Lung clearance index to characterize clinical phenotypes of children and adolescents with cystic fibrosis.

BACKGROUND: Lung clearance index (LCI) is accepted as an early marker of lung disease in cystic fibrosis (CF), however the utility of LCI to identify subgroups of CF disease in the paediatric age group has never been explored. The aim of the study was to characterize phenotypes of children with CF using LCI as a marker of ventilation inhomogeneity and to investigate whether these phenotypes distinguished patients based on time to pulmonary exacerbation (PE). METHODS: Data were collected on patients with CF aged < 18 years old, attending the CF Center of Milan during outpatient follow-up visits between October 2014 and September 2019. Cluster analysis using agglomerative nesting hierarchical method was performed to generate distinct phenotypes. Time-to-recurrent event analysis investigated association of phenotypes with PE. RESULTS: We collected 313 multiple breath washout tests on 125 children aged 5.5-16.8 years. Cluster analysis identified two divergent phenotypes in children and adolescents of same age, presenting with almost normal FEV1 but with substantial difference in markers of ventilation inhomogeneity (mean LCI difference of 3.4, 95% Confidence Interval [CI] 2.6-4.2). A less severe phenotype was associated with a lower risk of PE relapse (Hazard Ratio 0.45, 95% CI 0.34-0.62). CONCLUSIONS: LCI is useful in clinical practice to characterize distinct phenotypes of children and adolescents with mild/normal FEV1. A less severe phenotype translates into a lower risk of PE relapse.

Short-term effects of positive expiratory pressure mask on ventilation inhomogeneity in children with cystic fibrosis: A randomized, sham-controlled crossover study.

BACKGROUND: Can physiotherapy with a positive expiratory pressure (PEP) mask improve peripheral ventilation inhomogeneity, a typical feature of children with cystic fibrosis (cwCF)? To answer this question, we used the nitrogen multiple-breath washout (N2MBW) test to measure diffusion-convection-dependent inhomogeneity arising within the intracinar compartment (Sacin*VT). METHODS: For this randomized, sham-controlled crossover trial, two N2MBW tests were performed near the hospital discharge date: one before and the other after PEP mask therapy (1 min of breathing through a flow-dependent PEP device attached to a face mask, followed by three huffs and one cough repeated 10 times) by either a standard (10-15 cmH20) or a sham (<5 cmH20) procedure on two consecutive mornings. Deception entailed misinforming the subjects about the nature of the study; also the N2MBW operators were blinded to treatment allocation. Study outcomes were assessed with mixed-effect models. RESULTS: The study sample was 19 cwCF (ten girls), aged 11.4 (2.7) years. The adjusted Sacin*VT mean difference between the standard and the sham procedure was -0.015 (90% confidence interval [CI]: -∞ to 0.025) L-1. There was no statistically significant difference in Scond*VT and lung clearance index between the two procedures: -0.005 (95% CI: -0.019 to 0.01) L-1 and 0.49 (95% CI: -0.05 to 1.03) turnovers, respectively. CONCLUSION: Our findings do not support evidence for an immediate effect of PEP mask physiotherapy on Sacin*VT with pressure range 10-15 cmH20. Measurement with the N2MBW and the crossover design were found to be time-consuming and unsuitable for a short-term study of airway clearance techniques.

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.

Using electrical impedance tomography to characterize lung impairment of children with primary ciliary dyskinesia: A pilot cross-sectional study.

BACKGROUND: In children with primary ciliary dyskinesia (PCD), measures more sensitive than spirometry are needed to characterize underlying pulmonary impairment. Electrical impedance tomography (EIT) is a promising noninvasive method for monitoring the distribution of lung ventilation, and it does not require patient collaboration. We aimed to provide an assessment of the feasibility and clinical usefulness of EIT in characterizing lung impairment in children with PCD, compared to spirometry and multiple breath nitrogen washout (MBWN2 ) test. METHODS: Children and adolescents with PCD underwent MBWN2 test as first respiratory assessment, followed by EIT monitoring and spirometry during outpatient follow-up. RESULTS: We included 12 out of 16 individuals regularly followed at our clinic. A total of 41.7% (5/12) showed abnormal forced expiratory volume in 1 s (FEV1 ), whereas 11/12 (91.7%) had abnormal ventilation inhomogeneity measured with MBWN2 test. Using EIT, the global inhomogeneity (GITOT ) index showed moderate to strong correlation with FEV1 (ρ = -0.55, 95% confidence interval [CI]: -0.87 to 0.02) and ranged from 37 to 44, with the highest inhomogeneity detected in the dorsal right quadrant. GITOT was moderately correlated with RV/TLC %predicted (ρ = 0.38, 95% CI: -0.17 to 0.74), while we detected a weak correlation between GITOT and lung clearance index (ρ = 0.29, 95% CI: -0.45 to 0.82). CONCLUSION: EIT appears promising as a noninvasive technique to characterize ventilation distribution in children with PCD, thus providing a complementary assessment to static and dynamic lung function measures of PCD disease.

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.

Prevalence and factors associated with urinary incontinence in females with cystic fibrosis: An Italian single-center cross-sectional analysis.

BACKGROUND: Individuals with cystic fibrosis (CF) are deemed to have a higher risk of developing urinary incontinence (UI), likely due to repeated increasing pressure on the pelvic floor. We aimed to determine the prevalence of female UI in a large CF referral center, and to assess the association between UI and severity of CF disease. METHODS: We consecutively recruited female patients regularly attending our CF center, aged ≥6 years and with a confirmed diagnosis of CF. Prevalence, severity, and impact of UI were assessed by administering two validated questionnaires. Relationship between variables was evaluated by means of multiple correspondence analysis, whereas a logistic model was fitted to capture the statistical association between UI and independent variables. RESULTS: UI was present in 51/153 (33%, 95% confidence interval [CI]: 26%-41%) females. Among children and adolescents, the prevalence was 12/82 (15%, 95% CI: 8%-25%) whereas among adults was 39/71 (55%, 95% CI: 43%-67%). The only explanatory variable associated with UI was age, with children presenting the lowest risk (odds ratio, 0.32; 95% CI: 0.05-0.93). Females presenting low or high nutritional status show higher profile risk of having UI. CONCLUSIONS: Stress UI is a common complication in females with CF since childhood. Although it frequently occurs in older patients with a more severe phenotype, much attention should be paid to adults and to their nutritional status.

Multiple Breath Washout for Early Assessment of Pulmonary Complications in Patients With Primary Antibody Deficiencies: An Observational Study in Pediatric Age.

Background: In primary antibody deficiencies (PADs), pulmonary complications are the main cause of morbidity, despite immunoglobulin substitutive therapy, antibiotic treatment of exacerbations, and respiratory physiotherapy. Current Italian recommendations for surveillance of PADs respiratory complications include an annual assessment of spirometry and execution of chest high-resolution computed tomography (HRCT) every 4 years. Objective: This study aimed to evaluate the effectiveness of the lung clearance index (LCI) as an early marker of lung damage in patients with PADs. LCI is measured by multiple breath washout (MBW), a non-invasive and highly specific test widely used in patients with cystic fibrosis (CF). Methods: Pediatric patients with PADs (n = 17, 10 male, 7 female, and age range 5-15 years) underwent baseline assessment of lung involvement with chest HRCT, spirometry, and multiple breath nitrogen washout. Among them, 13 patients were followed up to repeat HRCT after 4 years, while performing pulmonary function tests annually. Their baseline and follow-up LCI and forced expiratory volume at 1 s (FEV1) values were compared, taking HRCT as the gold standard, using logistic regression analysis. Results: Lung clearance index [odds ratio (OR) 2.3 (confidence interval (CI) 0.1-52) at baseline, OR 3.9 (CI 0.2-191) at follow-up] has a stronger discriminating power between altered and normal HRCT rather than FEV1 [OR 0.6 (CI 0.2-2) at baseline, OR 1.6 (CI 0.1-13.6) at follow-up]. Conclusion: Within the context of a limited sample size, LCI seems to be more predictive of HRCT alterations than FEV1 and more sensitive than HRCT in detecting non-uniform ventilation in the absence of bronchiectasis. A study of a larger cohort of pediatric patients followed longitudinally in adulthood is needed to challenge these findings.

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

BACKGROUND: Lung clearance index (LCI2.5 ) 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. Sacin and LCI2.5 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 LCI2.5 . CONCLUSION: Exercise capacity and airflow obstruction are associated in this Italian CF cohort. Considering the greater discriminatory power of LCI2.5 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.

Expiratory muscle strength and functional exercise tolerance in adults with cystic fibrosis: a cross-sectional study.

OBJECTIVE: A 6-minute walk work (6MWW), that is the product of distance walked at the 6-minute walk test (6MWT) multiplied by body weight, has been suggested as an appropriate variable for estimating functional capacity. Under the hypothesis that 6MWW strongly correlates with expiratory muscle strength (PE max), as found in Chronic Obstructive Pulmonary Disease (COPD), the aim of the study was to determine the degree of this correlation in adults with cystic fibrosis. METHODS: A cross-sectional study was carried out at the Regional Referral Centre for Cystic Fibrosis, where patients with cystic fibrosis attending their regular follow-up, aged 18 years or older with mild-to-normal lung disease, were asked to participate. Dietitians determined nutritional status before subjects performed spirometry and static measurement of respiratory muscles. The 6MWT was performed as the last study procedure. Spearman correlation test was used to correlate PE max with 6MWW and other study variables. RESULTS: Twenty-five cystic fibrosis subjects aged 18-30 years and with FEV1 values ranging from 42.4% to 123.4% predicted completed the study. PE max strongly correlated with 6MWW (rho .72, p = .0001) whereas it did not correlate with other study variables, including distance at the 6MWT. Distance walked multiplied by body weight (p = .0019) and body mass index (p = .0238) were significantly lower in those with PE max below the lower limits of normal. CONCLUSION: Increased functional exercise tolerance is related to higher static expiratory pressure in patients with mild-to-normal cystic fibrosis lung disease. Difference in exercise performance might reflect a possible difference in body composition that needs to be further investigated.

Aerosol delivery practice in Italian Cystic Fibrosis centres: a national survey.

BACKGROUND: Physiotherapists (PTs) are ideally positioned to assist patients and families with inhalation therapies through monitoring, communication and education about available therapies and their proper use; indeed aerosoltherapy management is listed as part of Italian PTs' core competence and in the core syllabus for post-graduate training in respiratory physiotherapy. The aim of this study was to outline the involvement of Italian PTs working in Cystic Fibrosis (CF) centres in the aerosol delivery practice. METHODS: Physiotherapist coordinators (n = 29) of all Italian CF centres were invited to participate in a cross-sectional survey and a semi-structured questionnaire was developed and sent by e-mail. RESULTS: A response rate of 69 % was achieved. The majority of participants were woman and the overall mean professional experience was twenty years. Italian PTs are involved in the aerosol delivery practice, managing education, drug-device combination, dilution and mixing of drugs. CONCLUSIONS: Physiotherapists play a key role in the care of Italian CF patients; nevertheless the Italian Group of Physiotherapists might plan interventions to harmonize the aerosol delivery practice in Italian CF centres and to sustain continuing education.