Association of the three-minute step test with the occurrence of pulmonary exacerbations in children with cystic fibrosis: a cross-sectional study.

BACKGROUND: Cystic fibrosis (CF) patients experience pulmonary exacerbations and the three-minute step test (3-min step test) may be a simple and easy-to-perform functional test to help identify such episodes. The present study aimed to evaluate the association of the 3-min step test with the occurrence of pulmonary exacerbations in children with CF. METHODS: Cross-sectional study of CF patients aged 6 years and older. Pulmonary exacerbations were assessed using both the Fuchs criteria and the Kanga Score. The 3-min step test was performed using a 15 cm-high step and heart rate (HR), oxygen saturation (SpO2), and dyspnea were measured before and after the test. Correlations between the test and the scores, as well as comparisons between patients experiencing or not an exacerbation, were performed. RESULTS: Sixty-two patients (11.1±4.3 years) were included. Both the Fuchs criteria and the Kanga score correlated significantly with age, forced expiratory volume in the first second (FEV1), final SpO2, and 1-min recovery SpO2. A fall greater than 4% in the final SpO2 was significantly associated with the presence of a pulmonary exacerbation, considering both Fuchs and Kanga criteria. Age, resting HR, and HR after 1-min recovery were significantly higher, while FEV1, SpO2 at rest, final SpO2, and SpO2 after 1-min recovery were significantly lower in patients classified as exacerbated. CONCLUSIONS: Physiological responses to the 3-min step test are associated with the occurrence of pulmonary exacerbation in children with CF. Desaturation at the end of the test or during 1-min recovery may be the best variable to monitor.

Ventilatory Threshold and Risk of Pulmonary Exacerbations in Cystic Fibrosis.

BACKGROUND: Whereas pulmonary exacerbations and aerobic fitness play a key role in the prognosis of cystic fibrosis (CF), the use of ventilatory threshold data as markers of exacerbation risk has been scarcely addressed. This study sought to examine the association between aerobic fitness, assessed through ventilatory threshold variables recorded during cardiopulmonary exercise testing (CPET), and the risk of exacerbations in individuals with CF. METHODS: Participants of this retrospective cohort study were subjects from 6 y of age. Over a 4-y period, the following data were recorded: lung function indicators, CPET variables, time to first exacerbation and antibiotic use, along with demographic, clinical, and anthropometric data. RESULTS: The mean age of 20 subjects included was 16 ± 5.4 y. Univariate regression analysis revealed that lung function (FEV1: Cox hazard ratio [HR] 0.97, P = .03; and forced expiratory flow between 25-75% of vital capacity [FEF25-75]: Cox HR 0.98, P = .036) and aerobic fitness (oxygen consumption [V̇O2 ] at ventilatory threshold: Cox HR 0.94, P = .01; and ventilatory equivalent for carbon dioxide [V̇E/V̇CO2 ] at ventilatory threshold: Cox HR 1.13, P = .049) were associated with exacerbation risk, whereas in the multivariate model, only V̇O2 at the ventilatory threshold (%max) (Cox HR 0.92, P = .01) had a significant impact on this risk. Consistently, individuals experiencing exacerbation had significantly lower V̇O2 values (%max) at the ventilatory threshold (P = .050) and higher ventilatory equivalent for oxygen consumption (V̇E/V̇O2 ) (P = .040) and V̇E/V̇O2 (P = .037) values at the ventilatory threshold. Time to exacerbation was significantly correlated with V̇O2 at the ventilatory threshold (r = 0.50, P = .02), V̇E/V̇O2 (r = -0.48, P = .02), and V̇E/V̇CO2 (r = -0.50, P = .02). CONCLUSIONS: Our results suggest an association between CPET variables at the ventilatory threshold and exacerbations. Percentage V̇O2 at the ventilatory threshold could serve as a complementary variable to monitor exacerbations in people with CF.

The Association of Field Test Outcomes with Peak Oxygen Uptake in Patients with Cystic Fibrosis: A Systematic Review.

The purpose of the study was to evaluate the association of field test outcomes with peak oxygen uptake (VO2peak) in patients with cystic fibrosis (CF) and to describe the main prediction equations available. Data searches were performed in five databases (Pubmed, Embase, LILACs, Scopus and Web of Science) and also in the reference lists of articles included. The following inclusion criteria were used: studies including individuals with CF, presenting both a field test and a cardiopulmonary exercise testing (CPET), and describing a predictive equation or coefficient of correlation/determination. Case studies, abstracts, letters of reply, editorials and duplicate publications were excluded. The methodological quality analysis was performed using the JBI Critical Appraisal Checklist for Analytical Cross-Sectional Studies scale. Protocol registration number: CRD42020148363. Ten studies were eligible. Five equations were found to predict VO2peak. Equations derived from the shuttle tests (ST) showed strong correlations with VO2peak (r = 0.79 to 0.95). The six-minute walk test (6MWT) showed moderate associations with VO2peak in participants with moderate disease severity (r = 0.53 to 0.65). Furthermore, patients with lower maximum heart rate on the three-minute step test tended to have a higher percent predicted VO2peak (r = -0.40), and the one-minute sit-to-stand test demonstrated moderate correlations between VO2peak and the number of repetitions (r = 0.52 to 0.66). In conclusion, field test outcomes correlate with oxygen consumption assessed through CPET, although only the ST seems to be valid as a predictor of VO2peak in patients with CF.

Comparison of physical fitness between healthy and mild-to-moderate asthmatic children with exercise symptoms: A cross-sectional study.

OBJECTIVE: Asthma is a chronic disease that may affect physical fitness, although its primary effects on exercise capacity, muscle strength, functionality and lifestyle, in children and adolescents, are still poorly understood. This study aimed to evaluate the differences in cardiorespiratory fitness, muscle strength, lifestyle, lung function, and functionality between asthmatics with exercise symptoms and healthy children. In addition, we have analyzed the association between clinical history and the presence of asthma. STUDY DESIGN: Cross-sectional study including 71 patients with a diagnosis of asthma and 71 healthy children and adolescents (7-17 years of age). Anthropometric data, clinical history, disease control, lifestyle (KIDMED and physical activity questionnaires), lung function (spirometry), exercise-induced bronchoconstriction test, aerobic fitness (cardiopulmonary exercise test), muscle strength and functionality (timed up and go; timed up and down stairs) were evaluated. RESULTS: Seventy-one patients with asthma (mean age 11.5 ± 2.7) and 71 healthy subjects (mean age 10.7 ± 2.5) were included. All asthmatic children had mild to moderate and stable asthma. EIB occurred in 56.3% of asthmatic children. Lung function was significantly (p < .05) lower in the asthmatic group when compared to healthy peers, as well as the cardiorespiratory fitness, muscle strength, lifestyle and functionality. Moreover, asthmatic children were more likely to have atopic dermatitis, allergic reactions, food allergies, and a family history of asthma when compared to healthy children. CONCLUSIONS: Children with mild-to-moderate asthma presenting exercise symptoms show a reduction in cardiorespiratory fitness, muscle strength, lung function, functionality, and lifestyle when compared to healthy peers. The study provides data for pediatricians to support exercise practice aiming to improve prognosis and quality of life in asthmatic children.

Prediction of peak oxygen uptake using the modified shuttle test in children and adolescents with cystic fibrosis.

BACKGROUND: Several tests may be used to assess exercise intolerance in cystic fibrosis (CF), including the gold standard cardiopulmonary exercise test (CPET) and the Modified Shuttle Test (MST). OBJECTIVE: To evaluate the use of the MST as a predictor of peak oxygen uptake (VO2 peak) and to compare VO2 peak and maximal heart rate (HRmax) obtained in both tests. METHODS: Cross-sectional study including individuals with CF aged between 6 and 20 years old. Participants who were unable to perform the tests and/or presented signs of pulmonary exacerbation were excluded. Demographic, anthropometric, clinical and spirometric values ​​were collected. CPET and the MST were performed in two consecutive outpatient visits. HRmax, peripheral oxygen saturation, dyspnea, and VO2 peak measured and estimated were compared. RESULTS: Twenty-four patients, mean age 15.7 ± 4.2 years and FEV1 (% predicted) 76.4 ± 23.8, were included. Mean values ​​of HRmax (bpm) and HRmax in percent of predicted (HRmax%) were lower (P = 0.01) in the MST (171.6 ± 14.5 and 87.1 ± 7.5) compared to CPET (180.9 ± 10.0 and 91.9 ± 5.4). However, there was no significant differences between tests in the variation (delta) for HRmax and HRmax% (P = 0.17). A strong correlation (r = 0.79; P < 0.0001) was found between distance achieved (MST) and VO2 peak (CPET). The regression model to estimate VO2 peak resulted in the following equation: VO2 (mL · kg-1 · min-1 ) = 20.301 + 0.019 × MST distance (meters). There was no difference (P = 0.50) between VO2 peak measured (CPET) and estimated by the equation. CONCLUSION: The MST may be an alternative method to evaluate exercise capacity and to predict VO2 peak in children and adolescents with CF.

Six-Minute Walk Test Results Predict Risk of Hospitalization for Youths with Cystic Fibrosis: A 5-Year Follow-Up Study.

OBJECTIVE: To evaluate the association of 6-minute walk test (6MWT) and other variables (anthropometry, chronic Pseudomonas aeroginosa colonization, pulmonary function, and respiratory muscle strength) with the risk of hospitalization for pulmonary exacerbation in children and adolescents with cystic fibrosis (CF). STUDY DESIGN: Cohort study that included patients with CF aged 6-18 years. All participants underwent spirometry, manovacuometry, and 6MWT during the 5-year follow-up. Anthropometric and clinical data were collected and the time to first hospitalization, total days of hospitalization, and antibiotic use during follow-up was recorded. RESULTS: A total of 26 patients with CF, mean age 10.2 ± 2.8 years, were included. The group had mild impairment of lung function with a significant decline in forced expiratory volume in 1 second (P = .019) over the 5 years. Respiratory muscle strength and 6MWT proved to be preserved, although maximum inspiratory pressure increased (P < .001) and maximum expiratory pressure and 6-minute walk distance (6MWD) remained stable. There were inverse associations of 6MWD in meters (r = -0.813, P < .001) and z score (r = -0.417, P = .015) with total days of hospitalization. Moreover, there was a reduction in the risk of a first hospitalization (Cox HR 0.32; P = .037) in patients with a greater 6MWD. CONCLUSIONS: We found an association between the 6MWT and the risk of hospitalization in children and adolescents with CF. Furthermore, functional capacity apparently does not follow the expected decline in pulmonary function over time, whereas inspiratory muscle strength increases with disease progression.

Inspiratory Muscle Strength and Endurance in Children and Adolescents with Cystic Fibrosis.

BACKGROUND: Pulmonary changes that occur in cystic fibrosis may influence inspiratory muscle strength and endurance. We evaluated inspiratory muscle strength and endurance in children and adolescents with cystic fibrosis in comparison with healthy subjects. METHODS: This is a cross-sectional observational study with subjects with cystic fibrosis and paired healthy individuals, age 6-18 y. Spirometry, impulse oscillometry, plethysmography, manovacuometry, and a protocol of inspiratory muscle endurance were performed. RESULTS: Subjects with cystic fibrosis (n = 34) had higher maximum percent-of-predicted inspiratory pressure (PImax) than healthy (n = 68) subjects (118.5 ± 25.8% vs 105.8 ± 18.0%) and no significant difference in endurance (60.9 ± 13.3% vs 65.3 ± 12.3%). When restricting the analysis to subjects without Pseudomonas aeruginosa colonization and with FEV1 > 80%, PImax values were significantly higher, and inspiratory muscle endurance was lower, in comparison with the control group. PImax correlated significantly with FVC (r = 0.44, P = .02) and FEV1 (r = 0.41, P = .02), whereas endurance correlated better with total airway resistance (r = 0.35, P = .045) and with central airway resistance (r = 0.48, P = .004). CONCLUSIONS: Children and adolescents with cystic fibrosis with no colonization by P. aeruginosa and normal lung function present increased inspiratory muscle strength and decreased endurance compared with healthy individuals, indicating that changes in the respiratory muscle function seem to be distinctly associated with pulmonary involvement. Strength was related to pulmonary function parameters, whereas endurance was associated with airway resistance.