Abstract
Background: Assessment of ILD includes measurement of vital capacity (VC) and transfer factor (TLCO). Although involvement of the peripheral airways is common, they are poorly represented in current diagnostics. Impulse oscillometry (IOS) and multiple breath washout (MBW) could be promising for assessing peripheral resistance and ventilation heterogeneity. We aimed to evaluate both techniques as compared to conventional lung function testing in ILD.
Methods: Body plethysmography, IOS and TLCO determination were performed in 44 participants. Lung clearance index (LCI) was calculated from sulfur hexafluoride MBW. Severity graduation was done according to ATS/ERS recommendations.
Results: 21 controls and 23 ILD patients were included (fibrosis n=10, sarcoidosis n=13). LCI was elevated in ILD and increased with restriction severity (ANOVA, p<0.001). Despite normal TLCO, LCI tended to be higher (7.5±0.2 vs 7.3±0.9) also increasing with TLCO impairment (ANOVA, p=0.001). In peripheral obstruction (IOS), LCI (9.8±2.2 vs 7.9±1.4, p=0.04) and sRtot (223±111 vs 80±29%, p<0.0001) were higher while FEV1%VC showed no difference (93±9 vs 96±11%, p=0.66).
Conclusion: LCI and IOS parameters are elevated in ILD and could provide additional information to conventional lung function testing in initial assessment and follow-up. Further studies should aim at a potential clinical benefit especially in early detection and at a refined graduation.
Control | ILD | p-value | |
VC [% predicted] | 102±14 | 85±24 | <0.01 |
FEV1%VC [% predicted] | 99±6 | 93±14 | 0.07 |
TLCO [% predicted] | 91±13 | 65±21 | <0.0001 |
R5 [% predicted] | 92±20 | 112±34 | 0.02 |
D5-20 [%] | 12±14 | 27±30 | 0.05 |
LCI | 7.3±0.9 | 8.8±1.6 | <0.001 |
TLC: total lung capacity, R5: resistance @5Hz, D5-20: frequency dependency of resistance |
- Copyright ©the authors 2016