Data from the shortened multiple breath washout
| LCI | ULN | Abnormal n/N | Correctly categorised % | Mean (range) time saved s | Mean time saved % | Mean intra-test CV (%) | |||||||||
| Asthma | CF | PCD | Asthma | CF | PCD | Asthma | CF | PCD | Asthma | CF | PCD | LCI | FRC | ||
| LCIstd | 7.30 | 5/21 | 15/20 | 17/19 | 4.7 | 5.2 | |||||||||
| LCI0.75 | 6.18 | 2/21 | 14/20 | 16/19 | 90.5 | 95 | 100 | 17 (5–49) | 21 (4–47) | 22 (6–68) | 18 | 17 | 22 | 5.1 | 5.2 |
| LCI0.5 | 5.60 | 3/21 | 13/20 | 14/19 | 90.5 | 90 | 94.7 | 26 (9–67) | 26 (6–69) | 36 (16–82) | 26 | 27 | 28 | 5.4 | 5.4 |
| LCI0.25 | 5.03 | 3/21 | 12/20 | 11/19 | 90.5 | 85 | 94.7 | 33 (11–67) | 39 (14–83) | 47 (18–97) | 34 | 36 | 41 | 5.3 | 5.5 |
School age children with asthma (n=21), cystic fibrosis (CF) (n=20) and primary ciliary dyskinesia (PCD) (n=19) completed a minimum of two SF6 multiple breath washouts per child. Upper limit of normal (ULN) lung clearance index (LCI) (mean+sd*1.96) calculated from healthy controls. Correctly categorised data was calculated as a percentage of the correctly predicted values using the ULN. Coefficient of variance (CV) calculated from the mean of the coefficient of variance of the intra-test functional residual capacity (FRC) and LCI (sd/mean). Time saved in each of the shortened MBWs is to their respective end-points. LCIstd had a mean duration of 69 s in healthy controls (range 34–119), 93 s in asthma (range 50–144), 97 s in CF (range 41–150) and 114 s in PCD (range 54–203). LCIstd: 1/40 of the initial concentration of tracer gas; LCI0.75: 1/30 of the initial concentration of tracer gas; LCI0.5: 1/20 of the initial concentration of tracer gas; LCI0.25: 1/10 of the initial concentration of tracer gas.