Abdominal Muscle Training Can Enhance Cough After Spinal Cord Injury

McBain, Rachel A.
Boswell-Ruys, Claire L. PhD
Lee, Bonsan B. PhD
Gandevia, Simon C. DSc
Butler, Jane E. PhD

¹Neuroscience Research Australia, Randwick, New South Wales, Australia
²University of New South Wales, Randwick Campus, Randwick, New South Wales, Australia
³Prince of Wales Hospital, Randwick, Australia

Jane E. Butler, Neuroscience Research Australia, Barker Street, Randwick, New South Wales 2031, Australia. Email: e-mail; [email protected]

Neurorehabilitation and Neural Repair 27(9):p 834-843, November-December 2013. | DOI: 10.1177/1545968313496324

Background.

Respiratory complications in people with high-level spinal cord injury (SCI) are a major cause of morbidity and mortality, particularly because of a reduced ability to cough as a result of abdominal muscle paralysis.

Objective.

We investigated the effect of cough training combined with functional electrical stimulation (FES) over the abdominal muscles for 6 weeks to observe whether training could improve cough strength.

Methods.

Fifteen SCI subjects (C4-T5) trained for 6 weeks, 5 days per week (5 sets of 10 coughs per day) in a randomized crossover design study. Subjects coughed voluntarily at the same time as a train of electrical stimulation was delivered over the abdominal muscles via posterolaterally positioned electrodes (50 Hz, 3 seconds). Measurements were made of esophageal (P_es) and gastric (P_ga) expiratory pressures and the peak expiratory flow (PEF_cough) produced at the 3 time points of before, during, and after the training.

Results.

During voluntary coughs, FES cough stimulation improved P_ga, P_es, and PEF_cough acutely, 20-fold, 4-fold, and 50%, respectively. Six weeks of cough training significantly increased P_ga (37.1 ± 2.0 to 46.5 ± 2.9 cm H₂O), P_es (35.4 ± 2.7 to 48.1 ± 2.9 cm H₂O), and PEF_cough (3.1 ± 0.1 to 3.6 ± 0.1 L/s). Cough training also improved pressures and flow during voluntary unstimulated coughs.

Conclusions.

FES of abdominal muscles acutely increases mechanical output in coughing in high-level SCI subjects. Six weeks of cough training further increases gastric and esophageal cough pressures and expiratory cough flow during stimulated cough maneuvers.