Alterations in Pulmonary Function in Different Respiratory Disease Categories
| TLC | RV | VC | FEV1/FVC | |
|---|---|---|---|---|
| Obstructive | N to ↑ | ↑ | ↓ | ↓ |
| Restrictive | ||||
| Pulmonary parenchymal | ↓ | ↓ | ↓ | N to ↑ |
| Extraparenchymal—neuromuscular weakness | ↓ | Variable | ↓ | Variable |
| Extraparenchymal—chest wall deformity | ↓ | Variable | ↓ | N |
Abbreviations: FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; N, normal; RV, residual volume.