Forced expiration technique: impact on the respiratory mechanics parameters of children and adolescents with cystic fibrosis.

Objective: Determine the immediate effect of forced expiration technique (FET) on the respiratory mechanics of children and adolescents with cystic fibrosis (CF). As a secondary objective, the effect of cough induced by FET was evaluated by comparing respiratory mechanics and lung function between those who coughed and those who did not during the FET.

Methods: A before-after clinical trial was conducted with children and adolescents with CF aged six to 15 years. Respiratory mechanics parameters were assessed using the impulse oscillometry system (IOS) in three stages: basal IOS, post-huff IOS, and final post-diaphragmatic breathing exercises (DBE) IOS. For the intervention, FET was requested with five low-volume followed by three high-volume huffs, and finally ten DBE repetitions. Coughing occurred randomly and was not previously requested. To investigate whether FET-induced coughing alters oscillometric parameters, the participants were divided into two groups: those who presented with cough (CG) during the protocol and those who did not (NCG).

Results: Forty-three children and adolescents with CF participated in the study (51.2% female), with an average age of 10.44±2.64 years, where forced expiratory value - FEV1=78.51±23.28%, and body mass index - BMI=17.18±2.24 kg/m2. The huffing sequence increased all oscillometric parameters, while DBE repetitions led to an increase in these parameters, without a complete return to baseline values. In terms of coughing, there was no significant difference between the NCG and CG in any of the parameters studied.

Conclusions: It was observed that, during the FET, diaphragmatic breathing exercises can attenuate the effort exerted by the forced expiratory maneuver on the airways.