Pulmonary function tests (per cent of predicted) and blood gases
| Controlled asthma | Severe asthma | Controlled versus severe asthma | |
| Subjects n | 130 | 133–153# | |
| FEV1 | 88.5±18.1 | 71.8±23.1 | p<0.001 |
| FEV1 post salbutamol | 97.6±17.8 | 80.9±24.1 | p<0.001 |
| FVC | 103.1±16.1 | 94.1±21.1 | p<0.001 |
| FEV1/FVC | 89.7±12.8 | 79.9±16.6 | p<0.001 |
| TLC | 104.1±13.4 | 104.4±15.2 | ns |
| RV/TLC | 104.2±23.0 | 113.4±28.0 | p<0.01 |
| K CO | 95.0±16.7 | 90.6±19.0 | p<0.05 |
| Pa,O2 kPa | 12.0±1.6 | 11.2±1.9 | p<0.001 |
| Pa,CO2 kPa | 5.1±0.5 | 4.9±0.5 | p<0.01 |
| pH | 7.41±0.03 | 7.42±0.03 | ns |
| HCO3 mmol·L−1 | 24.8±2.4 | 24.3±2.4 | ns |
| Base excess mmol·L−1 | 0.7±2.3 | 0.4±2.2 | ns |
Data presented as mean±sd
FEV1: forced expiratory volume in one second
FVC: forced vital capacity
TLC: total lung capacity
ns: not significant
RV: residual volume
KCO: carbon monoxide transfer coefficient
Pa,O2: arterial oxygen tension
Pa,CO2: carbon dioxide arterial tension
#: Twenty subjects did not perform all spirometry measurements or blood gases