Comparison of difference in LCI (LCI_N2−LCI_SF6) to FEV₁ (% predicted).

Healthy controls are represented by the open circles and subjects with CF by the solid circles. The difference in LCI was greater as FEV₁ became lower such that on average LCI_N2 was disproportionately higher than LCI_SF6 in subjects with abnormal spirometric findings.