Effect of posture on lung clearance index (LCI) and lung volumes in children with early stage cystic fibrosis lung disease

Abstract

Introduction: LCI is a sensitive marker of ventilation heterogeneity (VH) in early CF lung disease. Posture may affect VH, yet LCI is often compared to imaging techniques of VH performed whilst supine. To enable a fair comparison, the effect of posture on LCI needs to be understood. Aim: To explore the effects of posture on VH in health and CF Method: 16 children with mild CF (FEV 1 >LLN) and 9 age matched healthy control subjects were recruited as part of a larger study. Each child performed multiple breath washout (MBW) using a modified Innocor and spirometry. Triplicate MBW measurements were performed when seated upright and then repeated supine and the mean value recorded. Results: No significant differences between CF and control groups for age, height, FEV 1 , and seated LCI were observed (Table 1). In both groups, there was a significant fall in FRC on lying supine (p Conclusion: There is a significant fall in FRC when lying supine in CF and controls. In CF children with minimal disease supine posture increases overall VH as measured by LCI. This has implications for interpretation of imaging comparisons with MBW. Supine testing may further enhance sensitivity of MBW.