Spirometry and multiple breath inert gas washout (MBW) measurements
| Parameter | Mean (SD) z-scores |
| FEV1 (n=27)* | −1.59 (1.44) |
| FVC (n=27)* | −0.71 (1.36) |
| FEF25–75 (n=27)* | −2.11 (1.39) |
| FEV1/FVC ratio (n=27)* | −1.40 (1.08) |
| LCI (n=27)† | 7.58 (5.57) |
| Scond (n=23)† | 9.64 (4.08) |
| Sacin (n=23)† | 5.99 (4.60) |
| FRCSF6, ml (n=27) | 1649 (603) |
↵* Spirometry parameters calculated using the British growth reference charts.
↵† MBW z-scores calculated using Swedish normative data.
FEV1, forced expiratory volume in 1 s; FRC, functional residual capacity; FVC, forced vital capacity; FEF25–75, forced expiratory flow at 25–75% of FVC; LCI, lung clearance index; Scond and Sacin, normalised phase III slope indices (see text for explanation).