@article {EggerPA1268, author = {Barbara Egger and Sophie Yammine and Anne Schmidt and Urs Frey and Philipp Latzin}, title = {LCI and Moment ratios (MR) at different tracer cut-offs in infant multiple-breath-washout measurements}, volume = {46}, number = {suppl 59}, elocation-id = {PA1268}, year = {2015}, doi = {10.1183/13993003.congress-2015.PA1268}, publisher = {European Respiratory Society}, abstract = {Background: Multiple breath washout (MBW) is used to measure peripheral ventilation inhomogeneity. ERS/ATS guidelines recommend calculating the lung clearance index (LCI) at 2.5\% of tracer gas concentration, without clear recommendation for MR. Whether this arbitrary cut-off is best suited to detect lung disease in infants is unknown.Aim: To compare LCI and MR results at different cut-off concentrations in infants with lung diseases.Methods: We used sulphur-hexafluoride (SF6)-MBW measurements from 20 infants with cystic fibrosis (CF) and 18 preterm infants (PT) with different degrees of ventilation inhomogeneity and 20 healthy controls (HC) at the age of 4-6 weeks. We compared sensitivity of different end-concentrations between 5\% and 1\% for LCI and MR2 to detect pathological values above the upper limit of normal derived from HC.Results: As known for LCI, MR results change significantly at different cut-off values. Mean MR2 in CF infants e.g. increases from 5.1 to 8.3 units between 5\% and 1.5\%.In general, cut-offs between 4\% and 2\% showed the highest sensitivity to detect abnormal lung function. In CF, 21 out of 40 LCI and 20 out of 39 MR2 results were abnormal at 2.5\% and 2\%, respectively. In PT, 26 out of 36 LCI and MR2 measurements were abnormal at the 3\% cut-off.Conclusion: In contrast to FRC, both LCI and MR results depend dramatically on cut-off values. As the most sensitive cut-off in both patient groups lies around 2.5\%, it does not seem to be necessary to wash out until 0\%. Using the current recommendations, a large proportion of CF and PT infants shows abnormal values for LCI and MR2. Slight differences between disease groups need to be examined in larger samples.}, issn = {0903-1936}, URL = {https://erj.ersjournals.com/content/46/suppl_59/PA1268}, eprint = {https://erj.ersjournals.com/content}, journal = {European Respiratory Journal} }