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

Abstract

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.

Keywords: Cystic fibrosis; Exercise test; Exercise tolerance; Noninvasive ventilation.