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Lung clearance index and moment ratios at different cut-off values in infant multiple-breath washout measurements


Egger, Barbara; Jost, Kerstin; Anagnostopoulou, Pinelopi; Yammine, Sophie; Singer, Florian; Casaulta, Carmen; Frey, Urs; Latzin, Philipp (2016). Lung clearance index and moment ratios at different cut-off values in infant multiple-breath washout measurements. Pediatric Pulmonology, 51(12):1373-1381.

Abstract

BACKGROUND: Multiple-breath washout (MBW) is increasingly used for infant lung function testing. Current guidelines recommend calculating lung clearance index (LCI) and functional residual capacity (FRC) at 2.5% of normalized tracer gas concentration, without clear recommendation for moment ratios (MR). Whether the 2.5% cut-off has the highest discriminative power to detect ventilation inhomogeneity in infants with lung diseases is unknown.
METHODS: We used sulfur-hexafluoride MBW measurements from 32 infants with cystic fibrosis, 32 preterm infants, and 32 healthy controls at postmenstrual age of 41-54 weeks. We compared the discriminative power to detect pathological values above the upper limit of normal for 12 different cut-offs between 20% and 1.5% for first and second MR (MR1, MR2), LCI, and FRC.
RESULTS: MR and LCI results changed significantly at different cut-offs. Mean MR2 in infants with cystic fibrosis increased from 2.4 to 7.2 units between 20% and 1.5% SF6 . The ability of MR and LCI to discriminate between health and disease increased significantly with lower cut-offs. The 1.5% cut-off showed highest discriminative power: in infants with cystic fibrosis pathological MR2 values were found in 27 out of 89 (30%) and for LCI in 28/89 (32%). In preterm infants, pathological MR2 values were detected in 39 out of 73 (53%), and for LCI in 35/73 (48%). FRC remained stable throughout the washout.
CONCLUSION: In infants, the diagnostic performance of MBW strongly depends on the point of analysis. The cut-off with the highest discriminative power to detect ventilation inhomogeneity in infants with cystic fibrosis and after preterm birth was at 1.5% tracer gas concentration. Pediatr Pulmonol. 2016;51:1373-1381. © 2016 Wiley Periodicals, Inc.

Abstract

BACKGROUND: Multiple-breath washout (MBW) is increasingly used for infant lung function testing. Current guidelines recommend calculating lung clearance index (LCI) and functional residual capacity (FRC) at 2.5% of normalized tracer gas concentration, without clear recommendation for moment ratios (MR). Whether the 2.5% cut-off has the highest discriminative power to detect ventilation inhomogeneity in infants with lung diseases is unknown.
METHODS: We used sulfur-hexafluoride MBW measurements from 32 infants with cystic fibrosis, 32 preterm infants, and 32 healthy controls at postmenstrual age of 41-54 weeks. We compared the discriminative power to detect pathological values above the upper limit of normal for 12 different cut-offs between 20% and 1.5% for first and second MR (MR1, MR2), LCI, and FRC.
RESULTS: MR and LCI results changed significantly at different cut-offs. Mean MR2 in infants with cystic fibrosis increased from 2.4 to 7.2 units between 20% and 1.5% SF6 . The ability of MR and LCI to discriminate between health and disease increased significantly with lower cut-offs. The 1.5% cut-off showed highest discriminative power: in infants with cystic fibrosis pathological MR2 values were found in 27 out of 89 (30%) and for LCI in 28/89 (32%). In preterm infants, pathological MR2 values were detected in 39 out of 73 (53%), and for LCI in 35/73 (48%). FRC remained stable throughout the washout.
CONCLUSION: In infants, the diagnostic performance of MBW strongly depends on the point of analysis. The cut-off with the highest discriminative power to detect ventilation inhomogeneity in infants with cystic fibrosis and after preterm birth was at 1.5% tracer gas concentration. Pediatr Pulmonol. 2016;51:1373-1381. © 2016 Wiley Periodicals, Inc.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Children's Hospital Zurich > Medical Clinic
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:December 2016
Deposited On:10 Feb 2017 09:33
Last Modified:08 Dec 2017 23:15
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:1099-0496
Publisher DOI:https://doi.org/10.1002/ppul.23483
PubMed ID:27214661

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