Feasibility of lung clearance index in a clinical setting in pre-school children

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 (LCI ) 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 LCI would increase success rates.116 pre-school children (28 healthy controls and 88 with respiratory disease), median age 4.0 years (range 2-6 years), underwent MBW tests unsedated in a clinic setting, using sulfur hexafluoride as a tracer gas and an adapted photoacoustic gas analyser.81 (70%) out of 116 children completed LCI and 72% completed LCI measurement. Test success increased significantly in patients over 3 years (0% at 3 years, p3 years old, and LCI is raised in those with respiratory disease. Use of LCI did not increase success rate in pre-schoolers.