Lung clearance index (LCI) as a predictor of exercise limitation among CF patients

Comparative sensitivity of early cystic fibrosis lung disease detection tools in school aged children

BACKGROUND

Effective detection of early lung disease in cystic fibrosis (CF) is critical to understanding early pathogenesis and evaluating early intervention strategies. We aimed to compare ability of several proposed sensitive functional tools to detect early CF lung disease as defined by CT structural disease in school aged children.

METHODS

50 CF subjects (mean±SD 11.2 ± 3.5y, range 5-18y) with early lung disease (FEV1≥70 % predicted: 95.7 ± 11.8 %) performed spirometry, Multiple breath washout (MBW, including trapped gas assessment), oscillometry, cardiopulmonary exercise testing (CPET) and simultaneous spirometer-directed low-dose CT imaging. CT data were analysed using well-evaluated fully quantitative software for bronchiectasis and air trapping (AT).

RESULTS

CT bronchiectasis and AT occurred in 24 % and 58 % of patients, respectively. Of the functional tools, MBW detected the highest rates of abnormality: Scond 82 %, MBWTG RV 78 %, LCI 74 %, MBWTG IC 68 % and Sacin 51 %. CPET VO2peak detected slightly higher rates of abnormality (9 %) than spirometry-based FEV1 (2 %). For oscillometry AX (14 %) performed better than Rrs (2 %) whereas Xrs and R5-19 failed to detect any abnormality. LCI and Scond correlated with bronchiectasis (r = 0.55-0.64, p < 0.001) and AT (r = 0.73-0.74, p < 0.001). MBW-assessed trapped gas was detectable in 92 % of subjects and concordant with CT-assessed AT in 74 %.

CONCLUSIONS

Significant structural and functional deficits occur in early CF lung disease, as detected by CT and MBW. For MBW, additional utility, beyond that offered by LCI, was suggested for Scond and MBW-assessed gas trapping. Our study reinforces the complementary nature of these tools and the limited utility of conventional oscillometry and CPET in this setting.

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.

Exercise as an Airway Clearance Technique in people with Cystic Fibrosis (ExACT-CF): rationale and study protocol for a randomised pilot trial

Background

Chest physiotherapy is an established cornerstone of care for people with cystic fibrosis (pwCF), but is often burdensome. Guidelines recommend at least one chest physiotherapy session daily, using various airway clearance techniques (ACTs). Exercise (with huffs and coughs) may offer an alternative ACT, however the willingness of pwCF to be randomised into a trial needs testing. The 'ExACT-CF: Exercise as an Airway Clearance Technique in people with Cystic Fibrosis' trial will test the feasibility of recruiting pwCF to be randomised to continue usual care (chest physiotherapy) or replace it with exercise ACT (ExACT) for 28-days. Secondary aims include determining the short-term clinical impact (and safety) of stopping routine chest physiotherapy and replacing it with ExACT, and effects on physical activity, sleep, mood, quality of life and treatment burden, alongside preliminary health economic measures and acceptability.

Methods

Multi-centre, two-arm, randomised (1:1 allocation using minimisation), pilot trial at two sites. Fifty pwCF (≥10 years, FEV 1 >40% predicted, stable on Elexacaftor/Tezacaftor/Ivacaftor (ETI)) will be randomised to an individually-customised ExACT programme (≥once daily aerobic exercise of ≥20-minutes duration at an intensity that elicits deep breathing, with huffs and coughs), or usual care. After baseline assessments, secondary outcomes will be assessed after 28-days, with additional home lung function and exacerbation questionnaires at 7, 14 and 21-days, physical activity and sleep monitoring throughout, and embedded qualitative and health-economic components. Feasibility measures include recruitment, retention, measurement completion, adverse events, interviews exploring the acceptability of trial procedures, and a trial satisfaction questionnaire.

Discussion

Co-designed with the UK CF community, the ExACT-CF pilot trial is the first multi-centre RCT to test the feasibility of recruiting pwCF stable on ETI into a trial investigating ExACT. This pilot trial will inform the feasibility, design, management, likely external validity for progression to a main phase randomised controlled trial.

Registration

Clinicaltrials.gov ( NCT05482048).

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.

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.

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 capacity and ventilation inhomogeneity in cystic fibrosis: A cross-sectional study

BACKGROUND

Lung clearance index (LCI_2.5 ) is a marker of overall lung ventilation inhomogeneity and has proven to be able to detect early peripheral damage in subjects with cystic fibrosis (CF), with greater sensitivity than conventional spirometry. Combining its sensitivity with the output of an incremental exercise testing, we hypothesized that any sign of ventilation inhomogeneity in subjects without severe airflow obstruction and with a normal exercise tolerance could be relevant for the CF team, tracking early lung disease and potential exercise limiting factors.

METHODS

Patients with CF in clinical stable conditions were recruited between 2015 and 2017. Available spirometry, nitrogen multiple-breath washout test and symptoms-limited exercise testing performed as parts of patients' annual routine evaluation were considered for this cross-sectional study. To describe the relationship between exercise intensity and ventilation inhomogeneity, a linear regression analysis was performed using backward elimination based on Akaike information criteria.

RESULTS

Seventy-seven patients (38 females) were included. S_acin and LCI_2.5 were significantly higher in patients with an overall reduced exercise tolerance. Peak work developed during exercise was associated with body mass index (b = 5.25; 95% confidence interval [CI] = 1.53-8.98), forced expiratory volume in 1 second (FEV₁ ; b = 3.71; 95% CI = 1.96-5.46), Pseudomonas aeruginosa chronic infection (b = -8.84; 95% CI = -15.84 to -1.84) but not with LCI_2.5 .

CONCLUSION

Exercise capacity and airflow obstruction are associated in this Italian CF cohort. Considering the greater discriminatory power of LCI_2.5 over FEV₁ and peak work, the Godfrey protocol without gas analysis cannot provide detailed information about lung function or efficiency. However, this incremental protocol without gas exchange measures can still provide the CF team with information about exercise tolerance and disability.

Does Pseudomonas aeruginosa Colonization Affect Exercise Capacity in CF?

Introduction

Cardio-Pulmonary Exercise Testing (CPET) has been recognized as a valuable method in assessing disease burden and exercise capacity among CF patients.

Aim

To evaluate whether Pseudomonas aeruginosa colonization status affects Exercise Capacity, LCI and High-Resolution Computed Tomography (HRCT) indices among patients with CF; to check if Pseudomonas colonization can predict exercise intolerance.

Subjects

Seventy-eight (78) children and adults with CF (31 males) mean (range) age 17.08 (6.75; 24.25) performed spirometry, Multiple Breath Washout (MBW) and CPET along with HRCT on the same day during their admission or follow up visit.

Results

78 CF patients (mean FEV1: 83.3% mean LCI: 10.9 and mean VO₂ peak: 79.1%) were evaluated: 33 were chronically colonized with Pseudomonas aeruginosa, 24 were intermittently colonized whereas 21 were Pseudomonas free. Statistically significant differences were observed among the three groups in: peak oxygen uptake % predicted (VO₂ peak% (p < 0.001), LCI (p < 0.001), as well as FEV1% (p < 0.001) and FVC% (p < 0.001). Pseudomonas colonization could predict VO₂ peak% (p < 0.001, r²: −0.395).

Conclusion

Exercise capacity as reflected by peak oxygen uptake is reduced in Pseudomonas colonized patients and reflects lung structural damages as shown on HRCT. Pseudomonas colonization could predict exercise limitation among CF patients.

Cystic fibrosis year in review 2018, part 1

Cystic fibrosis research and case reports were robust in the year 2018. This report summarizes research and cases related to Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) modulator therapies, inflammation and infection, epidemiology and the physiologic, and imaging assessment of disease.