Baseline characteristics of the study population in relation to NOx
| NOx ≤10 μmol·L−1 | NOx >10 μmol·L−1 | p-value# | |
| Patients n | 56 | 48 | |
| Age years | 38 (27–45) | 44 (22–51) | 0.73 |
| Female | 15 (70) | 37 (77) | <0.001 |
| BMPR2 mutation | 15 (27) | 4 (9) | 0.02 |
| BMI kg·m−2 | 21 (19–23) | 22 (20–26) | 0.17 |
| WHO FC | 0.78 | ||
| Class II | 16 (29) | 16 (33) | |
| Class III | 33 (59) | 25 (52) | |
| Class IV | 7 (13) | 7 (15) | |
| Onset to diagnosis months | 24 (6–48) | 23 (8–65) | 0.65 |
| 6MWD m¶ | 383 (315–425) | 423 (290–445) | 0.47 |
| BNP pg·mL−1 | 226 (44–435) | 116 (20–341) | 0.70 |
| Haemodynamic variables | |||
| Heart rate bpm | 86 (76–95) | 84 (72–92) | 0.47 |
| mRAP mmHg | 7 (4–11) | 8 (6–14) | 0.69 |
| mPAP mmHg | 63 (53–67) | 61 (45–69) | 0.002 |
| PAWP mmHg | 9 (8–11) | 9 (6–10) | 0.26 |
| CO L·min−1 | 3.9 (3.3–5.0) | 4.2 (3.2–4.8) | 0.09 |
| CI L·min−1·m−2 | 2.4 (1.9–3.1) | 2.7 (2.2–3.2) | 0.07 |
| PVR Wood units | 14 (9–19) | 12 (8–17) | 0.002 |
| SvO2 % | 61 (55–67) | 63 (51–73) | 0.18 |
Data are presented as median (interquartile range) or n (%), unless otherwise stated. BMI: body mass index; WHO FC: World Health Organization functional class; 6MWD: 6-min walk distance; BNP: brain natriuretic peptide; mRAP: mean right atrial pressure; mPAP: mean pulmonary arterial pressure; PAWP: mean pulmonary artery wedge pressure; CO: cardiac output; CI: cardiac index; PVR: pulmonary vascular resistance; SvO2: mixed venous oxygen saturation. #: comparison between groups with nitrite (NO2−) plus nitrate (NO3−) (NOx) ≤10 μmol·L−1 and NOx >10 μmol·L−1; ¶: 6MWD could be successfully measured in 92 patients.