The feasibility of lung clearance index (LCI) in a clinical setting in pre-school children

Abstract

Introduction: Lung function testing in pre-school children in the clinical setting is challenging. Most cannot perform spirometry and many infant lung function tests require sedation. Lung clearance index (LCI) derived from the multiple breath washout (MBW) test has been shown to be sensitive to early disease changes but may be time consuming and so a shortened test (LCI0.5) may be more feasible in young children. We sought to establish feasibility of MBW in unsedated pre-school children in a clinic setting, and hypothesised use of LCI0.5 would increase success rates. Methods: 116 pre-school children (28 healthy controls, 88 respiratory disease), median age 4.0 (range 2-6) years performed MBW test unsedated in a clinic setting, using sulphur hexafluoride (SF6) as a tracer gas and an adapted photoacoustic gas analyser. Results: 81/116 (70%) completed LCI and 72% completed LCI0.5. Test success increased significantly in patients over 3 years (0% <2.5yrs, 33% 2.5-3yrs, 70%>3yrs, p<0.0001). LCI was elevated in those with respiratory disease compared with healthy controls. Conclusions: MBW is feasible in a clinic setting in unsedated pre-schoolers, particularly in those over 3 years old, and LCI is raised in those with respiratory disease. Use of LCI0.5 did not increase success rate in pre-schoolers.