Early Cystic Fibrosis Detected Using Bronchoalveolar Lavage And Lung Clearance Index

According to a new Australian study published online before he print publication in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine, the lung clearance index (LCI) is a sensitive, non-invasive marker of early lung disease in young children with cystic fibrosis (CF).

Yvonne Belessis, MBBS, MPH, PhD, respiratory staff specialist at Sydney Children's Hospital declared:

"We found that LCI is elevated early in children with CF, especially in the presence of airway inflammation and Pseudomonas aeruginosa. LCI may not only be a marker of early CF lung disease, but may be useful as an objective outcome measure in future studies of young children with CF."

The researchers identified LCI following a multiple breath washout (MBW) conducted in 47 presymptomatic/minimally symptomatic infants and infants with CF with an average age of 1.55 years, and in 25 healthy controls aged on average 1.26 years. They also performed Bronchoalveolar lavage (BAL) in those suffering from cystic fibrosis.

The upper limit for a normal LCI was defined as 7.41. The findings revealed an average (SD) LCI in cystic fibrosis children with CF of 7.21 (0.81), as compared to 6.45 (0.49) in control children (P<.001). 15 (32%) from 47 CF children showed an elevated LCI. The researchers were able to repeat and reproduce all LCI measurements.

The findings also revealed that 17 (36%) children with CF, including 7 (15%) children with Pseudomonas aeruginosa infection suffered from an infection of the airway (≥105 cfu/mL BAL fluid). The results showed that LCI in children with Pseudomonas was 7.92 (1.16) and 7.02 (0.56) in those without this infection (P=.038). The researchers detected a substantial association between LCI and BAL inflammatory markers interleukin-8 and neutrophil count.

The researchers acknowledge the limitations of their study, which include the lack of a robust measure of structural lung disease and a higher diagnostic threshold for airway infection than used in other BAL studies.

Dr. Belessis concludes:

"We obtained reproducible measurements of LCI at the bedside of sedated infants and young children using a portable MBW system. Compared with healthy controls, LCI was elevated in well infants and young children with CF, and abnormal LCI was associated with Pseudomonas aeruginosa infection and airway inflammation. Our results show that the LCI is a feasible, sensitive and repeatable non-invasive marker of early lung disease in well infants and young children with CF. Longitudinal assessment of the LCI taking into consideration changes in inflammation and airway infection over time are needed to confirm these findings."