Efeitos agudos de diferentes posicionamentos sobre o pico de fluxo de tosse e ativação eletromiográfica dos músculos respiratórios em indivíduos com distrofia muscular de Duchenne

Abstract

Introduction: Duchenne Muscular Dystrophy (DMD) is the most common form of myopathy affecting children of the male gender. As the disease progresses, respiratory muscle involvement leads to muscle weakness and reduced lung and chest wall expansion, with retention of secretions, due to the inability to generate an effective cough. Several factors determine the effectiveness of coughing. Since posture acts on peak cough flow (PCF) and respiratory muscle activity in DMD is not yet established. Objective: To evaluate and compare the acute effects of different postures on PCF variations and electromyographic activation of respiratory muscles in subjects with DMD versus healthy paired subjects. Methods: PCF, tidal volume (VT) of the rib cage compartments (pulmonary rib cage and the abdominal rib cage) and abdomen (AB) were evaluated through Optoelectronic Plethysmography and respiratory muscle activation: sternocleidomastoid (SCM) scalene (ESC), abdominal rectus (RA) and external oblique (EO) through surface electromyography (EMGs). The evaluation was performed in three positions: supine, supine with trunk elevated at 45o (45o ) and supine with trunk elevated at 80o (80o ) in subjects with DMD, Duchenne group (DG), paired with healthy subjects, control group (CG). Results: 35 individuals with DMD were assessed (23 excluded), of whom 12 subjects composed the DG being paired with 12 healthy subjects, who composed the GC. The GD subjects had lower CPF values in comparison to the CG, in addition, the DG presented lower CPF (p <0.05) in supine versus 80o . The electromyographic activity during the inspiratory and expiratory phases of coughing were lower in the DG versus CG in all evaluated muscles (p <0.05). Our results demonstrate that in DMD, the CPF cough is favored the more erect the trunk, while the electromyographic activity is not influenced by the change in positioning, being reduced when compared to the healthy ones.