Pulmonary function testing in spinal cord injury: effects of abdominal muscle stimulation

The purpose of this study was to assess the effects of applying transcutaneous electrical stimulation to paralyzed abdominal muscles during pulmonary function testing (PFT) of individuals with spinal cord injury (SCI). Ten male subjects with anatomical level of SCI between C5-T7 were studied. Subjects performed PFTs with and without electrical stimulation delivered to the abdominal muscles. Subjects with the lowest percentage of predicted expiratory volumes and flows demonstrated the greatest improvement when electrical stimulation was delivered during forced expiration. The overall increases seen in percent of predicted for the study sample were 23 percent for forced vital capacity (FVC), 16 percent for forced expiratory flow in 1 s (FEV1), and 22 percent for peak expiratory flow rate (PEF). Contractions of paralyzed expiratory muscles in response to electrical stimulation during the performance of PFT maneuvers can significantly improve FVC, FEV1, and PEF in some individuals with SCI.