Exercise intolerance, oxidative stress, and irisin in pediatric cystic fibrosis: Can telehealth-based exercise training make a difference?

BACKGROUND

Patients with cystic fibrosis (CF) experience increased oxidative stress. Tele-exercise can be a new method to improve exercise in CF.

OBJECTIVE

This study aimed to investigate the effect of telehealth-based exercise training using different modalities (combined exercise training group, CombG, core stabilization exercise group, SG), in comparison with control group (CG), on exercise capacity, oxidative stress, and irisin in children with CF.

METHODS

Thirty-nine children with CF (mean age=11.41±2.18 years, mean FEV1(z-score)=-0.66±1.96) were included in the study. The children were randomly allocated to groups. The CombG and SG performed core stabilization exercises (CS) 3 days per week for 8 weeks. The CombG also performed aerobic exercises 3 days per week in addition to CS. Physical activity (PA) recommendations were provided to the CG. Exercise capacity was evaluated using the Modified Shuttle Test (MST). Oxidative stress was assessed using total antioxidant status (TAS), total oxidant status (TOS), Oxidative Stress Index (OSI), malondialdehyde (MDA), and superoxide dismutase (SOD). The irisin level was also measured.

RESULTS

Children's baseline sex, age, BMI, and FEV1 z-scores were similar (p > 0.05). The MST distance (p = 0.047,np2=0.157) and%MST distance (p = 0.045, np2=0.159) significantly improved in the CombG compared with the SG and CG. Although TAS and SOD decreased over time (p < 0.05), no significant changes were observed for TAS, TOS, OSI, MDA, SOD, and irisin parameters between the groups after training (p > 0.05).

CONCLUSIONS

Combining aerobic exercise training with core stabilization applied using telehealth improved exercise capacity more than core stabilitation training only or PA recommendations in children with CF.

Percentage Predicted Peak Oxygen Consumption in People With Fontan Circulation: A Rapid Systematic Scoping Review and Validation Study

BACKGROUND

Peak oxygen consumption (peak V ̇ O 2 $$ \dot{\mathrm{V}}{\mathrm{O}}_2 $$ ) is routinely measured in people who have congenital heart disease and is reported as a percentage of predicted value, based upon age- and sex-matched normative reference values (NRVs). This study aimed to identify which NRVs are being used, assess whether NRVs are being applied appropriately, and evaluate if recommended NRVs are valid when applied to people with congenital heart disease.

METHODS AND RESULTS

A systematic scoping review identified studies that reported peak V ̇ O 2 $$ \dot{\mathrm{V}}{\mathrm{O}}_2 $$ percentage of predicted value in people with congenital heart disease. A modified risk of bias tool evaluated the included studies. Forty-five studies reported peak V ̇ O 2 $$ \dot{\mathrm{V}}{\mathrm{O}}_2 $$ percentage of predicted value, and only 21 (47%) studies described or provided a reference on how their percentage of predicted value was calculated. The most cited NRVs were from Wasserman (n=12) and Cooper and Weiler-Ravell (n=7). Risk of bias analysis judged 63% of studies as having some concerns. The NRVs recommended by the American Heart Association were applied to participants with a Fontan circulation (n=70; aged 26.5±6.4 years; 59% women) to examine validity. Predicted peak V ̇ O 2 $$ \dot{\mathrm{V}}{\mathrm{O}}_2 $$ values from the Wasserman NRV was not significantly associated to measured peak V ̇ O 2 $$ \dot{\mathrm{V}}{\mathrm{O}}_2 $$ values (men: b=0.31, R2≤0.01; women: b=0.07, R2=0.02).

CONCLUSIONS

Numerous NRVs have been applied to individuals with congenital heart disease and are often poorly reported and inappropriately matched to participants. The Wasserman NRV was the most cited but showed poor validity when applied to a Fontan cohort.

Practical Aspects of Cardiopulmonary Exercise Testing in Children

The use of cardiopulmonary exercise testing (CPET) in pediatrics provides critical insights into potential physiological causes of unexplained exercise-related complaints or symptoms, as well as specific pathophysiological patterns based on physiological responses or abnormalities. Furthermore, CPET helps evaluate exercise performance in children with chronic (lung/heart) diseases. For instance, it can ascertain any adverse reaction to exercise and estimate the effects of specific treatment measures. It affords a global assessment of the pathophysiological patterns, responses and abnormalities to exercise that is inadequately reflected by resting lung function and/or cardiac function assessment. Clinical interpretation of the results of a CPET in pediatrics requires specific knowledge regarding pathophysiological responses and interpretative strategies that can be adapted to address concerns specific to the child's medical condition or disability.

Changes in exercise capacity in people with Cystic Fibrosis after one year of Elexacaftor/Tezacaftor/Ivacaftor treatment - A Danish prospective cohort

BACKGROUND

Cystic Fibrosis (CF) is an inherited multiorgan disease that causes lung damage and early death. People with CF (pwCF) experience diminished exercise capacity compared to the general population. This is due to an accelerated decline in lung function resulting from recurrent lung infections, declining lung function and nutritional challenges. Since 2020 the CFTR-modulator Elexacaftor/Tezacaftor/Ivacaftor (ETI) has been approved for pwCF aged 12 and above in Denmark. Initial experiences with the medication have shown promising results, including improved lung function and disease stability. To date a limited number of studies have evaluated the impact of CFTR-modulators on exercise capacity in pwCF.

OBJECTIVE

The study aims to assess the impact of one year of ETI treatment, without any further intervention, on exercise capacity measured through cardiopulmonary exercise test (CPET) in pwCF aged 12 years and above.

METHODS

A Danish prospective registry cohort study including pwCF from CF-Center Copenhagen, Copenhagen University Hospital and CF-Center Aarhus, Aarhus University Hospital. Participants underwent CPET before initiating ETI and at follow up one year later. Primary outcomes were VO₂ peak (ml/kg/min), secondary outcomes were VO2 peak (ml/min), VO2 peak (% pred), watt-max, HR-max and saturation at max. The difference between baseline and follow-up was assessed using a paired-sample t-test and regression analyses were applied to relevant outcomes.

RESULTS

We included 229 pwCF in the analyses. An increase in oxygen uptake, VO₂ peak (ml/kg/min) from baseline to follow-up was observed; 0.6, 95% CI [0.06; 1.09] p = 0.03. Moreover, significant increase was noted for all other CPET outcomes. Regression analysis showed that changes in FEV₁% pred and BMI could explain some of the differences, 0.05 ml/kg/min, 95% CI [0.01, 0.1] p = 0.02 and -0.5 ml/kg/min, 95% CI [-0.8, -0.2] p = 0.002 respectively.

CONCLUSION

Among Danish pwCF we found a significant, but not clinically relevant, increase in oxygen uptake, after one year of ETI treatment.

Using reference equations to standardise incremental shuttle walk test performance in children and young people with chronic conditions and facilitate the evaluation of exercise capacity and disease severity

AIMS

The aim was to evaluate whether standardised exercise performance during the incremental shuttle walk test (ISWT) can be used to assess disease severity in children and young people (CYP) with chronic conditions, through (1) identifying the most appropriate paediatric normative reference equation for the ISWT, (2) assessing how well CYP with haemophilia and cystic fibrosis (CF) perform against the values predicted by the best fit reference equation and (3) evaluating the association between standardised ISWT performance and disease severity.

METHODS

A cross-sectional analysis was carried out using existing data from two independent studies (2018-2019) at paediatric hospitals in London,UK. CYP with haemophilia (n=35) and CF (n=134) aged 5-18 years were included. Published reference equations for standardising ISWT were evaluated through a comparison of populations, and Bland-Altman analysis was used to assess the level of agreement between distances predicted by each equation. Associations between ISWT and disease severity were assessed with linear regression.

RESULTS

Three relevant reference equations were identified for the ISWT that standardised performance based on age, sex and body mass index (Vardhan, Lanza, Pinho). A systematic proportional bias of standardised ISWT was observed in all equations, most pronounced with Vardhan and Lanza; the male Pinho equation was identified as most appropriate. On average, CYP with CF and haemophilia performed worse than predicted by the Pihno equation, although the range was wide. Standardised ISWT, and not ISWT distance alone, was significantly associated with forced expiratory volume in 1 s in CYP with CF. Standardised ISWT in CYP with haemophilia was slightly associated with haemophilia joint health score, but this was not significant.

CONCLUSIONS

ISWT performance may be useful in a clinic to identify those with worsening disease, but only when performance is standardised against a healthy reference population. The development of validated global reference equations is necessary for more robust assessment.

Exercise performance in children and adolescents with cystic fibrosis with and without abnormal glucose tolerance: a single center cross-sectional study

BACKGROUND

Abnormal glucose tolerance (AGT) in cystic fibrosis (CF) affects lung function and clinical parameters, including aerobic fitness. However, its effects on physical activity level (PAL), anaerobic power (AP), and muscle strength (MS) in children and adolescents are unknown.

PURPOSE

To investigate aerobic fitness, PAL, AP, and MS in pediatric patients with mild-to-moderate CF and AGT.

METHODS

The study included children and adolescents with CF aged 10-18 years. Participants underwent a pulmonary function test, quadriceps, and handgrip MS measurement, vertical jump test to assess AP, and six-minute walk test (6MWT) to assess aerobic fitness. Bouchard's Three-Day Physical Activity record was used to determine PAL.

RESULTS

Height z-score (p = .006), 6MWT (p = .024), handgrip (p = .028), quadriceps MS (p = .044), and AP (p = .036) were significantly lower in AGT (n = 21) than normal glucose tolerance (NGT) (n = 19). In the AGT group, glycosylated hemoglobin (HbA1c) was significantly associated with forced expiratory volume in one second (FEV1) (p = .046). 6MWT distance (6MWD) was associated with height (p = .008), FEV1 (p = .001), forced vital capacity (FVC) (p = .001), forced expiratory flow from 25% to 75% (FEF25-75%) (p = .030), handgrip MS (p = .012), and PAL (p = .034). After adjusting for height and FEV1, the groups had similar 6MWD, MS, and AP (p > .05); also, insulin was associated with MS and AP but not with 6MWT or quadriceps MS.

CONCLUSION

Measures of aerobic fitness, MS, and AP are lower in AGT, but after adjusting for height and FEV1, aerobic fitness, MS, and AP do not show substantial differences. Insulin sensitivity and resistance are associated with MS and AP.

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.

Standards for the care of people with cystic fibrosis; establishing and maintaining health

This is the second in a series of four papers updating the European Cystic Fibrosis Society (ECFS) standards for the care of people with CF. This paper focuses on establishing and maintaining health. The guidance is produced using an evidence-based framework and with wide stakeholder engagement, including people from the CF community. Authors provided a narrative description of their topic and statements, which were more directive. These statements were reviewed by a Delphi exercise, achieving good levels of agreement from a wide group for all statements. This guidance reinforces the importance of a multi-disciplinary CF team, but also describes developing models of care including virtual consultations. The framework for health is reinforced, including the need for a physically active lifestyle and the strict avoidance of all recreational inhalations, including e-cigarettes. Progress with cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy is reviewed, including emerging adverse events and advice for dose reduction and interruption. This paper contains guidance that is pertinent to all people with CF regardless of age and eligibility for and access to modulator therapy.

Impact of CFTR modulators on exercise capacity in adolescents with cystic fibrosis

Background

Exercise capacity is an independent predictor of clinical worsening in cystic fibrosis (CF). There is limited evidence of the impact of cystic fibrosis transmembrane conductance regulator (CFTR) modulators on exercise capacity in children with CF. The aim of the present study was to assess the impact of CFTR modulators on exercise capacity in a cohort of adolescents with CF.

Methods

A prospective single-centre cohort study was carried out. Cardiopulmonary exercise testing (CPET) was performed at baseline, prior to starting Symkevi or Kaftrio and between 4 and 8 months after starting treatment.

Results

19 adolescents with CF had CPET performed prior to and after CFTR modulator treatment, between December 2019 and March 2022. Breathing reserve improved in the whole cohort, with greater improvement in the modulator-naïve patients after starting treatment with Kaftrio. There was no improvement in peak oxygen uptake and anaerobic threshold after 4 to 8 months of treatment with CFTR modulators.

Conclusion

Exercise testing with CPET can be used as an additional tool to monitor response to CFTR modulators. Breathing reserve on CPET may provide a surrogate marker to monitor the improvement in CF lung disease with CFTR modulator treatment.

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.

Dynamic Hyperinflation While Exercising-A Potential Predictor of Pulmonary Deterioration in Cystic Fibrosis

BACKGROUND

Lung function deterioration in cystic fibrosis (CF) is typically measured by a decline in the forced expiratory volume in one second (FEV1%), which is thought to be a late marker of lung disease. Dynamic hyperinflation (DH) is seen in obstructive lung diseases while exercising. Our aim was to assess whether DH could predict pulmonary deterioration in CF; a secondary measure was the peak VO2.

METHODS

A retrospective study was conducted of people with CF who performed cardiopulmonary exercise tests (CPETs) during 2012-2018. The tests were classified as those demonstrating DH non-DH. Demographic, genetic, and clinical data until 12.2022 were extracted from patient charts.

RESULTS

A total of 33 patients aged 10-61 years performed 41 valid CPETs with valid DH measurements; sixteen (39%) demonstrated DH. At the time of the CPETs, there was no difference in the FEV1% measurements between the DH and non-DH groups (median 83.5% vs. 87.6%, respectively; p = 0.174). The FEV1% trend over 4 years showed a decline in the DH group compared to the non-DH group (p = 0.009). A correlation was found between DH and the lung clearance index (LCI), as well as the FEV1% (r = 0.36 and p = 0.019 and r = -0.55 and p = 0.004, respectively). Intravenous (IV) antibiotic courses during the 4 years after the CPETs were significantly more frequent in the DH group (p = 0.046). The peak VO2 also correlated with the FEV1% and LCI (r = 0.36 and p = 0.02 and r = -0.46 and p = 0.014, respectively) as well as with the IV antibiotic courses (r = -0.46 and p = 0.014).

CONCLUSIONS

In our cohort, the DH and peak VO2 were both associated with lung function deterioration and more frequent pulmonary exacerbations. DH may serve as a marker to predict pulmonary deterioration in people with CF.

Survey of exercise testing and training in cystic fibrosis clinics in the UK: a decade of progress

OBJECTIVES

Regular exercise testing is recommended for people with cystic fibrosis (pwCF), as is the provision and regular review of exercise training programmes. A previous survey on exercise testing and training for pwCF in the UK was conducted over a decade ago. With the landscape of CF changing considerably during this time, this survey aimed to evaluate UK-based exercise testing and training practices for pwCF a decade on.

DESIGN

Cross-sectional, online survey.

PARTICIPANTS

A survey was distributed electronically to UK CF clinics and completed by the individual primarily responsible for exercise services. Descriptive statistics and qualitative analyses were undertaken.

RESULTS

In total, 31 CF centres participated, representing ~50% of UK specialist clinics. Of these, 94% reported using exercise testing, 48% of which primarily use cardiopulmonary exercise testing. Exercise testing mostly occurs at annual review (93%) and is most often conducted by physiotherapists (62%). A wide variation in protocols, exercise modalities, normative reference values and cut-offs for exercise-induced desaturation are currently used. All centres reportedly discuss exercise training with pwCF; 94% at every clinic appointment. However, only 52% of centres reportedly use exercise testing to inform individualised exercise training. Physiotherapists typically lead discussions around exercise training (74%).

CONCLUSIONS

These data demonstrate that the majority of respondent centres in the UK now offer some exercise testing and training advice for pwCF, representing a marked improvement over the past decade. However, continued efforts are now needed to standardise exercise practices, particularly regarding field testing practices and the translation of test results into personalised training programmes for pwCF.

Exercise and Airway Clearance Techniques in Cystic Fibrosis

Exercise and airway clearance techniques (ACTs) have been a cornerstone of treatment for people with cystic fibrosis (pwCF) for many decades. Exercise may confer both respiratory and nonrespiratory benefits for pwCF, with greater exercise capacity associated with improved survival. A wide variety of exercise interventions for pwCF have been investigated. ACTs may assist in reducing respiratory symptoms for pwCF and are currently recommended to be performed daily, with the types of ACTs used varying globally. While recommended components of care, both exercise and ACTs are time-intensive and maintaining adherence to the recommendations over the longer term can be challenging. It has been proposed that with advances in the therapeutic options for pwCF, a rationalization of the therapeutic regimen may be possible. We summarize the current evidence for the use of exercise and ACTs by pwCF, discuss the implications of the introduction of cystic fibrosis transmembrane conductance regulator modulators on both exercise and ACTs, and highlight areas for further research.

Systematic review and meta-analysis: Associations of vitamin D with pulmonary function in children and young people with cystic fibrosis

BACKGROUND

Increasing evidence suggests that vitamin D is associated with pulmonary health, which may benefit children and young people diagnosed with Cystic Fibrosis (cypCF). Therefore, the aim of this systematic review was to evaluate primary research to establish associations between 25OHD and pulmonary health in cypCF.

METHODS

Electronic databases were searched with keywords related to CF, vitamin D, children/young people and pulmonary function. Included studies were cypCF (aged ≤21 years) treated in a paediatric setting. The primary outcome was lung function [forced expiratory volume in 1 s (FEV₁% predicted)] and secondary outcomes were rate of pulmonary exacerbations, 25OHD status and growth. Evidence was appraised for risk of bias using the CASP tool, and quality using the EPHPP tool. A Meta-analysis was performed.

RESULTS

Twenty-one studies were included with mixed quality ratings and heterogeneity of reported outcomes. The Meta-analysis including 5 studies showed a significantly higher FEV₁% predicted in the 25OHD sufficiency compared to the deficiency group [FEV₁% predicted mean difference (95% CI) was 7.71 (1.69-13.74) %; p = 0.01]. The mean ± SD FEV₁% predicted for the sufficient (≥75 nmol/L) vs. deficient (<50 nmol/L) group was 94.7 ± 31.9% vs. 86.9 ± 13.2%; I² = 0%; χ² = 0.5; df = 4). Five studies (5/21) found significantly higher rate of pulmonary exacerbations in those who were 25OHD deficient when compared to the sufficient group and negative associations between 25OHD and FEV% predicted. The effects of vitamin D supplementation dosages on 25OHD status (10/21) varied across studies and no study (12/21) showed associations between 25OHD concentration and growth.

CONCLUSION

This systematic review suggests that 25OHD concentration is positively associated with lung function and a concentration of >75 nmol/L is associated with reduced frequency of pulmonary exacerbations, which may slow lung function decline in cypCF. Future randomised clinical trials and mechanistic studies are warranted.

Normal reference values for aerobic fitness in cystic fibrosis: a scoping review

Objective

The importance of aerobic fitness (VO2peak) in cystic fibrosis (CF) is well established, and regular exercise testing is recommended. To standardise VO2peak, a ‘percentage of predicted’ (%pred) derived from normative reference values (NRV), as promoted by the 2015 European Cystic Fibrosis Society Exercise Working Group (ECFS EWG), can be reported. However, the NRVs used in CF and their relative frequency is unknown.

Method

A scoping review was performed via systematic database searches (PubMed, Embase, Web of Science, SciELO, EBSCO) and forward citation searches for studies that include people with CF and report VO2peakas %pred. Studies were screened using Covidence, and data related to patient demographics, testing modality and reference equations were extracted. Additional analyses were performed on studies published in 2016–2021, following the ECFS EWG statement in 2015.

Results

A total of 170 studies were identified, dating from 1984 to 2022, representing 6831 patients with CF, citing 34 NRV. Most studies (154/170) used cycle ergometry, 15/170 used treadmills, and the remainder used alternative, combination or undeclared modalities. In total, 61/170 failed to declare the NRV used. There were 61 studies published since the ECFS EWG statement, whereby 18/61 used the suggested NRV.

Conclusion

There is a wide discrepancy in NRV used in the CF literature base to describe VO2peakas %pred, with few studies using NRV from the ECFS EWG statement. This high variance compromises the interpretation and comparison of studies while leaving them susceptible to misinterpretation and limiting replication. Standardisation and alignment of reporting of VO2peakvalues are urgently needed.

Feasibility of the A-STEP for the assessment of exercise capacity in people with cystic fibrosis

OBJECTIVES

To evaluate feasibility of the Alfred Step Test Exercise Protocol (A-STEP) for the assessment of exercise capacity in adults and children with cystic fibrosis (CF); in adults to test whether demographics and/or lung function correlated with exercise capacity.

METHODS

Adults and children with stable CF from two centres completed the A-STEP (a recently developed incremental maximal-effort step test). Feasibility was evaluated by: usefulness for exercise capacity assessment (measures of exercise capacity were: level reached, exercise-induced desaturation, and achievement of at least one maximal effort criteria); safety; operational factors; time to complete; floor and/or ceiling effects. We used multiple linear regression to test whether demographics and/or lung function correlated with exercise capacity.

RESULTS

A total of 49 participants: 38 adults (18 male), percent predicted (pp) forced expiration in one second (FEV₁ ) 29-109, aged 22-48 years and 11 children (6 male), ppFEV₁ 68-107, aged 10-15 years were included. Levels reached (mean (SD) [range]) were 10.2 (2.4) [6-15] (adults), 10.1 (2.5) [7-14] (children); desaturation (change between baseline and peak-exercise SpO₂ ): was 8.4 (3.8 [0-15]% (adults), 2.0 (2.0) [0-7]% (children). A total of 8 (21%) adults and no children desaturated <90% SpO₂ . At least one criterion for maximal effort was reached by 33 (84%) adults and 10 (91%) children. There were no adverse events. The A-STEP was straightforward to use and carried out by one operator. A total of 26 (68.4%) adults and 7 (63.6%) children completed the test within the recommended 8-12 min. All participants completed a minimum of 6 levels, and completed the test before the final 16th level. In adults, ppFEV₁ and ppFVC correlated with the level reached (r = 0.55; p = <0.001 and r = 0.66, p = <0.0001) and desaturation (r = 0.55, p = <0.001 and r = 0.45, p = <0.005).

CONCLUSION

In adults and children with stable CF, the A-STEP was feasible, safe, and operationally easy to use for the assessment of exercise capacity, without floor or ceiling effects. In adults, lung function correlated with exercise capacity.

Limitations of the dichotomized 6-minute walk distance when computing lung allocation score for cystic fibrosis: a 16-year retrospective cohort study

PURPOSE

The 2010 Lung Allocation Score (LAS) version considers the estimated survival benefit offered by lung transplantation (LTx) and uses 6-minute Walk Test (6MWT) distance as a dichotomous covariate of whether an individual can walk more than 150 ft or 45.7 m in 6 min. This study aimed to provide evidence that 6MWT gives no clinically meaningful information to be used in the current LAS for candidates to LTx with cystic fibrosis (CF).

MATERIALS AND METHODS

We collected data from 6MWTs performed since 2003 at our CF centre. A joint model was fitted to describe the effect of changes in walked distance on the hazard of LTx or death.

RESULTS

Up to 2019, 552 6MWTs were performed on 163 individuals with CF. None of the individuals included walked for less than 45.7 m during the 6MWT. Based on the joint modelling, the association of walked distance with the hazard ratio (HR) of LTx or death was significant (HR 0.99, 95% Credible Interval [CI]: 0.99 to 1.00).

CONCLUSIONS

When adopted dichotomously for LAS calculation, walked distance does not add any useful information about exercise capacity. Longitudinal trajectories of walked distance may provide complementary information about prognosis in individuals with CF.Implications for rehabilitationDichotomized walked distance does not contribute to lung allocation score in candidates to lung transplantation with cystic fibrosisChanges in the longitudinal trajectory of walked distance can be clinically meaningful for prognostication.Sensitive outcomes to be incorporated in the lung allocation scoring system for individuals with CF are yet needed to catch rapid falls in functional capacity.

Effects of a Long-Term Monitored Exercise Program on Aerobic Fitness in a Small Group of Children with Cystic Fibrosis

Background: The aim of this study was to investigate the effects of a monitored exercise program on aerobic fitness in children with cystic fibrosis (CF). Methods: Six children (2f/4m) with ages ranging from 6 to 14 years (11.3 ± 3.3 years.) and a mean ppFEV1 102.5 ± 13.5% pred. participated in the partially monitored 12-month exercise program. VO2peak and Wpeak were used as parameters of aerobic fitness. Incremental Cardio-Pulmonary Exercise Tests (CPETs) were performed before the program began (T1), after 6 months (T3) of monitoring, and after a further 6 months (T4) without monitoring. Habitual physical activity (HPA) was assessed with accelerometry. Results: The values of VO2peak and Wpeak improved slightly from T1 to T3 (p > 0.05), without a further increase after monitoring was stopped (T4). However, the VO2peak and Wpeak values were higher after monitoring was stopped compared to at T1. The exercise program with and without monitoring (p > 0.05) had no or only a slight effect on the FEV1 values, steps/day, and the intensity of HPA. Conclusions: Monitoring seems to facilitate the achievement of beneficial effects on physical fitness in CF children. For that reason, continuous individual exercise monitoring programs that involve close contact with an exercise therapist should be provided to maintain long-term motivation and participation in physical activities and sport activities during leisure time.

Exercise versus airway clearance techniques for people with cystic fibrosis

BACKGROUND

There are many accepted airway clearance techniques (ACTs) for managing the respiratory health of people with cystic fibrosis (CF); none of which demonstrate superiority. Other Cochrane Reviews have reported short-term effects related to mucus transport, but no evidence supporting long-term benefits. Exercise is an alternative ACT thought to produce shearing forces within the lung parenchyma, which enhances mucociliary clearance and the removal of viscous secretions. Recent evidence suggests that some people with CF are using exercise as a substitute for traditional ACTs, yet there is no agreed recommendation for this. Additionally, one of the top 10 research questions identified by people with CF is whether exercise can replace other ACTs. Systematically reviewing the evidence for exercise as a safe and effective ACT will help people with CF decide whether to incorporate this strategy into their treatment plans and potentially reduce their treatment burden. The timing of this review is especially pertinent given the shifting landscape of CF management with the advent of highly-effective small molecule therapies, which are changing the way people with CF are cared for.

OBJECTIVES

To compare the effect of exercise to other ACTs for improving respiratory function and other clinical outcomes in people with CF and to assess the potential adverse effects associated with this ACT.

SEARCH METHODS

On 28 February 2022, we searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles and reviews. We searched online clinical trial registries on 15 February 2022. We emailed authors of studies awaiting classification or potentially eligible abstracts for additional information on 1 February 2021.

SELECTION CRITERIA

We selected randomised controlled studies (RCTs) and quasi-RCTs comparing exercise to another ACT in people with CF for at least two treatment sessions.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed risk of bias for the included studies. They assessed the certainty of the evidence using GRADE. Review authors contacted investigators for further relevant information regarding their publications.

MAIN RESULTS

We included four RCTs. The 86 participants had a wide range of disease severity (forced expiratory volume in one second (FEV1) ranged from 54% to 95%) and were 7 to 41 years old. Two RCTs were cross-over and two were parallel in design. Participants in one RCT were hospitalised with an acute respiratory exacerbation, whilst the participants in three RCTs were clinically stable. All four RCTs compared exercise either alone or in combination with another ACT, but these were too diverse to allow us to combine results. The certainty of the evidence was very low; we downgraded it due to low participant numbers and high or unclear risks of bias across all domains. Exercise versus active cycle of breathing technique (ACBT) One cross-over trial (18 participants) compared exercise alone to ACBT. There was no change from baseline in our primary outcome FEV1, although it increased in the exercise group before returning to baseline after 30 minutes; we are unsure if exercise affected FEV1 as the evidence is very low-certainty. Similar results were seen for other measures of lung function. No adverse events occurred during the exercise sessions (very low-certainty evidence). We are unsure if ACBT was perceived to be more effective or was the preferred ACT (very low-certainty evidence). 24-hour sputum volume was less in the exercise group than with ACBT (secondary outcome). Exercise capacity, quality of life, adherence, hospitalisations and need for additional antibiotics were not reported. Exercise plus postural drainage and percussion (PD&P) versus PD&P only Two trials (55 participants) compared exercise and PD&P to PD&P alone. At two weeks, one trial narratively reported a greater increase in FEV1 % predicted with PD&P alone. At six months, the other trial reported a greater increase with exercise combined with PD&P, but did not provide data for the PD&P group. We are uncertain whether exercise with PD&P improves FEV1 as the certainty of evidence is very low. Other measures of lung function did not show clear evidence of effect. One trial reported no difference in exercise capacity (maximal work rate) after two weeks. No adverse events were reported (1 trial, 17 participants; very low-certainty evidence). Adherence was high, with all PD&P sessions and 96% of exercise sessions completed (1 trial, 17 participants; very low-certainty evidence). There was no difference between groups in 24-hour sputum volume or in the mean duration of hospitalisation, although the six-month trial reported fewer hospitalisations due to exacerbations in the exercise and PD&P group. Quality of life, ACT preference and need for antibiotics were not reported. Exercise versus underwater positive expiratory pressure (uPEP) One trial (13 participants) compared exercise to uPEP (also known as bubble PEP). No adverse events were recorded in either group (very low-certainty evidence). Trial investigators reported that participants perceived exercise as more fatiguing but also more enjoyable than bubble PEP (very low-certainty evidence). There were no differences found in the total weight of sputum collected during treatment sessions. The trial did not report the primary outcomes (FEV1, quality of life, exercise capacity) or the secondary outcomes (other measures of lung function, adherence, need for antibiotics or hospitalisations).

AUTHORS' CONCLUSIONS

As one of the top 10 research questions identified by clinicians and people with CF, it is important to systematically review the literature regarding whether or not exercise is an acceptable and effective ACT, and whether it can replace traditional methods. We identified an insufficient number of trials to conclude whether or not exercise is a suitable alternative ACT, and the diverse design of included trials did not allow for meta-analysis of results. The evidence is very low-certainty, so we are uncertain about the effectiveness of exercise as an ACT. Longer studies examining outcomes that are important to people with CF are required to answer this question.

Change in exercise capacity measured by Cardio-pulmonary Exercise Testing (CPET) in Danish people with cystic fibrosis after initiation of treatment with Lumacaftor/Ivacaftor and Tezacaftor/Ivacaftor

BACKGROUND

Since 2015, when the first cystic fibrosis transmembrane conductance regulator (CFTR) modulators were approved for people with cystic fibrosis (CF) homozygous for F508del-CFTR, studies have shown improved lung function after initiation of the treatment and patients experience improved physical capacity. The aim of this study was to investigate change in exercise capacity after initiation of Lumacaftor/Ivacaftor and Tezacaftor/Ivacaftor treatment (LUM/IVA, TEZ/IVA).

METHODS

We performed a single group prospective observational cohort study with follow-up at six and 12 months. The study examined change in exercise capacity in people with CF initiating treatment with LUM/IVA and TEZ/IVA, measured by cardio-pulmonary exercise testing (CPET). Inclusion criteria were people with CF homozygous for F508del-CFTR aged 12 years or older eligible for LUM/IVA and TEZ/IVA treatment from June 2017 until June 2019. Primary outcomes were change in VO_2peak and maximal workload. Secondary outcomes were change in muscle strength, muscle power and body composition in a subgroup of the study population.

RESULTS

A total of 91 patients were included in the analysis. The mean change in VO_2peak and VO_2peak divided by body weight from baseline to 12-months follow-up was 145.7 (91.2;200.2) ml/min and 1.07 (95% CI 0.19;1.95) ml/min/kg, respectively. The mean change in maximal workload between baseline and 12 months was 14.2 Watt (95% CI 9.1;19.2). All improvements in exercise capacity were statistically significant.

CONCLUSIONS

Patients in this study improved their exercise capacity by a statistically significant increase in VO_2peak and maximal workload 12 months after initiation of treatment with LUM/IVA and TEZ/IVA.

Association between Cardiopulmonary Capacity and Body Mass Composition in Children and Adolescents with High Body Weight: A Cross-Sectional Study

(1) Background: Excessive body weight is a global problem in the 21st century. Children and adolescents, in particular, are at risk. Recently, there has been an increasing interest in the relationship between aerobic capacity and body composition. Therefore, this study aimed to determine the association between the individual parameters of cardiopulmonary capacity obtained in cardiopulmonary exercise testing (CPET) and selected parameters of body mass composition in high-BMI children and children over the 85th percentile according to the WHO growth reference. (2) Materials and Method: The research included 100 children of school-age (7-15 years) with an excessive BMI, i.e., over the 85th percentile as per the WHO Growth Reference (BMI percentile 95.21 ± 4.65; Z-score BMI: 2.07 ± 0.94). The study consisted of three parts: anthropometric measurements, measurement of body mass composition using a body composition analyzer (TANITA MC-780 S MA) using the bioimpedance method, and a cardiopulmonary exercise test on a pediatric cycle ergometer (Corival Pediatric, Lode BV) using the Godfrey protocol; (3) Results: The correlation between BMI and fat mass (FM) was very high (rho = 0.83; p = 0.00) with moderate body fat percentage (BF%) (rho = 0.48; p = 0.00). There was a relevant correlation between the amount of fat-free mass in total body mass and cardiopulmonary capacity expressed as the absolute aerobic capacity (VO2peak) (rho = 0.55; p = 0.00). (4) Conclusions: In the case of children and youth with higher BMI, there was a correlation between the amount of fat-free mass in total body mass and cardiopulmonary capacity in terms of absolute aerobic capacity.

The Effect of Dysglycaemia on Changes in Pulmonary and Aerobic Function in Cystic Fibrosis

Cross-sectional studies have reported lower pulmonary and aerobic function during exercise in people with cystic fibrosis-related diabetes (CFRD) compared to non-CFRD counterparts. However, this association has yet to be longitudinally investigated. Therefore, this study examines these differences over time between people with cystic fibrosis (CF) of differing glycaemic status. Annual review data, including cardiopulmonary exercise tests and pulmonary function tests, were retrospectively analysed at baseline (T0, n = 82) and at a one-year follow-up (T1, n = 54). Data was analysed in three groups: normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and CFRD. Further analyses were undertaken, with a dichotomous split of NGT and a combined IGT/CFRD group. At baseline, a significant reduction in the majority of variables, including forced expiratory volume in one second (FEV₁) and maximal oxygen uptake (VO_2max), was observed in the CFRD (n = 19) group compared to NGT (n = 58). At follow-up, no significant differences were observed, and no interaction effect between CFRD status and time was identified. FEV₁ and VO_2max presented with varying directions and magnitudes of change within patients. In summary, patients with CFRD have a reduced aerobic and pulmonary function compared to non-CFRD counterparts, although such changes disappeared at follow up. Varying responses for FEV₁ and VO_2max highlight the need to consider both variables as independent markers of function in CF.

Effects of Exercise on Nutritional Status in People with Cystic Fibrosis: A Systematic Review

BACKGROUND

Physical exercise is an important part of regular care for people with cystic fibrosis (CF). It is unknown whether such exercise has beneficial or detrimental effects on nutritional status (body composition). Thus, the objective of this review was to evaluate the effect of exercise on measures of nutritional status in children and adults with CF.

METHODS

Standardized reporting guidelines for systematic reviews were followed and the protocol was prospectively registered. Multiple databases were utilized (e.g., PubMed, Scopus, and CINHAL). Two reviewers independently reviewed titles/abstracts and then the full text for selected studies.

RESULTS

In total, 924 articles were originally identified; data were extracted from 4 eligible studies. These four studies included only children; pulmonary function ranged from severe to normal, and the majority of participants were at or below their recommended weight. Exercise training did not worsen nutritional status in any study; two studies that included resistance exercise reported an increase in fat-free mass. Three of the four studies also reported increased aerobic capacity and/or muscle strength.

CONCLUSIONS

Exercise training can produce positive physiologic changes in children with CF without impairing their nutritional status. In fact, resistance exercise can help improve body mass. Much less is known about how exercise may affect adults or those who are overweight.

Effects of a Partially Supervised Conditioning Program in Cystic Fibrosis: An International Multicenter, Randomized Controlled Trial (ACTIVATE-CF)

Rationale: The long-term effects of vigorous physical activity (PA) on lung function in cystic fibrosis are unclear. Objectives: To evaluate effects of a 12-month partially supervised PA intervention using motivational feedback. Methods: In a parallel-arm multicenter randomized controlled trial (ACTIVATE-CF), relatively inactive patients aged at least 12 years were randomly assigned (1:1 ratio) to an intervention group or control group. The intervention group consented to add 3 hours of vigorous PA per week, whereas the control group was asked not to change their PA behavior. Primary endpoint was change in percent predicted FEV1 (ΔFEV1) at 6 months. Secondary endpoints included PA, exercise capacity, exercise motives, time to first exacerbation and exacerbation rates, quality of life, anxiety, depression, stress, and blood glucose control. Data were analyzed using mixed linear models. Measurements and Main Results: A total of 117 patients (40% of target sample size) were randomized to an intervention (n = 60) or control group (n = 57). After 6 months, ΔFEV1 was significantly higher in the control group compared with the intervention group (2.70% predicted [95% confidence interval, 0.13-5.26]; P = 0.04). The intervention group reported increased vigorous PA compared with the control group at each study visit, had higher exercise capacity at 6 and 12 months, and higher PA at 12 months. No effects were seen in other secondary outcomes. Conclusions: ACTIVATE-CF increased vigorous PA and exercise capacity, with effects carried over for the subsequent 6 months, but resulted in better FEV1 in the control group.

Physiological predictors of cardiorespiratory fitness in children and adolescents with cystic fibrosis without ventilatory limitation

Objectives:

[1] To investigate the cardiorespiratory fitness (CRF) levels in children and adolescents with cystic fibrosis (CF) with no ventilatory limitation (ventilatory reserve ⩾ 15%) during exercise, and [2] to assess which physiological factors are related to CRF.

Methods:

A cross-sectional study design was used in 8- to 18-year-old children and adolescents with CF. Cardiopulmonary exercise testing was used to determine peak oxygen uptake normalized to body weight as a measure of CRF. Patients were defined as having ‘low CRF’ when CRF was less than 82%predicted. Physiological predictors used in this study were body mass index z-score, P. Aeruginosa lung infection, impaired glucose tolerance (IGT) including CF-related diabetes, CF-related liver disease, sweat chloride concentration, and self-reported physical activity. Backward likelihood ratio (LR) logistic regression analysis was used.

Results:

Sixty children and adolescents (51.7% boys) with a median age of 15.3 years (25th–75th percentile: 12.9–17.0 years) and a mean percentage predicted forced expiratory volume in 1 second of 88.5% (±16.9) participated. Mean percentage predicted CRF (ppVO_2peak/kg) was 81.4% (±12.4, range: 51%–105%). Thirty-three patients (55.0%) were classified as having ‘low CRF’. The final model that best predicted low CRF included IGT (p = 0.085; Exp(B) = 6.770) and P. Aeruginosa lung infection (p = 0.095; Exp(B) = 3.945). This model was able to explain between 26.7% and 35.6% of variance.

Conclusions:

CRF is reduced in over half of children and adolescents with CF with normal ventilatory reserve. Glucose intolerance and P. Aeruginosa lung infection seem to be associated to low CRF in children and adolescents with CF.

The Exeter Activity Unlimited statement on physical activity and exercise for cystic fibrosis: methodology and results of an international, multidisciplinary, evidence-driven expert consensus

BACKGROUND

The roles of physical activity (PA) and exercise within the management of cystic fibrosis (CF) are recognised by their inclusion in numerous standards of care and treatment guidelines. However, information is brief, and both PA and exercise as multi-faceted behaviours require extensive stakeholder input when developing and promoting such guidelines.

METHOD

On 30th June and 1st July 2021, 39 stakeholders from 11 countries, including researchers, healthcare professionals and patients participated in a virtual conference to agree an evidence-based and informed expert consensus about PA and exercise for people with CF. This consensus presents the agreement across six themes: (i) patient and system centred outcomes, (ii) health benefits, iii) measurement, (iv) prescription, (v) clinical considerations, and (vi) future directions. The consensus was achieved by a stepwise process, involving: (i) written evidence-based synopses; (ii) peer critique of synopses; (iii) oral presentation to consensus group and peer challenge of revised synopses; and (iv) anonymous voting on final proposed synopses for adoption to the consensus statement.

RESULTS

The final consensus document includes 24 statements which surpassed the consensus threshold (>80% agreement) out of 30 proposed statements.

CONCLUSION

This consensus can be used to support health promotion by relevant stakeholders for people with CF.

Time Free From Hospitalization in Children and Adolescents With Cystic Fibrosis: Findings From FEV1, Lung Clearance Index and Peak Work Rate

BACKGROUND

An exercise test combined with a multiple breath washout nitrogen test (MBWN₂) may offer a comprehensive clinical evaluation of cystic fibrosis (CF) disease in children with normal spirometry. The purpose of the present study is to explore whether information derived from spirometry, MBWN₂, and exercise tests can help the CF multidisciplinary team to characterize time free from hospitalization due to pulmonary exacerbation (PE) in a cohort of pediatric patients with CF.

METHODS

This prospective observational study was carried out at the Lombardia Region Reference Center for Cystic Fibrosis in Milano, Italy. In 2015, we consecutively enrolled children and adolescents aged <18 years with spirometry, MBWN₂, and Godfrey exercise test performed during an outpatient visit.

RESULTS

Over a median follow-up time of 2.2 years (interquartile range [IQR], 2.01; 3.18), 28 patients aged between 13.0 and 17.4 years were included. When lung functions were outside the normal range, 50% of patients were hospitalized 4 months after the outpatient visit, and their response to exercise was abnormal (100%). Half of the individuals with normal forced expiratory volume in the first second (FEV₁) and abnormal lung clearance index (LCI) experienced the first hospital admission 9 months after the clinic visit, and 84.2% presented an abnormal response to exercise. Conversely, 15.8% had abnormal exercise responses when lung functions were considered normal, with half of the adolescents hospitalized at 11 months.

CONCLUSION

Maintaining ventilation homogeneity, along with a normal ability to sustain intense work, may have a positive impact on the burden of CF disease, here conceived as time free from hospitalization due to PE.

Development of the A-STEP: A new incremental maximal exercise capacity step test in cystic fibrosis

BACKGROUND

Exercise testing is important in people with cystic fibrosis (pwCF). The aim was to develop an incremental maximal step test to assess exercise capacity across the range of pwCF, without floor or ceiling effects, within restrictions of space, and infection prevention.

METHODS

The step test was developed in adults with stable CF. Subjects assisted in selecting: step height, start rate, increments, stage and test duration parameters. Equipment to externally pace and time the test and measure exercise parameters were selected. Reasons for stopping, criteria for achieving a maximal test, and key outcome measures were determined. Documentation to record and standardize the test and instructions to set up the metronome and timer App were developed. Infection control practices were considered.

RESULTS

Eight subjects were recruited to develop the Alfred Step Test Exercise Protocol (A-STEP) on a 20 cm portable step. The A-STEP package included a pretest information sheet, clinical assessment and instructions, recording worksheet, and the metronome/timer instructions. The test started at 18 steps/min. Each level increased by two steps/min to a maximum of 48 steps (Level 16). Results were presented as mean (SD) [range] for: age 30.63 (5.89) [21-39] years; FEV₁ 58.13 (18.33) [32-89]%; levels: 10.31 (3.29) [6-15.5]. The A-STEP required space of 2 m² and complied with current infection control guidelines.

CONCLUSIONS

The A-STEP is a new incremental maximal step test to assess exercise capacity in pwCF, without floor or ceiling effects. It addresses the issues of space restrictions and the need for strict infection prevention in the clinical setting.

Value of Cardiopulmonary Exercise Testing in the Prognosis Assessment of Chronic Obstructive Pulmonary Disease Patients: A Retrospective, Multicentre Cohort Study

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is one of the most common chronic diseases associated with high mortality. Previous studies suggested a prognostic role for peak oxygen uptake (VO2peak) assessed during cardiopulmonary exercise testing (CPET) in patients with COPD. However, most of these studies had small sample sizes or short follow-up periods, and despite their relevance, CPET parameters are not included in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) tool for assessment of severity.

OBJECTIVES

We therefore aimed to assess the prognostic value of CPET parameters in a large cohort of outpatients with COPD.

METHODS

In this retrospective, multicentre cohort study, medical records of patients with COPD who underwent CPET during 2004-2017 were reviewed and demographics, smoking habits, GOLD grade and category, exacerbation frequency, dyspnoea score, lung function measurements, and CPET parameters were documented. Relationships with survival were evaluated using Kaplan-Meier analysis, Cox regression, and receiver operating characteristic (ROC) curves.

RESULTS

Of a total of 347 patients, 312 patients were included. Five-year and 10-year survival probability was 75% and 57%, respectively. VO2peak significantly predicted survival (hazard ratio: 0.886 [95% confidence interval: 0.830; 0.946]). The optimal VO2peak threshold for discrimination of 5-year survival was 14.6 mL/kg/min (area under ROC curve: 0.713). Five-year survival in patients with VO2peak <14.6 mL/kg/min versus ≥ 14.6 mL/kg/min was 60% versus 86% in GOLD categories A/B and 64% versus 90% in GOLD categories C/D.

CONCLUSIONS

We confirm that VO2peak is a highly significant predictor of survival in COPD patients and recommend the incorporation of VO2peak into the assessment of COPD severity.

ARTP statement on cardiopulmonary exercise testing 2021

Cardiopulmonary exercise testing (CPET) has become an invaluable tool in healthcare, improving the diagnosis of disease and the quality, efficacy, assessment and safety of treatment across a range of pathologies. CPET's superior ability to measure the global exercise response of the respiratory, cardiovascular and skeletal muscle systems simultaneously in a time and cost-efficient manner has led to the application of CPET in a range of settings from diagnosis of disease to preoperative assessment. The Association for Respiratory Technology and Physiology Statement on Cardiopulmonary Exercise Testing 2021 provides the practitioner and scientist with an outstanding resource to support and enhance practice, from equipment to testing to leadership, helping them deliver a quality assured service for the benefit of all patient groups.

Aerobic fitness is associated with extracellular DNA levels in the sputum of patients with cystic fibrosis

AIMS

Patients with cystic fibrosis (CF) develop with progressive loss of lung function and aerobic fitness. However, the precise mechanisms of exercise intolerance are still controversial and appear to be influenced by several factors. This study aimed to evaluate the association of aerobic fitness with free DNA levels in the sputum of patients with CF.

METHODS

This cross-sectional study included patients with CF older than 6 years, free from active exacerbations, but who were able to produce spontaneously expectorated sputum. Extracellular DNA in the sputum was quantified. Lung function (spirometry) and aerobic fitness (cardiopulmonary exercise testing [CPET]) were performed. In addition, demographic, anthropometric and clinical data were collected.

RESULTS

Sixteen patients with a mean age of 19.4 ± 6.9 years and mean forced expiratory volume in the first second (FEV₁ ) of 51.8 ± 28.1 (% of predicted) were included. Mean peak oxygen consumption (VO₂ peak) was 32.8 ± 5.2 mL• kg^-1 • min^-1 , oxygen saturation at the end of the test was 90.6% ± 6.3% and mean extracellular DNA levels was 305.3 ± 153.6 μg/mL. Individuals with a VO₂ peak ≤ 30 mL• kg^-1 • min^-1 (P = .03) and a SpO₂ ≤ 90% at the end of the test (P = .03) had a greater amount of extracellular DNA in the sputum. The proportion of patients with reduced VO₂ peak in the group of patients with the lowest concentration of DNA in the sputum (<243 μg/mL) was significantly lower (0% vs 100%; P = .04).

CONCLUSION

There is an association between the presence of free DNA in sputum and aerobic fitness in patients with CF.

Rethinking physical exercise training in the modern era of cystic fibrosis: A step towards optimising short-term efficacy and long-term engagement

Exercise is considered as an important component of the package of care delivered to people with cystic fibrosis (pwCF). However, despite the well-known short-term physiological and psychological benefits, training effects are heterogenous and the transfer of structured exercise programmes to the daily life of pwCF is challenging. Training concepts and strategies developed over the last decades must be adapted to consider the aging population of pwCF with associated comorbidities, and also a new generation of young pwCF that are healthier than ever. In the present review we propose a new framework for optimising the choice among available exercise training procedures and we provide a theoretical and scientifically justified rationale for considering and testing new exercise training modalities. We propose a multidisciplinary approach, considering various physiological, psychological and logistical factors, with the aim to increase effects of exercise training and build positive long-term exercise behaviour.

Health-Related and Motor Performance-Related Fitness and Physical Activity Among Youth With Cystic Fibrosis

Little is known about motor competence and the longitudinal development of motor performance among youth with cystic fibrosis (CF). In this study, we assessed aspects of motor performance in different age groups of young patients with CF and compared them with a healthy reference group of same aged children. We also examined the development of motor performance among different age groups of these children with CF, using The Deutscher Motorik Test (DMT) to assess attributes of health-related and motor performance-related fitness. We used an incremental ergometer cycle test to determine maximal exercise capacity (expressed as peak workload). We evaluated and recorded habitual physical activity (PA) as measured by the number of steps per day and the time spent in different PA intensities (expressed in metabolic equivalents). In total, 31 children and adolescents with CF agreed to participate (13 girls,18 boys) aged 6-17 years (M = 11.3, SD =3.3 years); they had a mean one second forced expiratory volume (expressed as a percentage of predicted value [% pred]) of 87.2% (SD = 22.3%). We found their values of health-related and motor performance-related fitness to be significantly lower (p < 0.05) than those of their healthy peer participants. In contrast to the reference group, participants with CF up to 14 years of age showed a linear improvement in these values and in their PA, followed by a plateau or even a nonsignificant decrease after age 14. These findings have important implications for the development and prescription of exercise programs for children with CF. Besides aerobic and strength exercises, we recommend that neuromuscular training be integrated into exercise programs to improve the coordinative abilities of youth with CF. More attention should be paid to vulnerable older adolescents to ensure their long-term motivation to maintain exercise participation.

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.

Congenital central hypoventilation syndrome and ventilatory responses during cardiopulmonary exercise testing

BACKGROUND

Previous studies have shown evidence of hypoxemia and hypercapnia during cardiopulmonary exercise test (CPET) evaluation in children with congenital central hypoventilation syndrome (CCHS). However, there are no longitudinal studies which compared CPET findings to polysomnogram (PSG) or PHOX2B mutation, to date.

OBJECTIVES

To describe the longitudinal CPET findings in a cohort of children with CCHS and correlate the findings to the PSG results.

METHODS

This retrospective study was conducted in children with CCHS followed in the Long-term Ventilation Program at SickKids, Toronto, Canada between September, 2013 and January, 2020. CCHS genetic mutation, age of diagnosis, ventilatory support, family history, disease associations of CCHS, CPETs, and PSG parameters were recorded and analyzed.

RESULTS

A total of nine patients with CCHS (46 CPETs and 46 PSGs) were enrolled. Four (44.4%) children had polyalanine repeat mutations. The mean (SD) age at the time of diagnosis and duration of ventilatory usage were 3.2 ± 3.4 years and 11.5 ± 2.8 years, respectively. All abnormal CPETs had hypercapnia in at least 1 phase of the exercise test. Hypercapnia (12/46; 26.1%) at peak of exercise was the most common abnormality. None of the children experienced an oxygen desaturation below 90%. End-tidal CO₂ (PetCO₂ ) at rest and at peak exercise in the CPETs were significantly correlated with PSG TcCO₂ while PetCO₂ at anaerobic threshold was correlated with CO₂ in pre-PSG capillary blood gas.

CONCLUSION

Nocturnal hypoventilation may impact the CPET results in CCHS children. Serial CPETs should be considered standard clinical care for all CCHS children.

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.

Capacidade de exercício e nível de atividade física diária de crianças e adolescentes com fibrose cística: associação com estado nutricional, função pulmonar, hospitalização e uso de antibióticos

RESUMO O objetivo deste trabalho é avaliar a capacidade de exercício e nível de atividade física diária de crianças e adolescentes com fibrose cística e associar com estado nutricional, função pulmonar, tempo de hospitalização e uso de antibióticos. Trata-se de estudo transversal em indivíduos com fibrose cística entre 6 e 18 anos, registrando-se informações sobre perfil clínico, histórico de hospitalizações e uso de antibióticos. Os participantes foram submetidos à espirometria, bioimpedância, avaliação da capacidade de exercício com teste de Shuttle modificado (MST), o nível da atividade física foi medido por meio do questionário internacional de atividade física (IPAQ) e usando acelerômetro por 5 dias. Participaram 30 indivíduos com idade de 11,2 ± 3,6 anos e volume expirado forçado (VEF1) de 68,0 ± 24,8%. A mediana da distância percorrida no MST foi de 820 metros (66,3%) e demonstrou associação com a função pulmonar (r = 0,78), estado nutricional (r = 0,38), tempo de hospitalização (r = -0,42) e uso de antibióticos (r = -0,46). De acordo com o questionário, 20 pacientes (64,6%) foram classificados como sedentários, o acelerômetro revelou que os indivíduos passam 354,2 minutos em atividades sedentárias e apenas 14,9 minutos em atividades moderadas a vigorosas por dia. Quanto maior a porcentagem de tempo em atividade física moderada a vigorosa, maior o índice de massa corpórea (IMC) e menor o tempo de hospitalização. Assim, a capacidade de exercício e nível de atividade física em crianças e adolescentes com fibrose cística apresentou-se reduzida e associada com menores valores de IMC e aumento do tempo de hospitalização.

The impact of plasma 25-hydroxyvitamin D on pulmonary function and exercise physiology in cystic fibrosis: A multicentre retrospective study

BACKGROUND

A 25-hydroxyvitamin D (25OHD) may exert immunomodulatory effects on respiratory health, which may translate to improvements in exercise physiology. Thus, we aimed to investigate whether plasma 25OHD is associated with lung function and aerobic fitness in people with cystic fibrosis (pwCF).

METHODS

A multicentre retrospective review of pwCF (> 9 years old) attending the Royal Hospital for Sick Children (Edinburgh) or Wessex CF-Unit (Southampton) was performed between July 2017 and October 2019. Demographic and clinical data were collected. Plasma 25OHD measured closest in time to clinical cardiopulmonary exercise testing and/or spirometry [forced expiratory volume (FEV₁ )% predicted] was recorded. Pancreatic insufficiency was diagnosed based on faecal elastase of < 100 µg g^-1 . We performed multiple-regression analysis with aerobic fitness outcomes [peak oxygen uptake (VO_2 peak )] and FEV₁ % predicted as primary outcomes.

RESULTS

Ninety pwCF [mean ± SD age: 19.1 ± 8.6 years, 54 (60%) children, 48 (53%) males and 88 (98%) Caucasian] were included. 25OHD deficiency and insufficiency was 15 (17%) and 44 (49%), respectively. 25OHD deficiency and insufficiency was significantly associated with pancreatic insufficiency (χ²  = 4.8, p = 0.02). Plasma 25OHD was not significantly associated with FEV₁ % predicted (r²  = 0.06, p = 0.42, 95% CI = -0.09 to 0.19) or VO_2 peak (r²  = 0.04, p = 0.07, 95% CI = -011 to 0.005) in all pwCF. However, 25OHD was significantly associated with both FEV₁ % (r²  = 0.15, p = 0.02, 95% CI = 1.99-2.64) and VO_2 peak (r²  = 0.13, p = 0.05, 95% CI = -0.26 to -0.005) in the paediatric cohort.

CONCLUSIONS

We showed that 25OHD is associated with improved lung function and aerobic fitness in children and adolescents with CF. Mechanistic and high-quality prospective studies including both lung function and aerobic fitness as primary outcomes are now warranted.

Exercise testing and exercise training within cystic fibrosis centres across Australia and New Zealand: what is considered important and what is current practice?

BACKGROUND

Within Australian and New Zealand cystic fibrosis (CF) centres, exercise testing and exercise training are common components of clinical care, but current practices regarding these components have not been reported.

AIM

To determine the extent, scope and importance placed on exercise testing and exercise training within CF centres across Australia and New Zealand.

METHODS

Information pertaining to exercise testing and training practices was sought by administering a survey to health professionals working in CF centres across Australia and New Zealand. The survey comprised five sections (46 questions) and was sent via an online link (Qualtrics). Response rate was optimised using the Dillman approach. Approval for this study was granted from the Human Research Ethics Committee at Curtin University (HRE2018-074). Completion of the survey was taken as informed consent.

RESULTS

A response rate of 80% (n = 32/40) was achieved. Each state/territory in Australia, except the Northern Territory was represented in the survey responses. Eight of the 12 major regions in New Zealand were also represented. Regarding tests of exercise capacity, field-based tests were performed more commonly than laboratory-based tests (n = 28/32; 88% vs n = 11/32 centres; 34%; difference: 54%; 95% confidence interval 31-70%). Most (89%) respondents perceived field tests to be at least 'somewhat' important, whereas 91% of respondents perceived laboratory tests to be 'a little' to 'somewhat' important. Physical activity and/or exercise were discussed by at least one health professional in the CF team at every clinic appointment and/or annual review. Most centred offered outpatient exercise training each year to their patients (n = 24/32; 75%).

CONCLUSION

This survey captures the current practices of exercise testing and training in CF centres across Australia and New Zealand.

Exercise Intolerance in Cystic Fibrosis: Importance of Skeletal Muscle

PURPOSE

Exercise intolerance, evaluated by O2 consumption, predicts mortality in cystic fibrosis (CF). People with CF exhibit skeletal muscle dysfunctions that may contribute to an imbalance between O2 delivery and utilization. Sildenafil, a phosphodiesterase type 5 inhibitor, increases blood flow and improves O2 consumption, although the exact mechanisms in CF have yet to be elucidated. Thus, we hypothesized that exercise intolerance in CF is limited primarily by an impaired skeletal muscle O2 utilization, and sildenafil improves exercise tolerance in CF by addressing this mismatch between O2 demand and extraction.

METHODS

Fifteen individuals with mild to moderate CF and 18 healthy controls completed an incremental exercise test and measurements of gaseous exchange, chronotropic response, hemodynamics, and O2 extraction and utilization. People with CF also completed a 4-wk treatment with sildenafil with a subsequent follow-up evaluation after treatment.

RESULTS

Skeletal muscle O2 extraction and utilization during exercise were reduced in people with CF when compared with controls. Exercise capacity in our CF population was minimally limited by hemodynamic or chronotopic responses, whereas peripheral O2 extraction was more closely associated with exercise capacity. The study also demonstrated that 4 wk of sildenafil improved skeletal muscle O2 utilization during exercise to similar values observed in healthy individuals.

CONCLUSIONS

Individuals with mild to moderate CF exhibit exercise intolerance secondary to a reduction in O2 utilization by the exercising skeletal muscle. The present study demonstrated that 4 wk of sildenafil treatment improves the capacity of the skeletal muscle to use O2 more efficiently during exercise. Findings from the present study highlight the importance of targeting skeletal muscle O2 utilization to improve exercise tolerance in CF.

Trainability of Health-Related and Motor Performance Fitness in Adults with Cystic Fibrosis within a 12-Month Partially Supervised Exercise Program

Background

Regular physical activity plays an important role in the treatment of patients with cystic fibrosis (CF). This study is aimed at investigating the effects of a 12-month partially supervised exercise program on attributes of health-related and motor performance fitness, lung function (ppFEV1), BMI, and habitual physical activity (HPA, steps/day) in adults with CF.

Methods

Attributes of health-related and motor performance fitness were examined at the beginning (T0), after 6 (T1), and 12 months (T2) on the basis of five test items: forward bend (FB), bent knee hip extension (HE), plank leg raise (PLR), standing long jump (SLJ), and standing on one leg (OLS). Additionally, we recorded HPA by accelerometry, peak exercise performance (W _peak) by an incremental cycle test, ppFEV1, and BMI. During the first six months, there was close supervision by an experienced sport therapist.

Results

26 CF patients (8 female, mean age 26.5 ± 7.9 years; ppFEV1 53.7 ± 21.0) completed the exercise program. Significant improvements were recorded from T0 to T1 (FB: p ≤ 0.05; PLR, OLS: p ≤ 0.01) and from T0 to T2 (FB, PLR: p ≤ 0.01 and HE, OLS: p ≤ 0.05). W _peak, ppFEV1, BMI, and HPA showed no significant improvement between the single test points and over the entire study period (all p > 0.05).

Conclusion

Our results show trainability of adults with CF in aspects of health-related and motor performance fitness during a partially supervised exercise program. Close supervision positively influences the results. Using a simple test setup seems to be a promising tool for evaluating the effects of exercise programs in CF and could serve as an additional outcome parameter in future clinical trials. Trial registration: ClinicalTrials.gov (retrospectively registered May 8, 2018).

Measurement properties of the one-minute sit-to-stand test in children and adolescents with cystic fibrosis: A multicenter randomized cross-over trial

Background

Functional exercise capacity assessment is recommended in children with cystic fibrosis (CF). The six-minute walk test (6MWT) is a valid evaluation of exercise capacity but can be technically complex. Inversely, the sit-to-stand test (STST) is a simple method to evaluate exercise capacity, and is validated in healthy children and adults with CF. This study aimed to evaluate STST measurement properties in children and adolescents with CF.

Methods

In this multicenter study, children with CF (6 to 18 years) performed two iterations of both the STST and the 6MWT in a randomized order. Criterion validity was determined by assessing correlations between STST repetitions and 6MWT distance (6MWD). Intra-rater reliability, test-retest repeatability, mean bias and limits of agreement were also assessed. Relationships with other outcomes (i.e. respiratory and quadriceps muscle strength) and cardio-respiratory responses were analysed for both tests.

Results

Thirty-six children with CF were included (mean age 12.0 ±3.5 years and FEV1 95.8 ±25.0%). On average, 39.6 ±10.5 repetitions were performed during the STST and mean 6MWD was 596.0 ±102.6 meters. STST number of repetitions was significantly correlated with 6MWD (r = 0.48; p<0.01). Both tests had very good intra-rater reliability (ICC_STST = 0.91 (95%CI 0.76–0.96) and ICC_6MWT = 0.94 (95%CI 0.85–0.97)), and a significant test-retest learning effect. The number of STST repetitions was not correlated with quadriceps or respiratory muscle strength test, and the STST induced fewer cardio-respiratory responses than the 6MWT.

Conclusions

The STST is an easy-to-use functional test with moderate criterion validity when compared to the 6MWT in children with CF, probably because both tests measure different components of functional exercise capacity. The STST is useful when the 6MWT is unfeasible, however further investigations are required to explore the clinical implications of STST results in children with CF.

Clinical trial registration

NCT03069625.

The modified shuttle test as a predictor of risk for hospitalization in youths with cystic fibrosis: A two-year follow-up study: Modified shuttle test as a predictor of hospitalization

BACKGROUND

Patients with cystic fibrosis (CF) present exercise intolerance and episodes of pulmonary exacerbations. This study aimed to evaluate the association of the distance covered on the modified shuttle test (MST), as well as other clinical variables (anthropometry, chronic colonization by Pseudomonas aeruginosa, lung function), with the risk of hospitalization for pulmonary exacerbation.

METHODS

Cohort study including CF patients older than 6 years, from two specialized CF centers. All patients underwent a MST and a lung function test at the time of inclusion. Demographic, anthropometric and clinical data were collected. Free time until the first hospitalization, total days of hospitalization and use of antibiotics during the two years of follow-up were recorded.

RESULTS

Sixty-seven patients with a mean (SD) age of 12.4 (5.2) years and forced expiratory volume in the first second (FEV₁) of 78.7% (22.4) were included. The mean distance covered (m) in the MST was 775.6 (255.7) (73.4 ± 19.5% of predicted). The distance achieved (MST) was considered as the main independent variable to predict the risk of hospitalization (Cox HR 0.97, p = 0.029). Patients who walked a distance of less than 80% of predicted in the MST showed an increase of 3.9 (95%CI 1.0-15.3) in the relative risk for hospitalization and significantly higher total number of days of hospitalization (p = 0.022).

CONCLUSION

There is an association between the distance covered in the MST and the risk of hospitalization in youths with CF. Patients with reduced exercise capacity presented a 3.9 times increase in the relative risk for hospitalization due to pulmonary exacerbation.

Toward the Establishment of New Clinical Endpoints for Cystic Fibrosis: The Role of Lung Clearance Index and Cardiopulmonary Exercise Testing

As Cystic Fibrosis (CF) treatment advances, research evidence has highlighted the value and applicability of Lung Clearance Index and Cardiopulmonary Exercise Testing as endpoints for clinical trials. In the context of these new endpoints for CF trials, we have explored the use of these two test outcomes for routine CF care. In this review we have presented the use of these methods in assessing disease severity, disease progression, and the efficacy of new interventions with considerations for future research.

Exercise-induced electrocardiographic changes after treadmill exercise testing in healthy children: A comprehensive study

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VO2max as an exercise tolerance endpoint in people with cystic fibrosis: Lessons from a lumacaftor/ivacaftor trial

BACKGROUND

The impact of lumacaftor/ivacaftor on exercise tolerance in people with cystic fibrosis (CF) has not been thoroughly studied.

METHODS

We conducted a multisite Phase 4 trial comparing the impact of lumacaftor/ivacaftor on exercise tolerance with that of placebo in participants ≥ 12 years of age with CF homozygous for F508del-CFTR. The primary endpoint was relative change from baseline in maximum oxygen consumption (VO_2max) during cardiopulmonary exercise testing (CPET) at Week 24. The key secondary endpoint was relative change from baseline in exercise duration during CPET at Week 24. Other secondary endpoints included changes in other indices of exercise tolerance and changes in CF assessments; safety and tolerability were assessed as an endpoint.

RESULTS

Seventy participants were randomized to receive lumacaftor/ivacaftor (n = 34) or placebo (n = 36). The least-squares mean difference for lumacaftor/ivacaftor versus placebo in relative change in VO_2max from baseline at Week 24 was -3.2% (95% CI: -9.2, 2.9; P=0.3021); the least-squares mean difference in relative change from baseline in exercise duration at Week 24 was -3.2% (95% CI: -8.0, 1.6). Safety results were consistent with the known lumacaftor/ivacaftor safety profile.

CONCLUSIONS

Definitive conclusions regarding the impact of lumacaftor/ivacaftor on exercise tolerance cannot be drawn from these results; however, multicenter studies using CPETs can be reliably performed with multiple time points and conventional methods, provided that calibration can be achieved. Future studies of exercise tolerance may benefit from lessons learned from this study. NCT02875366.