Resting PFT in an upright sitting and supine position
| Upright sitting position | Supine position | ||||||
| Measured | LLN | ULN | Reference (mean value) | % of reference | Measured | % of reference | |
| VC L | 4.13 | 4.33 | 6.17 | 5.25 | 79% | 2.70 | 51% |
| TLC L | 5.79 | 6.07 | 8.37 | 7.22 | 80% | 4.17 | 58% |
| FRC L | 2.39 | 2.43 | 4.41 | 3.42 | 70% | 1.65 | 48% |
| IC L | 3.40 | 3.47 | 98% | 2.52 | 73% | ||
| RV L | 1.65 | 1.24 | 2.58 | 1.91 | 87% | 1.47 | 77% |
| ERV L | 0.73 | 1.73 | 42% | 0.18 | 10% | ||
| RV/TLC % | 29 | 19 | 37 | 28 | 102% | 35 | 126% |
| FEV1 L | 3.07 | 3.32 | 5.00 | 4.16 | 74% | ||
| FVC L | 4.04 | 4.03 | 6.03 | 5.03 | 80% | ||
| FEV1/VC %# | 74 | 69 | 92 | 81 | 94% | ||
| PEF L·s−1 | 8.11 | 7.59 | 11.57 | 9.58 | 85% | ||
| FEF25% L·s−1 | 6.93 | 5.44 | 11.06 | 8.25 | 84% | ||
| FEF50% L·s−1 | 3.52 | 3.14 | 7.48 | 5.31 | 66% | ||
| FEF75% L·s−1 | 0.91 | 1.11 | 3.67 | 2.39 | 38% | ||
LLN: lower limit of normality; ULN: upper limit of normality; VC: vital capacity; TLC: total lung capacity; FRC: functional residual capacity; IC: inspiratory capacity; RV: residual volume; ERV: expiratory reserve volume; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; PEF: peak expiratory flow; FEFx%: forced expiratory flow measured after x% of the FVC has been exhaled. #: spirometric evidence of an obstructive ventilatory defect as defined by a reduced FEV1/VC ratio less than the fifth percentile of the predicted value [1].