Activation of the expiratory muscles via lower thoracic high frequency spinal cord stimulation in awake animals

• Published in: Respiratory physiology & neurobiology 2020-05, Vol.276, p.103360-103360, Article 103360
• Main Authors: DiMarco, Anthony F., Kowalski, Krzysztof E.
• Format: Article
• Language: English
• Subjects: Cough; Expiratory muscles; Rehabilitation; Spinal cord stimulation
• ISSN: 1569-9048; 1878-1519
• DOI: 10.1016/j.resp.2019.103360

•An experimental model of electrical activation of the abdominal muscles was evaluated in awakeanimals.•The effects of dorsal epidural spinal cord stimulation on expiratory muscle force generation, expansion of the abdominal wall and EMG activity were examined.•High frequency spinal cord stimulation to activate the expiratory muscles results in large airway pressures characteristic of a normal cough.•High frequency spinal cord stimulation was not associated with animal discomfort as determined by lack of changes in heart rate or vocalization.•This method may be a useful method to restore an effective cough mechanism in individuals with intact sensation. Lower thoracic spinal cord stimulation is an effective method of restoring an effective cough in participants with complete spinal cord injury. The high voltage requirements however significantly limits this application in subjects with intact lower chest wall sensation. In anesthetized animals, we have shown that the expiratory muscles can also be effectively activated with low stimulus currents (1 mA) but with high stimulus frequencies (HF-SCS -500 Hz). In 3 intact, awake pigs the responses to HF-SCS, were evaluated. HF-SCS was associated with marked expansion of the abdominal wall and external oblique EMG activity without any associated changes in heart rate or vocalization. During a terminal procedure under general anesthesia, responses to HF-SCS were re-assessed. Abdominal movement and EMG were similar to that observed in the awake state. HF-SCS (1.5 mA) resulted in an airway pressure of 65 ± 2cmH2O. Our results indicate that lower thoracic HF-SCS may be a useful method to restore an effective cough in patients with intact chest wall sensation.