The purpose of the present study is to assess the utility of abdominal muscle stimulation to
provide large positive airway pressures and expiratory airflow thus simulating cough.
Restoration of cough in spinal cord injured patients may reduce the incidence of respiratory
complications such as atelectasis, respiratory tract infections and respiratory failure.
Cough is a complex defensive respiratory reflex mechanism necessary for the clearance of
respiratory secretions and foreign materials. In patients with chronic bronchitis, previous
investigations have found that the cough mechanism is the most effective measure to enhance
mucous clearance from the lung.
Patients with cervical and thoracic spinal cord injuries have suffered a loss of the major
portion of their expiratory muscles. Consequently, they are unable to generate significant
positive intrathoracic airway pressures or airflow and have a markedly increased risk of
developing pulmonary infections. Mechanical methods have been developed to enhance cough
production. However, these have resulted in only marginal increases in airway pressure.
Preliminary studies in our laboratory in animal experiments and those of others in humans
have suggested that the abdominal muscles can be stimulated directly by surface electrodes.
The purpose of the present study, therefore, is to assess the utility of abdominal muscle
stimulation in quadriplegics and paraplegics to simulate cough. A range of stimulus
parameters and electrode locations will be assessed to determine optimal stimulus paradigms.
Airway pressure and expiratory airflow will be used as indices of cough effectiveness. If
successful, abdominal muscle stimulation may be a useful tool to restore cough and hopefully
reduce the incidence of respiratory complications such as atelectasis and infection in
spinal cord injured patients.
- Patients with cervical or thoracic spinal cord injury
- Significant cardiovascular disease
- Active lung disease
- Pacemaker or other metallic implant
- Legally incompetent