Can Scondand Sacinbe estimated from two multiple breath washout tests across childhood?

Abstract

Background: Multiple breath washout (MBW) offers high feasibility but is time consuming. Lung Clearance Index (LCI) can be accurately derived from the 1st two acceptable tests across the entire paediatric age range. Applicability for concentration normalised phase III slope (Sn III ) parameters S cond and S acin remains unclear outside of adolescence. Aims and Objectives: To compare LCI, FRC, S cond and S acin derived from 1st two vs. all three acceptable tests in preschool, early school age and adolescent children. Methods: Retrospective analysis of 80 children (33 CF) to date with clinical MBW tests at a tertiary paediatric centre (commercial nitrogen based MBW equipment, Ecomedics Exhalyser D, Switzerland). S III defined from 65-95% of expired volume. Results derived from the 1st two vs. all three acceptable tests compared using paired t-test and Bland-Altman analysis. Results: In adolescent and early school age children no significant difference was observed for any MBW parameter estimates. In preschool children, S acin was significantly higher from two tests (p=0.01) with wide 95% limits of agreement (95%LA,-0.102 – 0.170). Data shown as mean (SD). *p value Conclusion: Accurate MBW estimates of FRC, LCI, Scond and Sacin can be obtained from two tests in school aged children. SnIII analysis in preschool children over 1st two runs results in higher Sacin values, compared to all three tests.