Six-minute walk test as a determinant of the functional capacity of children and adolescents with cystic fibrosis: A systematic review.

Cystic Fibrosis (CF) is a multisystem disorder. The involvement of the respiratory system is frequent and culminates in dyspnea and exercise intolerance. Functional capacity is an important diagnostic tool, because it reflects the cardiorespiratory status, quality of life and prognosis. This systematic review aims to assess the reproducibility and validity of the six minute walk test (6MWT) to reflect the functional capacity of children and adolescents with cystic fibrosis, and also the correlation between 6MWT and lung function. Searches for articles were performed in eight databases using MeSH/DeCS keywords. A total of 695 articles were found and, after verifying all eligibility criteria, six articles were included for analysis and scoring regarding the methodological quality according to the QUADAS scale (Quality Assessment of Diagnostic Accuracy Studies). All articles had good methodology (QUADAS between 9 and 11 points). The 6MWT is not correlated with lung function. There is a strong indication that the 6MWT is a reproducible test to assess the functional capacity of children and adolescents with CF. The validity assessment could not be reached because the studies included in this systematic review did not use adequate statistical tools to carry out such an evaluation.

Effects of noninvasive ventilation on treadmill 6-min walk distance and regional chest wall volumes in cystic fibrosis: randomized controlled trial.

BACKGROUND: Dyspnea and exercise intolerance are the symptoms that most affect the quality of life of children and adolescents with respiratory disorders resulting from cystic fibrosis (CF). OBJECTIVE: To evaluate the effect of noninvasive ventilation (NIV) on treadmill 6-min walk distance and regional chest wall volumes in cystic fibrosis patients. METHOD: Crossover clinical trial, randomized, controlled and open with 13 children and adolescents with CF, aged 7-16 years, with pulmonary impairment (NTC01987271). The patients performed a treadmill walking test (TWT) during 6 min, with and without NIV on a BiLEVEL mode, an interval of 24-48 h between tests. Before and after each test, patients were assessed by spirometry and optoelectronic plethysmography. RESULTS: Walking distance in TWT with NIV was significantly higher that without ventilatory support (mean ± sd: 0.41 ± 0.08 vs. 0.39 ± 0.85 km, p = 0.039). TWT with NIV increase forced expiratory volume on 1 s (FEV1; p = 0.036), tidal volume (Vt; p = 0.005), minute ventilation (MV; p = 0.013), pulmonary rib cage volume (Vrcp; p = 0.011), and decrease the abdominal volume (Vab; p = 0.013) after test. There was a significant reduction in oxygen saturation (p = 0.018) and permanent increase in respiratory rate after 5 min (p = 0.021) after the end test without NIV. CONCLUSION: During the walking test on the treadmill, the NIV change thoracoabdominal kinematics and lung function in order to optimized ventilation and tissue oxygenation, with improvement of walk distance. Consequently, NIV is an effective tool to increase functional capacity in children and adolescents with cystic fibrosis.