Multiple breath inert gas washout as a measure of ventilation distribution in children with cystic fibrosis

Abstract

Background: Multiple breath inert gas washout (MBW) has been suggested as a tool for detecting early cystic fibrosis (CF) lung disease. A study was undertaken to compare the relative sensitivity of MBW and spirometry for detecting abnormal lung function in school age children with CF and to compare MBW results obtained from healthy children in the UK with those recently reported from Sweden. Methods: Forced expiratory volume in 1 second (FEV 1 ) and maximal expiratory flow when 25% of forced vital capacity remains to be expired (MEF 25 ) were compared with the lung clearance index (LCI) derived from sulphur hexafluoride MBW in 22 children with CF aged 6-16 years and in 33 healthy controls. Results: LCI was higher in children with CF than in healthy controls (mean difference 5.1 (95% CI of difference 4.1 to 6.1) and FEV 1 and MEF 25 z-scores were lower (mean difference 22.3 (95% CI 22.9 to 21.7) and 21.8 (95% CI 22.4 to 21.3), respectively; p,0.001 for all). There was a significant negative correlation between LCI and FEV 1 (r 2 = 0.62) and MEF 25 (r 2 = 0.46). However, while normal (>21.96 z-scores) FEV 1 and MEF 25 results were seen in 11 (50%) and 12 (53%) children with CF, respectively, all but one of these children had an abnormally increased LCI. LCI was repeatable in both groups (within subject CV for three measurements 6% for CF and 5% for healthy children). In healthy subjects LCI was independent of age and virtually identical in the British and Swedish children (mean difference 0.1 (95% CI 20.1 to 0.4), p = 0.38) Conclusions: MBW is reproducible between laboratories, generates normal ranges which are constant over childhood, and is more frequently abnormal than spirometry in children with CF.

Is Lung Clearance Index (LCI) Affected by the Severity of Lung Disease in CF?

“…A lot of studies have suggested that LCI has the advantage over FEV 1 to detect CF lung disease in earlier stages [21,36,38,[64][65][66][67][68]. A more sophisticated analysis of the SnIII has revealed the Scond and Sacin, as indices to detect the mechanisms of ventilation inhomogeneity and the location of the different ventilated lung units.…”

Chest health surveillance utility in the early detection of bronchiolitis obliterans syndrome in children after allo-SCT

“…Our results suggest that only PFTs are reliable to diagnose BOS early and may identify potential asymptomatic patients, and that in those who cannot undergo PFT, especially young children, novel alternative techniques such as multiple-breath washout testing needs to be explored. 15,16 As our understanding about the pathophysiology of BOS is improving, and more patients are surviving longer after SCT with GVHD, The National Institutes of Health consensus group recommends consideration of PFTs or spirometry every 3 months during the first year after transplantation in high-risk patients (patients with chronic GVHD). 12 Regular PFTs in the first year after SCT should allow the capture of subtle changes in lung volumes during a period of tapering immunosuppressant agents when most cases of BOS will start to develop and thus allow an opportunity for earlier and most effective intervention.…”

Assessment of hyperpolarized 3He lung MRI for regional evaluation of interventional therapy: A pilot study in pediatric cystic fibrosis

“…Assessing change over time and response to intervention is costly and generally relies on traditional spirometry, which is insensitive (30). More complex global lung function tests based on inert gas washout have been suggested to be sensitive to regional lung ventilation heterogeneity in pediatric CF (8,30,31); however, the use of these methods is no more widespread than 3 He MRI and their regional sensitivity is intrinsically less than an imagingbased method. CT and anatomical 1 H MRI have been shown to be sensitive to signs of CF lung disease (12) but neither have been shown to be sensitive to regional mucus shifting following physiotherapy.…”