Exercise testing for children with cystic fibrosis: A systematic review

Comparison of the modified shuttle walk test in children with cystic fibrosis and healthy controls

OBJECTIVE

To evaluate and compare performance in the modified shuttle walk test (MSWT) with cardiorespiratory parameters and respiratory muscle strength in children with cystic fibrosis (CF) and healthy controls.

METHODS

A cross-sectional study with children divided into the CF group (CFG) and healthy control group (HCG). Two MSWTs were performed and the data from the test with the longest distance walked and its cardiorespiratory parameters (blood pressure, respiratory rate, heart rate (HR), oxygen saturation, and dyspnea sensation) were considered, the last three every 4 levels. Respiratory muscle strength was evaluated using a manometer. The Wilcoxon test was used to compare the parameters before and after the MSWT, and the Mann-Whitney and independent t-tests were applied to compare the data between the groups. The distance walked and its association with the variation in cardiorespiratory parameters and respiratory muscle strength were analyzed by Spearman's correlation.

RESULTS

Sixty-two children (31 in each group) participated, with an average age of 10.2 (2.1) years. Children with CF had poorer performance in the average distance walked (CFG 716.7 (274.3)) when compared to the HCG (948.0 (202.8)). Both groups exhibited an increase in all the cardiorespiratory parameters at the end of the test, but the CFG displayed less variation in some parameters. Children with CF presented a positive correlation between distance walked and respiratory muscle strength, HR variation, and systolic blood pressure.

CONCLUSIONS

There was no difference in respiratory muscle strength between the groups. In the CFG, the greater the respiratory muscle strength, the better the performance in the MSWT. The CFG exhibited less variation in cardiorespiratory parameters than the HCG.

Guidance and standard operating procedures for functional exercise testing in cystic fibrosis

Regular exercise testing is recommended for all people with cystic fibrosis (PwCF). A range of validated tests, which integrate both strength and aerobic function, are available and increasingly being used. Together, these tests offer the ability for comprehensive exercise evaluation. Extensive research and expert consensus over recent years has enabled the adaptation and standardisation of a range of exercise tests to aid the understanding of the pathophysiology related to exercise limitation in PwCF and has led to the development of novel exercise tests which may be applied to PwCF. This article provides expert, opinion-based clinical practice guidance, along with test instructions, for a selection of commonly used valid tests which have documented clinimetric properties for PwCF. Importantly, this document also highlights previously used tests that are no longer suggested for PwCF and areas where research is mandated. This collaboration, on behalf of the European Cystic Fibrosis Society Exercise Working Group, represents expert consensus by a multidisciplinary panel of physiotherapists, exercise scientists and clinicians and aims to improve global standardisation of functional exercise testing of PwCF. In short, the standardised use of a small selection of tests performed to a high standard is advocated.

Emerging Approaches to Monitor and Modify Care in the Era of Cystic Fibrosis Transmembrane Conductance Regulators

As we characterize the clinical benefits of highly effective modulator therapy (HEMT) in the cystic fibrosis (CF) population, our paradigm for treating and monitoring disease continues to evolve. More sensitive approaches are necessary to detect early disease and clinical progression. This article reviews evolving strategies to assess disease control and progression in the HEMT era. This article also explores developments in pulmonary function monitoring, advanced respiratory imaging, tools for the collection of patient-reported outcomes, and their application to profile individual responses, guide therapeutic decisions, and improve the quality of life of people with CF.

Cystic fibrosis year in review 2020: Section 2 pulmonary disease, infections, and inflammation

The outlook for those with cystic fibrosis (CF) has never been brighter with ever increasing life expectancy and the approval of the highly effective CFTR modulators, such as elexacaftor/tezacaftor/ivacaftor. With that being said, the progressive pulmonary decline and importance of lung health, infection, and inflammation in CF remains. This review is the second part in a three-part CF Year in Review 2020. Part one focused on the literature related to CFTR modulators while part three will feature the multisystem effects related to CF. This review focuses on articles from Pediatric Pulmonology, including articles from other journals that are of particular interest to clinicians. Herein, we highlight studies published during 2020 related to CF pulmonary disease, infection, treatment, and diagnostics.

The Fitter the Better? Cardiopulmonary Exercise Testing Can Predict Pulmonary Exacerbations in Cystic Fibrosis

Background: The role of cardiopulmonary exercise testing (CPET) in the assessment of prognosis in CF (cystic fibrosis) is crucial. However, as the overall survival of the disease becomes better, the need for examinations that can predict pulmonary exacerbations (PEx) and subsequent deterioration becomes evident. Methods: Data from a 10-year follow up with CPET and spirometry of CF patients were used to evaluate whether CPET-derived parameters can be used as prognostic indexes for pulmonary exacerbations in patients with CF. Pulmonary exacerbations were recorded. We used a survival analysis through Cox Regression to assess the prognostic role of CPET parameters for PeX. CPET parameters and other variables such as sputum culture, age, and spirometry measurements were tested via multivariate cox models. Results: During a 10-year period (2009–2019), 78 CF patients underwent CPET. Cox regression analysis revealed that VO₂peak% (peak Oxygen Uptake predicted %) predicted (hazard ratio (HR), 0.988 (0.975, 1.000) p = 0.042) and PetCO₂ (end-tidal CO₂ at peak exercise) (HR 0.948 (0.913, 0.984) p = 0.005), while VE/VO₂ and (respiratory equivalent for oxygen at peak exercise) (HR 1.032 (1.003, 1.062) p = 0.033) were significant predictors of pulmonary exacerbations in the short term after the CPET. Additionally, patients with VO₂peak% predicted <60% had 4.5-times higher relative risk of having a PEx than those with higher exercise capacity. Conclusions: CPET can provide valuable information regarding upcoming pulmonary exacerbation in CF. Patients with VO₂peak <60% are at great risk of subsequent deterioration. Regular follow up of CF patients with exercise testing can highlight their clinical image and direct therapeutic interventions.

Heart rate variability, exercise capacity and levels of daily physical activity in children and adolescents with mild-to-moderate cystic fibrosis

Background: Autonomic nervous system balance is altered in cystic fibrosis (CF), although its influence on physical fitness has been poorly explored.

Objective: This study aimed to evaluate the association of heart rate variability (HRV) with exercise capacity and levels of daily physical activity in children and adolescents with mild-to-moderate CF.

Methods: A cross-sectional study including individuals with CF aged 6–18 years, not under CFTR modulator therapy, was performed. Sociodemographic (age, sex) and clinical information (airway colonization, pancreatic insufficiency, and genotyping) were collected. In addition, exercise capacity (modified shuttle test — MST), lung function (spirometry), body composition (bioimpedance), levels of daily physical activity (5-day accelerometer), and HRV (both at rest and during the MST) were evaluated.

Results: 30 individuals (20 females) aged [Formula: see text] years, mean FEV[Formula: see text]%, were included. A sympathovagal balance (LF/HF) increase ([Formula: see text]) during the MST was shown, indicating a predominance of sympathetic modulation. The standard deviation of all RR intervals (SDNN) and the high frequency (HF) index during exercise correlated significantly with FEV1 ([Formula: see text], [Formula: see text] and [Formula: see text], [Formula: see text]; respectively). MST distance also correlated positively and significantly with SDNN ([Formula: see text], [Formula: see text]), square root of the mean of the sums of squares of frequencies between RR intervals greater than 50[Formula: see text]ms — RMSSD ([Formula: see text], [Formula: see text]), low frequency — LF ([Formula: see text], [Formula: see text]), HF ([Formula: see text], [Formula: see text]), dispersion of points perpendicular to the short-term identity line — SD1 ([Formula: see text], [Formula: see text]) and negatively with LF/HF ([Formula: see text], [Formula: see text]). Regarding daily physical activity, SDNN at rest ([Formula: see text], [Formula: see text]) and exercise ([Formula: see text], [Formula: see text]) showed positive correlations with time in moderate-to-vigorous activities. When normalizing the SDNN and classifying individuals as normal or altered, those presenting altered SDNN showed poorest FEV1 ([Formula: see text]) and lower exercise capacity ([Formula: see text]).

Conclusion: HRV correlates with lung function, exercise capacity and levels of daily physical activity in children and adolescents with CF. The study highlights the influence of CF on autonomic function and suggests HRV measurement as an easy tool to be used in clinical settings as an alternative marker to monitor CF individuals.

Clinical use of the modified shuttle test in children with cystic fibrosis: Is one test sufficient?

OBJECTIVE

To evaluate the reproducibility of the modified shuttle test (MST) and to determine whether the test needs to be performed more than once to assess the exercise capacity of children and adolescents with cystic fibrosis (CF).

METHODS

This was a longitudinal study including patients diagnosed with CF aged more than 6 years. The participants were followed for a period of 9 months and were evaluated at three different time points (visits 1, 2, and 3). Spirometric, anthropometric, clinical, and genetic data were collected, and two MSTs were performed at each visit.

RESULTS

Forty-eight clinically stable volunteers with a mean age of 10.1 ± 2.7 years were initially included. The reproducibility of the test was evaluated using the distance achieved (DA) as the main variable. There were no significant differences in the DA (visit 1, p = .23; visit 2, p = .24; visit 3, p = .85), baseline heart rate (HR) (visit 1, p = .35; visit 2, p = .20; visit 3, p = .98), and peak HR (visit 1, p = .16; visit 2, p = .94; visit 3, p = .23) between the tests performed at each visit. The test-retest reliability demonstrated a high intraclass correlation coefficient at all visits (visit 1, 2, and 3: 0.83, 0.90, and 0.80, respectively) and the variation in HR was the main factor associated with the DA in the MST over time.

CONCLUSION

The MST was found to be a reproducible and reliable test. The data presented here support the use of a single MST to evaluate and monitor exercise capacity of patients with CF during clinic visits.

Associations between peak oxygen uptake, lung function, and bronchiectasis in children with cystic fibrosis in the era of CFTR modulators

BACKGROUND

With the emergence of cystic fibrosis transmembrane conductance regulator (CFTR) modulators, forced expiratory volume in 1 s (FEV₁ ) may become a less sensitive measure of pulmonary disease progression in children with cystic fibrosis (CF). Increasing evidence shows that peak oxygen uptake (VO_2peak ) is a strong predictor of prognosis in CF. The primary aim of this study was to describe the associations between peak oxygen uptake, lung function, and bronchiectasis in children with CF in the era of CFTR modulators.

METHODS

Spirometry and a maximal cardiopulmonary exercise test (CPET) were performed on the same day and compared to markers of disease severity. Markers of disease severity included a number of pulmonary exacerbations resulting in hospital admission within the preceding 12 months, body mass index, Pseudomonas aeruginosa (PsA) infection, and bronchiectasis.

RESULTS

Fifty-two subjects (24 female) with CF participated in the study with a mean (SD) age of 13.8 (2.4) years, range 8-18 years. Forty-nine participants met satisfactory criteria for a maximal CPET. A significant correlation was found between relative VO_2peak %predicted and FEV₁ %predicted (r = .546, p < .001). A total of 4/49 children demonstrated an impaired aerobic capacity despite normal spirometry. Participants who had experienced one or more pulmonary exacerbations in the previous 12 months had a significantly lower relative VO_2peak %predicted (p = .02).

CONCLUSIONS

In children with CF who have mild pulmonary disease, there is significant correlation between FEV₁ and VO_2peak . In all, 8.2% of participants had an abnormal CPET result despite normal spirometry, and preceding pulmonary exacerbations were associated with poorer CPET outcomes. CPET may offer important prognostic information for clinical decision making in this new era of CFTR modulators.

Effect of expiratory muscle training on peak cough flow in children and adolescents with cystic fibrosis: A randomized controlled trial

BACKGROUND

Cough is an important defense and airway clearance mechanism for removing thick and viscous secretions in cystic fibrosis (CF). The primary aim of this study was to investigate the effect of expiratory muscle training (EMT) on peak cough flow (PCF) and secondly on respiratory muscle functions, functional exercise capacity, and quality of life (QoL) in CF.

METHODS

Thirty patients were randomized as training and sham groups. Both groups were trained with the EMT protocol, which involved twice per day for at least 5 days per week for 6 weeks. The training intensity in the training group was 30% of the maximal expiratory pressure (MEP). In the sham group, it remained at the lowest pressure (5 cmH₂ O). The primary outcome was PCF. The secondary outcomes were MEP, maximal inspiratory pressure (MIP), spirometric measures, six-minute walking distance (6MWD), and QoL (Cystic Fibrosis Questionnaire-Revised).

RESULTS

Twenty-eight patients completed the study. Changes in PCF (p = .041) and MEP (p = .003) were higher in the training group than the sham group. Also, treatment burden (p = .008), digestive symptoms (p = .019), and vitality (p = .042) in QoL were more improved in the training group. MIP (p = .028) and 6MWD (p = .035) changed significantly only in the training group. Spirometric measurements did not change (p > .05).

CONCLUSIONS

The results of the study show that EMT could improve PCF, MEP, treatment burden, digestive symptoms, and vitality domains of QoL in patients with CF. Moreover, MIP and functional exercise capacity improved in the training group with EMT.

Influence of sex-specific concurrent changes in age, maturity status, and morphological covariates on the development of peak ventilatory variables in 10-17-year-olds

Purposes

(i) To investigate the influence of concurrent changes in age, maturity status, stature, body mass, and skinfold thicknesses on the development of peak ventilatory variables in 10–17-year-olds; and, (ii) to evaluate the interpretation of paediatric norm tables of peak ventilatory variables.

Methods

Multiplicative multilevel modelling which allows both the number of observations per individual and the temporal spacing of the observations to vary was used to analyze the expired ventilation (peak \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\mathrm{V}}}_{\mathrm{E}}$$\end{document}V˙E) and tidal volume (peak V_T) at peak oxygen uptake of 420 (217 boys) 10–17-year-olds. Models were founded on 1053 (550 from boys) determinations of peak ventilatory variables supported by anthropometric measures and maturity status.

Results

In sex-specific, multiplicative allometric models, concurrent changes in body mass and skinfold thicknesses (as a surrogate of FFM) and age were significant (p < 0.05) explanatory variables of the development of peak \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\mathrm{V}}}_{\mathrm{E}}$$\end{document}V˙E, once these covariates had been controlled for stature had no additional, significant (p > 0.05) effect on peak \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\mathrm{V}}}_{\mathrm{E}}$$\end{document}V˙E. Concurrent changes in age, stature, body mass, and skinfold thicknesses were significant (p < 0.05) explanatory variables of the development of peak V_T. Maturity status had no additional, significant (p > 0.05) effect on either peak \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\mathrm{V}}}_{\mathrm{E}}$$\end{document}V˙E or peak V_T once age and morphological covariates had been controlled for.

Conclusions

Elucidation of the sex-specific development of peak \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\mathrm{V}}}_{\mathrm{E}}$$\end{document}V˙E requires studies which address concurrent changes in body mass, skinfold thicknesses, and age. Stature is an additional explanatory variable in the development of peak V_T, in both sexes. Paediatric norms based solely on age or stature or body mass are untenable.