Correlation between the forced expiratory volume in one second (FEV1) per cent predicted and normalised phase-III slopes (SnIII) at rest, after cold dry-air hyperventilation challenge (CACh), and after β2-agonist therapy, and between the changes in FEV1 % pred and the normalised phase-III slopes from baseline to postchallenge, in the whole study population, and in the three subgroups
All subjects | Subgroup | |||
Major responders | Minor responders | Nonresponders | ||
Subjects n | 55 | 12 | 16 | 27 |
Resting | ||||
FEV1 % pred vs | ||||
SF6 SnIII·L−1 | ns | ns | ns | ns |
He SnIII·L−1 | ns | ns | ns | ns |
(SF6-He) SnIII·L−1 | ns | ns | ns | ns |
Post-CACh | ||||
FEV1 % pred vs | ||||
SF6 SnIII·L−1 | 0.38 (<0.001) | 0.35 (0.044) | ns | ns |
He SnIII·L−1 | 0.48 (<0.001) | 0.55 (0.005) | ns | ns |
(SF6-He)·SnIII·L−1 | 0.23 (<0.001) | 0.33 (0.049) | ns | ns |
Post-β2 therapy | ||||
FEV1 % pred vs | ||||
SF6 SnIII·L−1 | ns | 0.51 (0.013) | ns | ns |
He SnIII·L−1 | ns | 0.60 (0.005) | ns | ns |
(SF6-He) SnIII·L−1 | ns | ns | ns | ns |
Change from resting to post-CACh | ||||
FEV1 % pred vs | ||||
SF6 SnIII·L−1 | 0.60 (<0.001) | ns | ns | ns |
He SnIII·L−1 | 0.70 (<0.001) | ns | ns | ns |
(SF6-He) SnIII·L−1 | 0.36 (0.001) | 0.50 (0.010) | 0.27 (0.040) | ns |
Data are presented as r2 (p-values) from the Pearson correlation test
vs: versus
SF6: sulphur hexafluoride
He: helium
ns: nonsignificant