BackgroundThe multiple breath nitrogen washout (N2MBW) technique is increasingly used to assess the degree of ventilation inhomogeneity in school-aged children with lung disease. However, reference values for healthy children are currently not available. The aim of this study was to generate reference values for N2MBW outcomes in a cohort of healthy Caucasian school-aged children.MethodsN2MBW data from healthy Caucasian school-age children between 6 and 18 years old were collected from four experienced centres. Measurements were performed using an ultrasonic flowmeter (Exhalyzer D, Eco Medics AG, Duernten, Switzerland) and were analysed with commercial software (Spiroware version 3.2.1, Eco Medics AG). Normative values and upper limits of normal (ULN) were generated for lung clearance index (LCI) at 2.5% (LCI2.5%) and at 5% (LCI5%) of the initial nitrogen concentration and for moment ratios (M1/M0 and M2/M0). A prediction equation was generated for functional residual capacity (FRC).ResultsAnalysis used 485 trials from 180 healthy Caucasian children aged from 6 to 18 years old. While LCI increased with age, this increase was negligible (0.04 units·year–1 for LCI2.5%) and therefore fixed ULN were defined for this age group. These limits were 7.91 for LCI2.5%, 5.73 for LCI5%, 1.75 for M1/M0 and 6.15 for M2/M0, respectively. Height and weight were found to be independent predictors of FRC.ConclusionWe report reference values for N2MBW outcomes measured on a commercially available ultrasonic flowmeter device (Exhalyzer D, Eco Medics AG) in healthy school-aged children to allow accurate interpretation of ventilation distribution outcomes and FRC in children with lung disease.
These data suggest that the lung clearance index may be a useful surveillance tool for monitoring the presence and extent of lower airway inflammation and infection in preschool children with cystic fibrosis.
It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online.
The lung clearance index (LCI) from the multiple-breath washout (MBW) test is a promising surveillance tool for pre-school children with cystic fibrosis (CF). Current guidelines for MBW testing recommend that three acceptable trials are required. However, success rates to achieve these criteria are low in children aged <7 years and feasibility may improve with modified pre-school criteria that accepts tests with two acceptable trials. This study aimed to determine if relationships between LCI and clinical outcomes of CF lung disease differ when only two acceptable MBW trials are assessed.Healthy children and children with CF aged 3–6 years were recruited for MBW testing. Children with CF also underwent bronchoalveolar lavage fluid collection and a chest computed tomography scan.MBW feasibility increased from 46% to 75% when tests with two trials were deemed acceptable compared with tests where three acceptable trials were required. Relationships between MBW outcomes and markers of pulmonary inflammation, infection and structural lung disease were not different between tests with three acceptable trials compared with tests with two acceptable trials.This study indicates that pre-school MBW data from two acceptable trials may provide sufficient information on ventilation distribution if three acceptable trials are not possible.
The multiple-breath nitrogen washout (MBN 2 W) test assesses ventilation distribution by determining the number of functional residual capacity (FRC) lung turnovers required for tidal breathing of 100% oxygen to wash out resident nitrogen from the lungs [1]. In particular, the test has gained significant interest as a tool for monitoring disease progression and prognosis in children with lung disease, with a specific focus on cystic fibrosis (CF) due to its ability to discriminate between health and disease [2]. The use of 100% oxygen has become the preferred choice of inert gas in older children and adults. However, as discussed in the European Respiratory Society/American Thoracic Society consensus statement, there are disadvantages and unknowns as to how patient age, sedation and sleep state may interact with 100% oxygen to alter breathing patterns [3]. It is known that 100% oxygen alters breathing patterns in infants [4, 5] and therefore this approach is not recommended in this age group; however, it is assumed that the effect of 100% oxygen on respiration is diminished beyond infancy [3], with no reported impact of 100% oxygen on breathing parameters in school-aged children [6]. It remains unknown whether hyperoxia affects tidal breathing in young children, as there are no published studies in this age range. This study aimed to determine whether breathing 100% oxygen altered tidal breathing parameters in healthy young children and young children with CF.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.