RT Journal Article
SR Electronic
T1 Alveolar lung clearance index: An alternative multiple breath washout outcome in children
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP P4528
VO 44
IS Suppl 58
A1 Sanja Stanojevic
A1 Renee Jensen
A1 Anouk Bensler
A1 Felix Ratjen
YR 2014
UL http://erj.ersjournals.com/content/44/Suppl_58/P4528.abstract
AB Background: Higher lung clearance index (LCI) values observed on the Ecomedics Multiple Breath Nitrogen Washout (N2MBW) relative to the respiratory mass spectrometry MBW (SF6MBW), may be partially explained by larger equipment dead space of the N2MBW (58.2 versus 15.4 ml). In this study we investigate whether calculation of alveolar LCI (aLCI), whereby airways dead space is accounted for, results in LCI values that more closely agree between the two systems.Methods: 50 healthy children and 42 children with CF (6 to 18 years) had both N2MBW and SF6MBW measured on the same test occasion. Standard LCI (sLCI) was calculated by correcting for total equipment dead space. In addition, we calculated alveolar LCI (aLCI), whereby calculations corrected for airways dead space (from the first breath of the washout using the Fowler method) and equipment dead space. The average sLCI and aLCI were calculated from all good quality trials, and compared.Results: On average aLCI was lower than sLCI on both the N2 (aLCI=7.6(SD=3.1), sLCI =9.0(3.6)) and SF6 (aLCI=7.2(2.7), sLCI=8.1(2.9)) systems. The difference in aLCI (Δ=-0.62(1.0)) between N2MBW and SF6MBW was in the opposite direction to that observed for sLCI (Δ= 0.77 (1.1)) which is likely due to the underestimation of FRC by SF6MBW (Jensen et al., 2013). The magnitude of the differences between systems was greater in CF than in health.Conclusions: These results suggest that higher LCI values measured by N2MBW may be partially explained by the larger equipment dead space relative to SF6MBW. This may be especially relevant in young children, where the ratio of equipment dead space to tidal volumes is high.Funded by CF Foundation, Irwin Family Foundation.