Exercise testing in pediatric lung transplant candidates with cystic fibrosis

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.

The correlation between 6-min walk test and respiratory parameters in children with cystic fibrosis

BACKGROUND

The 6-min walk test (6MWT) is a sub-maximal exercise test and has been widely used for evaluating of exercise capacity of patients with cystic fibrosis (CF) in recent years. Few studies have examined the relationship between 6MWT and parameters used to assess the severity of the disease in children with CF. In this study, we have examined this relationship to find out if 6MWT can be a marker of the severity of cystic fibrosis.

METHODS

A cross-sectional study was done to analyze the correlations among spirometry parameters, body mass index (BMI), chest tomography (CT), and 6MWT. CF patients, aged 7-14 years, were involved.

RESULTS

Seventy-six patients, 32F/44M, mean age 10.49 ± 3.18 years, were studied. The mean distance in 6MWT was 447 ± 84.1. The following correlations versus distance were found: FEV1 (r = 0.255, p = 0.026), FVC(r = 0.285, p = 0.013), FEF25-75% (r = 0.546, p < 0.001), BMI (r = 0.163, p = 0.160), and CT (r = 0.075, p = 0.520).The following correlations versus O₂ saturation (SpO₂) decline were found: FEV1 (r = -0.393, p < 0.001), FVC (r = -0.431, p < 0.001), FEF25-75% (r = -0.296, p = 0.010), BMI (r = 0.042, p = 0.721), and CT (r = -0.196, p = 0.090). There was a significant correlation between 6MWT (distance and SpO₂ decline) and pulmonary function test. There was no significant correlation between BMI, chest CT, and 6MWT.

CONCLUSIONS

6MWT can be applied beside spirometry and chest CT for CF patients follow up.

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.

The Utility of the Sit-to-Stand Test for Inpatients in the Acute Hospital Setting After Lung Transplantation

OBJECTIVE

Measurement of physical function is important to guide physical therapy for patients post-lung transplantation (LTx). The Sit-to-Stand (STS) test has proven utility in chronic disease, but psychometric properties post-LTx are unknown. The study aimed to assess reliability, validity, responsiveness, and feasibility of the 60-second STS post-LTx.

METHODS

This was a measurement study in 62 inpatients post-LTx (31 acute postoperative; 31 medical readmissions). Interrater reliability was assessed with 2 STS tests undertaken by different assessors at baseline. Known group validity was assessed by comparing STS repetitions in postoperative and medical groups. Content validity was assessed using comparisons to knee extensor and grip strength, measured with hand-held dynamometry. Criterion validity was assessed by comparison of STS repetitions and 6-minute walk distance postoperatively. Responsiveness was assessed using effect sizes over inpatient admission.

RESULTS

Median (interquartile range) age was 62 (56-67) years; time post-LTx was 5 (5-7) days postoperative and 696 (244-1849) days for medical readmissions. Interrater reliability was excellent (intraclass correlation coefficient type 2,1 = 0.96), with a mean learning effect of 2 repetitions. Repetitions were greater for medical at baseline (mean 18 vs 8). More STS repetitions were associated with greater knee extensor strength (postoperative r = 0.57; medical r = 0.47) and 6-minute walk distance (postoperative r = 0.68). Effect sizes were 0.94 and 0.09, with a floor effect of 23% and 3% at baseline (postoperative/medical) improving to 10% at discharge. Patients incapable of attempting a STS test were excluded, reducing generalizability to critical care. Physical rehabilitation was not standardized, possibly reducing responsiveness.

CONCLUSIONS

The 60-second STS demonstrated excellent interrater reliability and moderate validity and was responsive to change postoperatively.

IMPACT

The 60-second STS represents a safe, feasible functional performance tool for inpatients post-LTx. Two tests should be completed at each time point.

Timing it right: the challenge of recipient selection for lung transplantation

Selection criteria for the referral and potential listing of patients for lung transplantation (LTx) have changed considerably over the last three decades but one key maxim prevails, the ultimate focus is to increase longevity and quality of life by careful utilization of a rare and precious resource, the donor organs. In this article, we review how the changes have developed and the outcomes of those changes, highlighting the impact of the lung allocation score (LAS) system. Major diseases, including interstitial lung disease (ILD), chronic obstructive pulmonary disease and pulmonary hypertension are considered in detail as well as the concept of retransplantation where appropriate. Results from bridging to LTx using extracorporeal membrane oxygenation (ECMO) are discussed and other potential contraindications evaluated such as advanced age, frailty and resistant infections. Given the multiplicity of risk factors it is a credit to those working in the field that such excellent and improving results are obtained with an ongoing dedication to achieving best practice.

Cardiopulmonary exercise testing with supramaximal verification produces a safe and valid assessment of V̇o2max in people with cystic fibrosis: a retrospective analysis

The validity and safety of using supramaximal verification (S_max) to confirm a maximal effort during cardiopulmonary exercise testing (CPET) in people with cystic fibrosis (CF) and/or those with severe disease has been questioned. Therefore, this study aimed to investigate these concerns in children, adolescents, and adults with mild-to-severe CF lung disease. Retrospective analysis of 17 pediatric and 28 adult participants with CF [age range: 9.2-62.9 y; forced expiratory volume in 1 s: 66.7% (range: 29.9%-102.3%); 30 men] who completed a routine ramp-incremental cycling test to determine peak oxygen uptake (V̇o_2peak) was studied. Maximal oxygen uptake (V̇o_2max) was subsequently confirmed by S_max at 110% of peak power output. All participants satisfied the criteria to verify a maximal effort during CPET. However, S_max-V̇o_2peak exceeded ramp-V̇o_2peak in 3/14 (21.4%) of pediatric and 6/28 (21.4%) adult exercise tests. A valid measurement of V̇o_2max was attained in 85.7% of pediatric and 96.4% of adult exercise tests, as S_max-V̇o_2peak did not exceed ramp-V̇o_2peak by >9%. Adults ( n = 9) experienced a ≥5% reduction in arterial O₂ saturation during CPET, 4 during both the ramp and S_max, 3 during only the ramp, and 2 during only S_max. S_max did not significantly worsen perceived breathing effort, chest tightness, throat narrowing, or exertion compared with ramp-incremental testing. Given the clinical importance of aerobic fitness in people with CF, incorporating S_max is recommended to provide a safe and valid measure of V̇o_2max in children, adolescents, and adults who span the spectrum of CF disease severity. NEW & NOTEWORTHY Incorporating supramaximal verification into cardiopulmonary exercise testing protocols did not increase the frequency of adverse events or perceived discomfort versus a single-phase incremental exercise test in people with mild-to-severe cystic fibrosis. Furthermore, a valid measure of maximal oxygen uptake (V̇o_2max) was obtained from 85.7% of pediatric and 96.4% of adult exercise tests, whereas peak oxygen uptake underestimated aerobic fitness in comparison with V̇o_2max in 21.4% of cases (by up to 24.4%).

Exercise testing in cystic fibrosis: Who and why?

Annual review exercise testing is recommended by the Cystic Fibrosis (CF) Trust. Testing to date has focused on evaluating aerobic fitness, a key prognostic indicator. Tests available range from simple field tests, to comprehensive evaluations of aerobic exercise (dys)function - cardiopulmonary exercise testing (CPET). 'Field tests', although easy to perform are limited in the information they provide,whereas CPET, the 'gold standard' measure of aerobic fitness, is recommended as the first-choice exercise test by the European CF Society Exercise Working Group. CPET offers a precise cardiovascular, respiratory and metabolic evaluation of exercise capacity, including assessment of mechanism(s) of exercise limitation.

[Effect of a surgical mask on six minute walking distance]

INTRODUCTION

Six minutes walking test (6MWT) is regularly used in pulmonology. To minimize the risk of cross-infection, some patients must wear surgical mask at rest and sometimes during exercise.

AIM OF THE STUDY

To evaluate the effect of wearing a surgical mask during 6MWT in healthy subjects.

MATERIAL AND METHOD

It is a prospective study on 44 healthy subjects. After a first 6MWT for training, they performed randomly two 6MWT: with or without a surgical mask. Distance and dyspnea, heart rate and saturation variations were recorded.

RESULTS

Distance was not modified by the mask (P=0.99). Dyspnea variation was significantly higher with surgical mask (+5.6 vs. +4.6; P<0.001) and the difference was clinically relevant. No difference was found for the variation of other parameters.

CONCLUSION

Wearing a surgical mask modifies significantly and clinically dyspnea without influencing walked distance.

Aerobic fitness is associated with lower risk of hospitalization in children with cystic fibrosis

BACKGROUND

Children with cystic fibrosis (CF) often have to be hospitalized because of acute exacerbation of their respiratory symptoms. Given the fact that improved peak oxygen uptake (VO2peak ) is positively associated with lung function and overall health in children with CF, this study examined the association between VO2peak and the need for hospitalization in a cohort of pediatric CF patients.

METHODS

In a 3-year study, 77 CF children with mild-to-moderately severe CF (forced expiratory volume in 1 sec [FEV1 ] ≥ 50%) underwent a maximal exercise test to determine VO2peak . Anthropometric, lung function and muscle strength measurements were also conducted and dates of hospitalization were recorded for the study period. Associations were then determined between the variables recorded and hospitalization by univariate and multivariate Cox proportional hazards regression analyses.

RESULTS

VO2peak was 38.6 ± 6.7 ml kg(-1)  min(-1) for boys and 31.9 ± 6.9 ml kg(-1)  min(-1) for girls. In multivariate analyses, VO2peak was the only variable significantly associated with time to hospitalization (hazard ratio 0.91, P = 0.03).

CONCLUSION

A significant association was detected between greater aerobic fitness, and lower risk of hospitalization. Because hospitalization due to respiratory exacerbation is a powerful prognostic factor, our findings provide further support for the importance of aerobic fitness evaluation in the management of children with mild-to-moderately severe CF.

Practical guidelines: lung transplantation in patients with cystic fibrosis

There are no European recommendations on issues specifically related to lung transplantation (LTX) in cystic fibrosis (CF). The main goal of this paper is to provide CF care team members with clinically relevant CF-specific information on all aspects of LTX, highlighting areas of consensus and controversy throughout Europe. Bilateral lung transplantation has been shown to be an important therapeutic option for end-stage CF pulmonary disease. Transplant function and patient survival after transplantation are better than in most other indications for this procedure. Attention though has to be paid to pretransplant morbidity, time for referral, evaluation, indication, and contraindication in children and in adults. This review makes extensive use of specific evidence in the field of lung transplantation in CF patients and addresses all issues of practical importance. The requirements of pre-, peri-, and postoperative management are discussed in detail including bridging to transplant and postoperative complications, immune suppression, chronic allograft dysfunction, infection, and malignancies being the most important. Among the contributors to this guiding information are 19 members of the ECORN-CF project and other experts. The document is endorsed by the European Cystic Fibrosis Society and sponsored by the Christiane Herzog Foundation.

Estimating peak oxygen uptake in adolescents with cystic fibrosis

OBJECTIVES

To predict peak oxygen uptake (VO2 peak) from the peak work rate (W peak) obtained during a cycle ergometry test using the Godfrey protocol in adolescents with cystic fibrosis (CF), and assess the accuracy of the model for prognostication clustering.

METHODS

Out of our database of anthropometric, spirometric and maximal exercise data from adolescents with CF (N=363; 140 girls and 223 boys; age 14.77 ± 1.73 years; mean expiratory volume in 1 s (FEV1%pred) 86.82 ± 17.77%), a regression equation was developed to predict VO2 peak (mL/min). Afterwards, this prediction model was validated with cardiopulmonary exercise data from another 60 adolescents with CF (28 girls, 32 boys; mean age 14.6 ± 1.67 years; mean FEV1%pred 85.43 ± 20.01%).

RESULTS

We developed a regression model VO2 peak (mL/min)=216.3-138.7 × sex (0=male; 1=female)+11.5 × W peak; R(2)=0.91; SE of the estimate (SEE) 172.57. A statistically significant difference (107 mL/min; p<0.001) was found between predicted VO2 peak and measured VO2 peak in the validation group. However, this difference was not clinically relevant because the difference was within the SEE of the model. Furthermore, we found high positive predictive and negative predictive values for the model for prognostication clustering (PPV 50-87% vs NPV 82-94%).

CONCLUSIONS

In the absence of direct VO2 peak assessment it is possible to estimate VO2 peak in adolescents with CF using only a cycle ergometer. Furthermore, the regression model showed to be able to discriminate patients in different prognosis clusters based on exercise capacity.

Pretransplant six-minute walk test predicts peri- and post-operative outcomes after pediatric lung transplantation

The purpose of the pretransplant assessment in lung transplantation is to determine a patient's need for transplant as well as their potential survival post-procedure. In 2005, the UNOS introduced the LAS, a calculation based on multiple physiologic measures to determine need and likelihood for survival. Measures include NYHA class and the 6-MWT. Some adult studies indicate a positive correlation with 6-MWT and waiting list survival. In pediatric/adolescent patients, there are minimal data regarding the predictive value of physiologic markers in either wait list survival or post-transplant outcome. A retrospective cohort study of 60 consecutive lung transplantations from 1990 to 2008 was performed at a pediatric tertiary care facility. Functional pretransplant assessments were abstracted from the medical record and compared with outcomes after transplantation.

RESULTS

a 6-MWT of >1000 ft (305 m) prior to transplantation correlated with a shorter ICU stay (7 vs. 11 days, p = 0.046) and fewer days of mechanical ventilation (2 vs. 4, p = 0.04). A pretransplant 6-MWT greater than 750 ft (229 m) correlated with shorter overall hospitalization (37 vs. 20 days, p = 0.03). Measuring pretransplant 6-MWT tests for pediatric patients is valuable in predicting peri-operative outcomes after lung transplantation.

Towards an individualized protocol for workload increments in cardiopulmonary exercise testing in children and adolescents with cystic fibrosis

BACKGROUND

There is no single optimal exercise testing protocol for children and adolescents with cystic fibrosis (CF) that differs widely in age and disease status. The aim of this study was to develop a CF-specific, individualized approach to determine workload increments for a cycle ergometry testing protocol.

METHODS

A total of 409 assessments consisting of maximal exercise data, anthropometric parameters, and lung function measures from 160 children and adolescents with CF were examined. 90% of the database was analyzed with backward linear regression with peak workload (W(peak)) as the dependent variable. Afterwards, we [1] used the remaining 10% of the database (model validation group) to validate the model's capacity to predict W(peak) and [2] validated the protocol's ability to provide a maximal effort within a 10±2 minute time frame in 14 adolescents with CF who were tested using this new protocol (protocol validation group).

RESULTS

No significant differences were seen in W(peak) and predicted W(peak) in the model validation group or in the protocol validation group. Eight of 14 adolescents with CF in the protocol validation group performed a maximal effort, and seven of them terminated the test within the 10±2 minute time frame. Backward linear regression analysis resulted in the following equation: W(peak) (W)=-142.865+2.998×Age (years)-19.206×Sex (0=male; 1=female)+1.328×Height (cm)+23.362×FEV(1) (L) (R=.89; R(2)=.79; SEE=21). Bland-Altman analysis showed no systematic bias between the actual and predicted W(peak).

CONCLUSION

We developed a CF-specific linear regression model to predict peak workload based on standard measures of anthropometry and FEV(1), which could be used to calculate individualized workload increments for a cycle ergometry testing protocol.