Respiratory responses to stimulation of abdominal and upper-thorax intercostal muscles using multiple Permaloc ® electrodes

Stimulation of abdominal and upper-thoracic mus- cles was studied with the long-term goal of improved respira- tory care for spinal cord injury (SCI) patients. A 12-channel stimulator and multiple surface and implanted Permaloc elec- trodes were evaluated in five anesthetized canines. Abdominal stimulation with 100 mA using four bilateral sets of surface electrodes placed on the midaxillary line at the 7th through 13th intercostal spaces and with a closed airway at a large lung vol- ume produced an expiratory tracheal pressure of 109 +/- 29 cm H2O (n = 2, mean +/- standard error of the mean). Similar high pressures were induced with implanted electrodes at the same locations. Upper-thoracic stimulation with 40 mA and four sets of implanted electrodes ventral to the axilla induced inspiratory pressures of 12 +/- 2 cm H2O (n = 5). Combined extradia- phragmatic pacing with an open airway produced a tidal volume of 440 +/- 45 mL (n = 4). The robust respiratory volumes and pressures suggest applications in SCI respiratory care.