Scripties UMCG - Rijksuniversiteit Groningen
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De SMALL-studie: een vergelijking tussen de LCI en andere longfunctie testen

(2017) Wiesenekker, E. (Evelyne)

Background: The Multiple Breath Washout (MBW) test has proven itself as a test that reflects peripheral airway function. Nowadays two commercial MBW devices are available, EasyOne Pro LAB (NDD, Medical Technologies, Switzerland) (EOP) and Exhalyzer D (EcoMedics, AG, Switzerland) (ExD). There is limited information available about how well these devices measure the ventilation inhomogeneity in health and disease in relation to each other and other lung function tests. Reliability studies show conflicting results between the two devices and when compared to other lung function tests that measure FRC, like body plethysmography and helium dilution technique.
Objective: The aim of the present study is to compare the parameters obtained with MBW testing on EOP and ExD with each other in healthy adults and children. Secondary aims are to compare the commercial devices with widely used lung function tests that measure FRC and to compare parameters of the MBW method of CF patients to healthy children.
Methods: Healthy volunteers and CF patients were recruited between 08-2016 and 03-2017. MBW was performed with nitrogen (N2) as tracer gas. Subjects underwent MBW with EOP and ExD during two study days with different breathing protocols in a randomized setting. Spirometry, heliumdilution technique and body plethysmography were subsequently performed in each subject. CF-patients underwent MBW, spirometry and body plethysmography.
Results: 12 healthy adults (19.1-63.7 years), 11 healthy children (6.1-16.2 years) and 10 CF-patients (6,7-17,1 years) were included for analysis. EOP measured lower FRC than ExD with an average of 10,28%. LCI showed no significant difference between EOP and ExD in both adults and children at group level, although individual analysis showed little agreement. FRCEOP showed a good agreement with FRCHe and FRCpleth of <10% in both adults and children. There was little agreement between FRCExD and FRCHe, with a mean difference of 14,14%. In addition, FRCExD was measured higher than FRCpleth with a mean difference of 5,26%. LCI was higher in CF patients compared to healthy controls with a mean LCI (range) of 12,00 (7,51-15,15) and 7,00 (6,41-7,34) (p <0.05) respectively.
Conclusion/discussion: Based on the outcomes of this study the results of MBW measurement on EOP and ExD are not interchangeable. In this study the peripheral airway function is measured in a more reliable way by EOP than ExD when compared to helium dilution technique and body plethysmography. Based on the higher FRC measured on ExD compared to body plethysmography a technical or algorithmic problem seems to exist in ExD. This should be explored further. Finally, we confirmed that the small airways of patients with CF have already been affected during childhood.

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