Repeatability and bronchodilator reversibility of lung function in young children

Abstract

Knowledge of short-and longer-term repeatability of lung function in health and disease is essential to determine bronchodilator reversibility thresholds and to recognise if changes in lung function represent disease progression, therapeutic intervention or normal variability.Multiple-breath washout indices (lung clearance index, conductive ventilation inhomogeneity (Scond)) and specific airway resistance (sRaw) were measured in healthy children and stable wheezers. Measurements were performed at baseline and after 20 min without intervention to assess repeatability and determine bronchodilator reversibility thresholds. Bronchodilator reversibility was assessed by repeating baseline measurements 20 min after inhaled salbutamol. 28 healthy controls, mean¡SD age 6.1¡0.7 years and 62 wheezers 5.4¡0.6 years were tested. Baseline variability in multiple-breath washout indices and sRaw was not significantly different between wheezers and healthy controls. Significant bronchodilator reversibility was only observed in wheezers for Scond (16%), but in both wheezers (37%) and healthy controls (20%) for sRaw. Some wheezers and healthy controls demonstrated increases in multiple-breath washout indices post-bronchodilator.Lung clearance index and sRaw demonstrate low baseline variability in healthy and diseased subjects. Neither multiple-breath washout indices nor sRaw are ideal for assessing bronchodilator reversibility in young children with stable wheeze. These findings will help to interpret the effect of therapeutic interventions in children with respiratory diseases. @ERSpublications Multiple-breath washout indices and sRaw do not reflect bronchodilator reversibility in young children with stable wheeze

Ventilation Heterogeneity and Airway Hyperreactivity in Children with Well Controlled Asthma

“…Ventilation heterogeneity within the lung is a well-recognized feature of asthma; however, relatively few studies have evaluated this measure in young asthmatic children [10,22,23]. In our study, we found that not only did young well-controlled children with asthma have higher LCI values when compared with healthy controls, but there was also a significant relationship between LCI and airway reactivity among the asthmatic children; increasing LCI was associated with greater airway reactivity.…”

Lung clearance index in cystic fibrosis subjects treated for pulmonary exacerbations

“…Recent studies would suggest that mucus plugging, and specifically large-airway mucus plugging changes more than other aspects of CF lung disease with antibiotic therapy [12,41]. In contrast, LCI is affected by heterogeneities at all levels of the airway tree, including peripheral airway disease, and changes in bronchomotor tone do not affect the measurement as much as FEV1, as demonstrated by studying LCI before and after administration of bronchodilators [42][43][44]. Previously closed compartments contributing to the measurement could also affect LCI response.…”

Inter-test reproducibility of the lung clearance index measured by multiple breath washout

“…Investigators report differing findings for the inter-test reproducibility of the LCI due to variability in protocol designs, study population and MBW methodology [5][6][7][8][9][10][11][12][13][14]. Most notably, time intervals between repeated tests range from hours to years, and none report reproducibility for time intervals typically used to clinically track patients with cystic fibrosis (e.g.…”

“…quarterly) [6,11,15]. Comparison between studies is further limited by the various methodologies that define reproducibility; coefficient of variation (%CV) [5,7,8], the intra-class correlation coefficient (ICC) [6], the limits of agreement from Bland-Altman plots [5,[9][10][11] or the coefficient of reproducibility [12,13]. Reproducibility has most commonly been reported as Bland-Altman limits of agreement or coefficient of repeatability.…”