| Abstract: | This study assessed the ability of functional magnetic stimulation (FMS) to activate the respiratory muscles in dogs. With the animal supine, FMS of the phrenic nerves using a high-speed magnetic stimulator was performed by placing a round magnetic coil (MC) at the carotid triangle. Following hyperventilation-induced apnea, changes in volume (ΔV) and airway pressure (ΔP) against an occluded airway were determined. FMS of the phrenic nerves produced substantial inspired function (ΔV = 373 ± 20.5 mL and ΔP = −20 ± 2.0 cm H2O). After bilateral phrenectomies, maximal inspired ΔV (219 ± 12.2 mL) and ΔP (−10 ± 1.0 cm H2O) were produced when the MC was placed near the C6–C7 spinous processes, while maximal expired ΔV (−199 ± 22.5 mL) and ΔP (11 ± 2.3 cm H2O) were produced following stimulation near the T9–T10 spinous processes. We conclude: (1) FMS of either the phrenic or upper intercostal nerves results in inspired volume production; (2) FMS of the lower intercostal nerves generates expired volume production; and (3) FMS of the respiratory muscles may be a useful noninvasive tool for artificial ventilation and assisted cough in patients with spinal cord injuries or other neurological disorders. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:1048–1057, 1998. |
