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.