Multiple breath washout testing in adults with pulmonary disease and healthy controls – can fewer measurements eventually be more?

Abstract

BackgroundMultiple breath washout (MBW) became a valuable research tool assessing ventilation heterogeneity. However, routine clinical application still faces several challenges. Deriving MBW parameters from three technically acceptable measurements according to current recommendations prolongs test times. We therefore aimed to evaluate reporting only duplicate measurements in healthy adults and pulmonary disease.MethodsOne hundred and fifty-three subjects prospectively underwent conventional lung function testing and closed-circuit SF6-MBW. Three technically acceptable MBW-measurements were obtained in 103 subjects.ResultsLung clearance index (LCI) differed significantly among 19 controls (7.4 ± 0.8), 19 patients with sarcoidosis (8.1 ± 1.2), 32 with bronchial asthma (9.2 ± 1.9) and 33 with COPD (10.8 ± 2.2, p < 0.001). Within-test repeatability was high (coefficient of variation between 2.5% in controls and 3.6% in COPD) and remained unchanged when only including the first two measurements. Likewise, LCI remained stable with mean absolute changes ranging from 0.9 ± 0.8% in controls to 1.5 ± 0.9% in COPD (p = 0.1). Mean test time reduction differed significantly between groups reaching 200 s in COPD (p = 0.01).ConclusionsDuplicate SF6-MBW-measurements are sufficient in adult patients with pulmonary disease and healthy controls. LCI values and intra-test repeatability are not affected reducing total test time statistically significant. Our findings have the potential to further facilitate application of MBW in research and clinical routine.Trial registration NCT03176745, June 2, 2017 retrospectively registered.Electronic supplementary materialThe online version of this article (10.1186/s12890-017-0543-y) contains supplementary material, which is available to authorized users.

Feasibility and clinical applications of multiple breath wash-out (MBW) testing using sulphur hexafluoride in adults with bronchial asthma

“…However, sensitivity was found to be lower in adult asthmatic patients as compared to MBW and may therefore be a marker of more severe disease 62 . Within-test repeatability found in our study is comparable to previously published data in stable adults showing CVs between 2.5 and 4.5% for LCI using SF 6 as tracer gas 37,39,63,64 . When paediatric populations are investigated, CV tends to be slightly higher ranging from 3.2 to 8.5% 50,54,65 .…”

“…Even in absence of spirometric obstruction, LCI was already pathologically altered 22 . Differences in FRC as measured by plethysmography and MBW were described previously in patients with obstructive lung disease 39,47,48 . When using an exogenous tracer gas such as SF 6 , these can be easily explained as only ventilated areas will contribute to FRC determination.…”

“…The coefficient of variation (CV) was calculated as SD/mean from two or three valid MBW measurements, respectively. Sample size calculation was based on previously published data 39 . An overall cohort of 60 subjects would provide 95% power to detect a 1.8 ± 0.4 difference in LCI with a 2:1 allocation of patients and non-asthmatic controls, respectively.…”

“…In clinical and scientific routine, several metrological aspects should be considered. Recently, it was demonstrated that duplicate LCI measurements are sufficient in adults 39 and preschool children 50 . Intra-test repeatability is not affected while total test time is reduced significantly.…”

ERS International Congress, Madrid, 2019: highlights from the Airway Diseases, Asthma and COPD Assembly

“…As such, some patients were found to be hyperresponsive to mannitol using the forced oscillation technique (FOT) while FEV 1 measurement did not show a response [85]. Using MBW, TRINKMANN et al [86] were able to differentiate between adult healthy controls and asthmatic patients, with some asthmatic patients having normal spirometry but abnormal sulfur hexafluoride MBW readings [87]. Alternatively, previous studies pointed out that SAD could be an early change in asthma prior to spirometric alterations [88].…”