Alternate gas washout indices: Assessment of ventilation inhomogeneity in mild to moderate pediatric cystic fibrosis lung disease

Nyilas, Sylvia; Bigler, Anja; Yammine, Sophie; Kieninger, Elisabeth; Rochat, Isabelle; Ramsey, Kathryn; Casaulta, Carmen; Moeller, Alexander; Latzin, Philipp; Singer, Florian

doi:10.1002/ppul.24149

Cited by 6 publications

(7 citation statements)

References 29 publications

(84 reference statements)

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“…Practitioners should be aware that VI can in fact be reduced pathologically, not in CF disease, but we have experienced with some of our preterm children. Comparison of MBW results in our CF cohort with those of previous studies 1,2,13,16‐23 (E‐table 1) is complicated by differences in tracer gas, devices and settings used as well as in the age range and inclusion criteria of the study populations. For instance, the impact of using a different tracer gas (N 2 vs SF 6 ) is well documented for LCI 24‐27 .…”

Section: Discussionmentioning

confidence: 90%

Limitations of regional ventilation inhomogeneity indices in children with cystic fibrosis

Verger¹,

Arigliani

Raywood³

et al. 2020

Pediatric Pulmonology

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Background Scond is a multiple breath washout (MBW) index that measures convection‐dependent ventilation inhomogeneity (CDI) arising within conductive airways, but the calculation method is unreliable in subjects with advanced cystic fibrosis (CF) lung disease. A new CDI index, Scond*, has been proposed for use in adults with CF and moderate to severe ventilation inhomogeneity. We aimed to evaluate the most appropriate CDI index in children and adolescents with CF and various degrees of inhomogeneity, and from that the most appropriate diffusion‐convection‐interaction index (Sacin or Sacin*). Methods Scond, Sacin and the alternative indices, Scond*, and Sacin* were retrospectively calculated in subjects with CF aged 3 to 18 years and age‐matched controls, who underwent sulfur hexafluoride MBW between 2003 and 2015. The upper limit of normal was based on 95th percentile of the control population. Results One hundred and twenty‐seven subjects with CF (44% male; mean age ± SD: 7.5 years ± 4.9) and 94 controls (53% male; 7.9 years ± 5.1) were included in the final analysis. All measures of ventilation inhomogeneity were significantly higher in children with CF. As predicted, Scond reached a maximum value at lung clearance index (LCI) values of approximately 9. In subjects with LCI ≥ 9 Scond* showed good correlation with LCI, whilst Scond had no relationship with LCI (Spearman rank correlation Scond*/LCI, 0.49; P < .01; Scond/LCI, −0.068; P = .46). In subjects with mild disease (LCI < 9) Scond was more frequently abnormal than Scond* (37% vs 16%; P = .01). Conclusions Scond and Sacin are sensitive indices of early regional inhomogeneity, but are of no value when LCI ≥ 9. In these subjects, Scond* & Sacin* are potential alternatives.

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Section: Discussionmentioning

confidence: 90%

Limitations of regional ventilation inhomogeneity indices in children with cystic fibrosis

Verger¹,

Arigliani

Raywood³

et al. 2020

Pediatric Pulmonology

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“…The assumption is supported by the alternate indices moment ratios and Scond which estimate global and convection-dependent ventilation inhomogeneity, respectively. Impaired diffusion-convection-dependent ventilation inhomogeneity measured by Sacin seems rare in mild CF lung disease [25] . This supports the utility of LCI as a global measure of lung function in mild CF lung disease and confirms the lack of sensitivity by the other biomarkers such as FEV 1 , FEF 25-75 and Sacin.…”

Section: Discussionmentioning

confidence: 93%

“…For sample size estimation, we hypothesized that the difference between CFTR-MF and CFTR-RF in LCI is significantly lower compared to difference in LCI between individuals with CF and healthy controls [25] . For a two-sample comparison assuming two-sided alpha = 0.0500, power = 0.900, CFTR-RF prevalence of 10%, LCI mean (SD) = 10.0 (2.0) units in the CFTR-MF population and 8.0 (2.0) units in the CFTR-RF population, the required sample sizes would be 120 individuals with CFTR-MF and 12 with CFTR-RF.…”

Section: Variables and Sample Sizementioning

confidence: 99%

CFTR-function and ventilation inhomogeneity in individuals with cystic fibrosis

Bernasconi

Kieninger

Shaw

et al. 2021

Journal of Cystic Fibrosis

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“…Measurement of LCI has been found to be reliable, valid and responsive during treatment of pulmonary exacerbations and for monitoring disease progression [23,37,89,110]. Measurements obtained by N 2 washout and by SF 6 were comparable (limits of agreement −2.5 to 1.2) [23].…”

Section: Lung Function Testsmentioning

confidence: 99%

The measurement properties of tests and tools used in cystic fibrosis studies: a systematic review

et al. 2021

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There is no consensus on how best to measure responses to interventions among children and adults with cystic fibrosis (CF). We have systematically reviewed and summarised the characteristics and measurement properties of tests and tools that have been used to capture outcomes in studies among people with CF, including their reliability, validity and responsiveness. This review is intended to guide researchers when selecting tests or tools for measuring treatment effects in CF trials. A consensus set of these tests and tools could improve consistency in how outcomes are captured and thereby facilitate comparisons and synthesis of evidence across studies.

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Alternate gas washout indices: Assessment of ventilation inhomogeneity in mild to moderate pediatric cystic fibrosis lung disease

Abstract: In children with mild-to-moderate CF lung disease, alternate protocols seem practical but clinimetric properties of standard Sn protocols are preferable.

Cited by 6 publications

References 29 publications

Limitations of regional ventilation inhomogeneity indices in children with cystic fibrosis

Limitations of regional ventilation inhomogeneity indices in children with cystic fibrosis

CFTR-function and ventilation inhomogeneity in individuals with cystic fibrosis

The measurement properties of tests and tools used in cystic fibrosis studies: a systematic review

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