Lung Clearance Index (LCI) in Patients with Bronchiolitis Obliterans: A Preliminary Report and Comparison to Cystic Fibrosis Patients

Pulmonary Function in Post-Infectious Bronchiolitis Obliterans in Children: A Systematic Review and Meta-Analysis

Owing to the rarity of post-infectious bronchiolitis obliterans (PIBO), pulmonary function in children with PIBO has been mainly investigated in small-sample sized studies. This systematic review and meta-analysis investigated pulmonary function in children with PIBO, regardless of age at respiratory insult and PIBO diagnosis. A systematic literature search revealed 16 studies reporting pulmonary function data in 480 children with PIBO. Levels of key pulmonary function parameters were summarized by pooled mean difference (MD) only in children with PIBO, and a random effect model was used. Pooled MDs (95% confidence interval [CI]) for FEV₁, FVC, and FEF_25-75% were 51.4, (44.2 to 58.5), 68.4 (64.4 to 72.3), and 26.5 (19.3 to 33.6) % predicted, respectively, with FEV₁/FVC of 68.8% (62.2 to 75.4). Pooled MDs (95% CI) of the z-scores for FEV₁, FVC, and FEF_25-75% were -2.6 (-4.2 to -0.9), -1.9 (-3.2 to -0.5), and -2.0 (-3.6 to -0.4). Pooled MD (95% CI) for the diffusion capacity of the lungs for carbon monoxide from two studies was 64.9 (45.6 to 84.3) % predicted. The post-bronchodilator use change in the FEV₁ in three studies was 6.1 (4.9 to 7.2). There was considerable heterogeneity across the studies. PIBO is associated with moderately impaired pulmonary function, and this review facilitates an understanding of PIBO pathophysiology in children.

Multiple breath washout: A noninvasive tool for identifying lung disease in symptomatic military deployers

RATIONALE

Military deployments to austere environments since November 9, 2001 may put "deployers" at risk for respiratory disease. Sensitive, noninvasive tools for detecting large and small airways injury are needed to identify early disease and help inform management for this at-risk population.

OBJECTIVES

We examined multiple breath washout (MBW) as a tool for identifying deployment-related airways disease and assessed host and exposure risk factors compared to healthy controls.

METHODS

Between March 2015 and March 2020, 103 healthy controls and 71 symptomatic deployers with asthma and/or distal lung disease completed a questionnaire, spirometry and MBW testing. SAS v. 9.4 was used to compare MBW parameters between deployers and controls via univariate analyses and adjusted for demographic factors using multiple linear regression.

MEASUREMENTS AND MAIN RESULTS

Deployers were significantly more likely than controls to have an abnormal lung clearance index (LCI) score indicating global ventilation inhomogeneity. Adjusting for sex, smoking status, smoking pack-years and body mass index, LCI scores were significantly more abnormal among those with deployment-related asthma and distal lung disease compared to controls. The unadjusted variable Sacin (a marker of ventilation inhomogeneity in the acinar airways) was higher and thus more abnormal in those with both proximal and distal airways disease. Deployers who reported more frequent exposure to explosive blasts had significantly higher LCI scores.

CONCLUSIONS

This study demonstrates the utility of MBW in evaluating exposure-related airways disease in symptomatic military personnel following deployment to austere environments, and is the first to link exposure to explosive blasts to measurable small airways injury.

Pulmonary function testing in children's interstitial lung disease

The use of pulmonary function tests (PFTs) has been widely described in airway diseases like asthma and cystic fibrosis, but for children's interstitial lung disease (chILD), which encompasses a broad spectrum of pathologies, the usefulness of PFTs is still undetermined, despite widespread use in adult interstitial lung disease. A literature review was initiated by the COST/Enter chILD working group aiming to describe published studies, to identify gaps in knowledge and to propose future research goals in regard to spirometry, whole-body plethysmography, infant and pre-school PFTs, measurement of diffusing capacity, multiple breath washout and cardiopulmonary exercise tests in chILD. The search revealed a limited number of papers published in the past three decades, of which the majority were descriptive and did not report pulmonary function as the main outcome.PFTs may be useful in different stages of management of children with suspected or confirmed chILD, but the chILD spectrum is diverse and includes a heterogeneous patient group in all ages. Research studies in well-defined patient cohorts are needed to establish which PFT and outcomes are most relevant for diagnosis, evaluation of disease severity and course, and monitoring individual conditions both for improvement in clinical care and as end-points in future randomised controlled trials.

Exercise capacity in patients with cystic fibrosis vs. non-cystic fibrosis bronchiectasis

Background

Bronchiectasis is associated with morbidity, low exercise capacity and poor quality of life. There is a paucity of data on exercise capacity using cardiopulmonary exercise test (CPET) in non-cystic fibrosis (CF) bronchiectasis. Our aim was to compare exercise capacity using CPET in CF and non-CF bronchiectasis patients.

Methods

Cross-sectional retrospective/prospective controlled study assessing CPET using cycle ergometer. Exercise parameters and computed tomography (CT) findings were compared. Results: Hundred two patients with bronchiectasis and 88 controls were evaluated; 49 CF (age 19.7 ± 9.7 y/o, FEV₁%predicted 70.9 ± 20.5%) and 53 non-CF (18.6 ± 10.6 y/o, FEV₁%predicted 68.7 ± 21.5%). Peak oxygen uptake (peak V˙O2) was similar and relatively preserved in both groups (CF 1915.5±702.0; non-CF 1740±568; control 2111.0±748.3 mL/min). Breathing limitation was found in the two groups vs. control; low breathing reserve (49% in CF; 43% non-CF; 5% control) and increased V˙E/V˙CO2 (CF 31.4±4.1, non-CF 31.7±4.1 and control 27.2 ± 2.8). Oxygen pulse was lower in the non-CF; whereas a linear relationship between peak V˙O2 vs. FEV₁ and vs. FVC was found only for CF. CT score correlated with V˙E/V˙CO2 and negatively correlated with V˙O2/kg and post exercise oxygen saturation (SpO₂).

Conclusions

CPET parameters may differ between CF and non-CF bronchiectasis. However, normal exercise capacity may be found unrelated to the etiology of the bronchiectasis. Anatomical changes in CT are associated with functional finding of increased V˙E/V˙CO2 and decreased SpO₂. Larger longitudinal studies including cardiac assessment are needed to better study exercise capacity in different etiologies of non-CF bronchiectasis.

Trial registration

ClinicalTrials.gov, registration number: NCT03147651.

Six-minute walk, lung clearance index, and QOL in bronchiolitis obliterans and cystic fibrosis

INTRODUCTION

The 6-min walk test (6MWT) predicts outcome in pulmonary hypertension. Recently, its use was reported in both cystic fibrosis (CF) and bronchiolitis obliterans (BO). While the 6MWT is a simple, non-invasive and inexpensive tool, lung clearance index (LCI) measurement requires expensive equipment and expertise. We aimed to evaluate 6MWT in BO and CF, and to compare to MBW (multiple breath washout), pulmonary function tests and quality of life (QOL).

METHODS

A prospective single center study assessing 6MWT, MBW, spirometry, whole-body plethysmography and QOL (SF-36 questionnaire) in BO and CF patients and correlations between them.

RESULTS

Thirty-three BO patients and 37 CF patients. LCI was significantly higher in BO (12.4 ± 4.2 vs 10.5 ± 3.4, P = 0.044) while FEF 25-75% was significantly lower in BO (43.9 ± 24.4 vs 60.8 ± 30.8, P = 0.014). 6MWD was 474.8 ± 76.3 in BO and 506.6 ± 70 in CF (P > 0.05). There was no correlation between 6MWD and LCI in these small study groups There were few correlation between spirometry prameters and 6MWD. In CF, SF-36 scores correlated with pulmonary functions.

CONCLUSIONS

The 6MWT is an easy-to-perform test that may be helpful in chronic lung diseases in regions with limited resources. However,with the current limited data, 6MWT cannot replace LCI or spirometry as a marker of disease progression. Is is suggested that, together with QOL, the 6MWT may provide a global estimation of the physiological and general well-being of these patients. Further larger multi-center studies are warranted to evaluate the correlations of 6MWT with pulmonary physiology parameters in various chronic diseases.

Multiple breath washout in pediatric patients after lung transplantation

Forced expiratory volume in 1 second (FEV₁ ) from spirometry is the most commonly used parameter to detect early allograft dysfunction after lung transplantation (LTx). There are concerns regarding its sensitivity. Nitrogen-multiple breath washout (N₂ -MBW) is sensitive at detecting early global (lung clearance index [LCI]) and acinar (S_acin ) airway inhomogeneity. We investigated whether N₂ -MBW indices indicate small airways pathology after LTx in children with stable spirometry. Thirty-seven children without bronchiolitis obliterans syndrome [BOS] at a median of 1.6 (0.6-3.0) years after LTx underwent N₂ -MBW and spirometry, 28 of those on 2 occasions (≤6 months apart) during clinically stable periods. Additional longitudinal data (11 and 8 measurements, respectively) are provided from 2 patients with BOS. In patients without BOS, LCI and S_acin were significantly elevated compared with healthy controls. LCI was abnormal at the 2 test occasions in 81% and 71% of patients, respectively, compared with 30% and 39% of patients with abnormal FEV₁ /forced vital capacity (FVC). Correlations of LCI with FEV₁ /FVC (r = 0.1, P = .4) and FEV₁ (r = -0.1, P = .6) were poor. N₂ -MBW represents a sensitive and reproducible tool for the early detection of airways pathology in stable transplant recipients. Moreover, indices were highly elevated in both patients with BOS. Spirometry and LCI showed poor correlation, indicating distinct and complementary physiologic measures.