam Davis, Lidija Turkovic, Stephen M. Stick1, Stephanie D. Davis, Sarath C. Ranganathan, and Graham L. Hall on behalf of AREST CF.

Published in Annals of the American Thoracic Society, September 2017