Effects of Positioning on Cough Peak Flow and Muscular Electromyographic Activation in Duchenne Muscular Dystrophy

Abstract

BACKGROUND: Advanced stages of Duchenne muscular dystrophy (DMD) result in muscle weakness and the inability to generate an effective cough. Several factors influence the effectiveness of cough in patients with DMD. The aim of this study was to assess whether differences in positioning affect cough peak flow (CPF) and muscular electromyographic activation in subjects with DMD compared with paired healthy subjects. METHODS: Optoelectronic plethysmography and surface electromyography were used to assess chest wall volumes, chest wall inspiratory capacity, CPF, breathing pattern, and electromyographic activity of sternocleidomastoid, scalene, rectus abdominis, and external oblique muscles during inspiratory and expiratory cough phases in the supine position, supine position with headrest raised at 45 , and sitting with back support at 80 in 12 subjects with DMD and 12 healthy subjects. RESULTS: Subjects with DMD had lower CPF (P < .01) in comparison to control subjects in all positions; the DMD group also exhibited lower CPF (P 5 .045) in the supine position versus 80. Moreover, the relative volume contributions of the rib cage and abdominal compartments to tidal volume modified significantly with posture. The electromyographic activity during inspiratory and expiratory cough phases was lower in subjects with DMD compared to healthy subjects for all evaluated muscles (P < .05), but no significant differences were observed with posture change. CONCLUSIONS: In subjects with DMD, posture influenced CPF and the relative contribution of the rib cage and abdominal compartments to tidal volume. However, muscular electromyographic activation was not influenced by posture in subjects with DMD and healthy subjects.

Duchenne muscular dystrophy respiratory profiles from real world registry data

“…The association between loss of ambulation and a more rapid deterioration in FVC was recently reported in the Becker muscular dystrophy population 19 . Ambulation loss may contribute directly to pulmonary function decline via several mechanisms as the development of atelectasis, progression of scoliosis and secretion retention due to reduced peak cough flow may all reduce pulmonary compliance 20–22 . Even so, attributing ambulation loss as causative is likely an over simplification as the decline in pulmonary function is multifactorial and may be more dependent on the overall progression of muscular weakness 23 .…”

“…19 Ambulation loss may contribute directly to pulmonary function decline via several mechanisms as the development of atelectasis, progression of scoliosis and secretion retention due to reduced peak cough flow may all reduce pulmonary compliance. [20][21][22] Even so, attributing ambulation loss as causative is likely an over F I G U R E 1 FVC% relative to age (n = 323).…”

Thoracoabdominal asynchrony and paradoxical motion in Duchenne muscular dystrophy and healthy subjects during cough: A case control study

“…We previously showed in DMD subjects a significant lower muscular activation compared to controls during inspiratory and expiratory phases of coughing, 10 assessed by electromyographic activation of expiratory muscles (i.e., rectus abdominis, and external oblique). Also, Bernard et al 38 in DMD patients, suggesting paradoxical movement due to diaphragm co-contraction during maximal expiratory efforts.…”

“…Part of the results of this study was previously published. 10 The present study analyzed new variables and added two DMD patients.…”