Complete Restoration of Respiratory Muscle Function in Three Subjects With Spinal Cord Injury Pilot Interventional Clinical Trial

Objectives The aim of this study was to assess the safety and efficacy of complete restoration of respiratory muscle function in subjects with spinal cord injury. Methods This was an interventional study investigating three subjects maintained on a diaphragm pacing system who were implanted with the spinal cord stimulation system to restore cough. Peak expiratory airflow and airway pressure generation were the primary physiologic outcome measures; an assessment of the degree of difficulty in raising secretions was the primary clinical outcome measure. Results Mean peak expiratory airflow and airway pressure generation during spontaneous efforts were 1.7 +/- 0.2 L/s and 31 +/- 7 cmH(2)O, respectively. When spinal cord stimulation was applied after pacing volume associated with the subject's maximum inspiratory effort and synchronized with the subject's maximum expiratory effort, peak expiratory airflow and airway pressure generation were 9.0 +/- 1.9 L/s and 90 +/- 6 cmH(2)O, respectively (P < 0.05). Moreover, each subject experienced much greater ease in raising secretions and marked improvement in the ease in raising secretions compared with other methods. Conclusions Complete restoration of respiratory muscle function can be safely and effectively achieved in the same individuals with spinal cord injury. Spinal cord stimulation results in peak expiratory airflow and airway pressure generation characteristic of a normal cough, whereas diaphragm pacing was successful in maintaining patients off mechanical ventilation.