Load, drive, and capacity in the various conditions treated with non-invasive ventilation (NIV)
| Load | Drive | Capacity | |
| NMD | Increased: • due to atelectasis • upper airway resistance in some conditions due to bulbar weakness | No abnormality | Reduced: • intrinsic weakness of respiratory muscles |
| CWD | Increased: • reduced chest wall compliance • reduced lung compliance | No abnormality | Reduced: • mechanical disadvantage |
| COPD | Increased: • airways obstruction • intrinsic PEEP | No abnormality | Reduced: • mechanical disadvantage secondary to hyperinflation |
| Central hypoventilation | No abnormality | Markedly reduced | No abnormality |
NMD = neuromuscular disease; CWD = chest wall deformity; COPD = chronic obstructive pulmonary disease.