Patient data comparing physiological changes following initiation of NIV
| Characteristic | Pure obesity | Overlap syndrome | ||
| Pre-NIV | Post-NIV | Pre-NIV | Post-NIV | |
| BMI (kg/m2) | 54 | 50 | 43 | 39 |
| Weight (kg) | 146 | 134 | 112 | 103 |
| Po2 (kPa) | 6.2 | 8.34 | 6.6 | 7.2 |
| Pco2 (kPa) | 8.4 | 6.0 | 7.8 | 6.0 |
| FEV1 (% pred) | 73.0 | 75.0 | 40.6 | 53.1 |
| FVC (% pred) | 79.0 | 85.0 | 56.0 | 72.9 |
| FEV1/FVC (%) | 75.9 | 71.4 | 58.7 | 59.1 |
| FRC (% pred) | 66.0 | 77.8 | 97.9 | 112.3 |
| TLC (% pred) | 81.0 | 85.2 | 81.1 | 94.4 |
| RV (% pred) | 86.6 | 92.0 | 118.4 | 130.7 |
| Tlco (% pred) | 97.2 | 91.5 | 74.3 | 69.2 |
| Kco (% pred) | 123.5 | 113.2 | 107.5 | 99.5 |
BMI, body mass index; FEV1, forced expiratory volume in 1 s; FRC, functional residual capacity; FVC, forced vital capacity; Kco, carbon monoxide transfer coefficient; NIV, non-invasive ventilation; Pco2, Po2, carbon monoxide and oxygen tensions; RV, residual volume; TLC, total lung capacity; Tlco, carbon monoxide lung transfer factor.