TY - JOUR T1 - Phase 3 slope indices:can accurate estimates be obtained from 2 tests? JF - European Respiratory Journal JO - Eur Respir J VL - 44 IS - Suppl 58 SP - P1156 AU - Noor AL-Khathlan AU - Manjith Narayanan AU - Erol Gaillard AU - Caroline Beardsmore Y1 - 2014/09/01 UR - http://erj.ersjournals.com/content/44/Suppl_58/P1156.abstract N2 - Introduction:Multiple-breath washout (MBW) has a time-consuming protocol requiring 3 technically acceptable runs. Lung clearance index based on only 2 runs is as robust as that based on 3.1,2 We assessed whether accurate estimates of conductive and acinar ventilatory heterogeneity (Scond and Sacin) can be obtained from 2 runs. Method:We analysed N2MBW data from 119 school-age children (35with CF). All performed N2MBW in triplicate with a pre-set target Vt. Volume corrected Scond and Sacin from 3 tests (S3tests) were compared to that of the first two tests (S2tests) using Bland-Altman plots. The mean difference (Sdiff) was calculated as meanS3tests- meanS2tests. The sensitivity were determined using upper limits of normal (ULN) from our healthy controls. Results:There was no significant difference in Sconddiff or Sacindiff for the whole population. The mean (95%LA) was 0.0(0.02,-0.02) and 0.0(0.03,-0.03) for Sconddiff and Sacindiff respectively. There was a statistically significant difference in Sacindiff for healthy subjects (mean (95%LA) -0.002(0.02,-0.03,P=0.03). Among the CF patients, 15 had mean Scond3tests above ULN and 15 had mean Scond2tests above ULN (13 patients in common). The sensitivity was identical for Sacin. Concordance of classification occurred in 31(88.5%) subjects. Conclusion:Robust estimates of Scond and Sacin can be obtained from 2 tests without compromising sensitivity in CF. In healthy subjects, the difference in Sacin was ∼2.8% of published normal values3 and not clinically significant. The shortened protocol promotes the incorporation of MBW in a clinical context. Ref: 1Yammine et al. Thorax 2013;68:586, 2Robinson et al.Ped Pulm2013;48:336, 3Yammine et al JCF 2014;13:190. ER -