Spirometry and plethysmography parameters expressed as per cent of predicted and z scores
| Functional parameters | % of predicted | z Scores | ||
| Range | Mean (SD) | Range | Mean (SD) | |
| FEV1 | 31.0–136.0 | 85.3 (24.6) | −2.82 – 1.47 | −0.60 (1.0) |
| FVC | 47.0–138.0 | 93.4 (18.5) | −2.86 – 2.05 | −0.35 (1.0) |
| FEF25/75 | 10.0–151.0 | 63.2 (34.4) | −2.63 – 1.49 | −1.07 (1.0) |
| FEV1/FVC | 42.0–98.8 | 75.45 (13.35) | −2.86 – 1.08 | −0.67 (1.0) |
| Raw | 55.4–310.6 | 164.5 (62.9) | −0.71 – 3.35 | 1.02 (1.0) |
| sRaw | 71.0–739.2 | 269.0 (142.0) | −0.20 – 4.50 | 1.19 (1.0) |
| sReff | 64.0–680.7 | 240.6 (128.1) | −0.28 – 4.53 | 1.09 (1.0) |
| FRC | 101.2–248.0 | 159.3 (31.2) | −0.04 – 4.74 | 1.90 (1.0) |
| RV | 83.0–397.0 | 196.5 (69.4) | −0.24 – 4.28 | 1.39 (1.0) |
| TLC | 85.0–174.0 | 119.2 (16.7) | −0.89 – 4.46 | 1.15 (1.0) |
| RV/TLC | 91.0–305.0 | 161.0 (45.6) | −0.20 – 4.49 | 1.34 (1.0) |
FEV1, forced expiratory volume in 1 s; FRC, functional residual capacity; FVC, forced vital capacity; Raw, airway resistance; RV, residual volume; sRaw, specific airway resistance; sReff, effective specific resistance; TLC, total lung capacity.