Pulmonary function and cardiopulmonary exercise tests
| Respiratory limitation n=28 (54.9%) | O2 delivery/utilisation impairment or normal n=8 (15.7%) | Dysfunctional breathing n=15 (29.4%) | P value | |
| Time from diagnosis to PFTs and CPET, days median (25th–75th) | 58 (45–84) | 110 (76–196) | 153 (115–234) | <0.001 |
| PFTs and ABG | ||||
| FEV1 % predicted, median (25th–75th) | 75 (63–87) | 99 (87–107) | 98 (86–108) | 0.002 |
| FVC % predicted, median (25th–75th) | 70 (63–84) | 98.5 (87–107) | 103 (95–106) | <0.001 |
| TLCO % predicted, median (25th–75th) | 42 (34–49) | 71 (60–88) | 85 (64–92) | <0.001 |
| TLC % predicted, median (25th–75th) | 72 (63–85) | 99 (86–108) | 106 (95–110) | <0.001 |
| pH, median (25th–75th) | 7.43 (7.41–7.45) | 7.43 (7.40–7.44) | 7.43 (7.41–7.45) | 0.840 |
| PaO2, kPa, median (25th–75th) | 9.4 (8.5–10.3) | 11.5 (10.4–12.6) | 12.0 (10.6–12.4) | <0.001 |
| PaCO2, kPa, median (25th–75th) | 4.6 (4.1–5.0) | 4.7 (4.6–5.0) | 4.7 (4.5–4.9) | 0.889 |
| 6MWD, m, median (25th-75th) | 403 (337–439) | 480 (375–525) | 546 (520–600) | 0.012 |
| CPET | ||||
| Peak V’O2 mL/min/kg, median (25th–75th) | 13.3 (10.2–16.4) | 15.2 (13.7–20.5) | 22.9 (20.0–25.5) | <0.001 |
| Peak V’O2 % predicted | 53 (40–72) | 65 (59–84) | 87 (81–101) | 0.002 |
| Workload, W, median (25th-75th) | 90 (60–113) | 117 (86–189) | 158 (126–174) | <0.001 |
| Breathing reserve %, median (25th–75th) | 22 (10–37) | 47 (29–52) | 29 (23–37) | 0.189 |
| V’E/V’CO2 slope, median (25th–75th) | 39.8 (37.6–45.1) | 30.3 (26.5–32.1) | 31.6 (26.2–39.0) | 0.016 |
| Anaerobic threshold % of predicted V’O2 max, median (25th–75th) | 44 (27–51) | 44 (39–51) | 53 (49–67) | 0.012 |
| SpO2 at peak %, median (25th–75th) | 88 (84–92) | 95 (91–95) | 95 (94–97) | <0.001 |
| PaO2 at peak (kPa), median (25th–75th) | 8.4 (7.1–9.4) | 12.8 (12.5–13.3) | 12.6 (12.2–14.7) | <0.001 |
| VD/VT ratio at peak, median (25th–75th) | 0.40 (0.36–0.44) | 0.24 (0.18–0.31) | 0.22 (0.20–0.24) | 0.002 |
| Peak heart rate bpm, median (25th–75th) | 129 (115–144) | 152 (128–171) | 152 (144–176) | 0.004 |
| OUES slope, median (25th–75th) | 1.23 (0.92–1.79) | 1.43 (1.11–1.79) | 2.06 (1.51–2.43) | 0.274 |
6MWD 6 min walk distance, CPET, cardiopulmonary exercise tests; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; OUES, oxygen uptake extraction slope; PFT, pulmonary function tests; TLCO, transfer capacity for carbon monoxide; VD/VT, dead volume/tidal volume; V’O2, oxygen consumption V’E/V’CO2 ventilatory efficiency.