RESUMO
INTRODUCTION: The aim of this study was to investigate the immediate effect of coughing episodes and diaphragmatic breathing exercise (DBE) on respiratory mechanics of children/adolescents with cystic fibrosis (CF). METHODS: It is a cross-sectional analytical study that occurred in a reference center for children with CF. Forty-five children/adolescents with CF (60% male; mean age 10.22 ± 2.84 years old; mean forced expiratory volume in 1 second 73.74 ± 21.38% predicted) were divided into 3 groups according to the R5 parameter response to the DBE: G1 (increased R5), G2 (no change R5), and G3 (decreased R5). The children/adolescents performed 5 successive coughs and 10 DBE. The main outcome measures were the impulse oscillometry system (IOS) parameters evaluated before, during, and after the interventions. RESULTS: In the total sample, the IOS parameters (Z5, R5, and R20) were worse after coughing, and they did not change after the DBE. In the G1, the parameters were progressively worsening during the interventions. In the G2, they worsened after coughing and after the DBE. In the G3, they worsened after coughing; however, after the DBE, the IOS parameters have improved and returned close to the baseline. CONCLUSIONS: The children/adolescents with CF airway resistance got worse after coughing episodes, and 10 DBE repetitions did not affect the respiratory mechanics in most of the sample. Meanwhile, in the group with older children, the DBE worsened the respiratory mechanics, yet in the younger group it improved.